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Kenji Hirata
Faculty of Medicine　Internal Medicine　Department of Radiology
Associate Professor
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Last Updated :2024/05/13

Researcher Profile and Settings

Affiliation

  • Faculty of Medicine　Internal Medicine　Department of Radiology

Job Title

  • Associate Professor

Degree

  • MD, PhD, FJCR, FANMB（2011/03 Hokkaido University）

URL

Research funding number

  • 30431365

J-Global ID

Research Interests

  • ChatGPT   natural language processing   radioisotope therapy   人工知能   radiology   computer aided diagnosis   脳腫瘍   ポジトロン断層撮影法   FMISO   低酸素   核医学(PET,SPECT)   画像診断学(含放射線診断学、核医学)   分子イメージング   

Research Areas

  • Life sciences / Tumor diagnostics and therapeutics
  • Life sciences / Radiology

Educational Organization

Academic & Professional Experience

  • 2020/04 - Today Hokkaido University Hospital Department of Nuclear Medicine Director
  • 2020/04 - Today 北海道大学大学院医学研究院 画像診断学教室 准教授
  • 2019/04 - 2020/03 北海道大学大学院医学研究院 画像診断学教室 助教
  • 2016/04 - 2019/03 北海道大学大学院医学研究院 核医学教室 助教
  • 2014/11 - 2016/03 Hokkaido University Department of Nuclear Medicine Special Academic Staff
  • 2012/11 - 2014/10 University of California, Los Angeles Department of Molecular and Medical Pharmacology Postdoc
  • 2012/04 - 2012/10 Hokkaido University Graduate School of Medicine
  • 2006/04 - 2012/03 北海道大学病院 核医学診療科 医員

Education

  • 2007/04 - 2011/03  北海道大学大学院医学研究科
  • 1996/04 - 2002/03  Hokkaido University  School of Medicine
  • 1993/04 - 1996/03  北海道岩見沢東高等学校

Association Memberships

  • 日本医療情報学会   日本メディカルAI学会   Japanese College of Radiology   日本核医学会   日本医学放射線学会   

Research Activities

Published Papers

  • Takeshi Nakaura, Rintaro Ito, Daiju Ueda, Taiki Nozaki, Yasutaka Fushimi, Yusuke Matsui, Masahiro Yanagawa, Akira Yamada, Takahiro Tsuboyama, Noriyuki Fujima, Fuminari Tatsugami, Kenji Hirata, Shohei Fujita, Koji Kamagata, Tomoyuki Fujioka, Mariko Kawamura, Shinji Naganawa
    Japanese journal of radiology 2024/03/29 
    The advent of Deep Learning (DL) has significantly propelled the field of diagnostic radiology forward by enhancing image analysis and interpretation. The introduction of the Transformer architecture, followed by the development of Large Language Models (LLMs), has further revolutionized this domain. LLMs now possess the potential to automate and refine the radiology workflow, extending from report generation to assistance in diagnostics and patient care. The integration of multimodal technology with LLMs could potentially leapfrog these applications to unprecedented levels.However, LLMs come with unresolved challenges such as information hallucinations and biases, which can affect clinical reliability. Despite these issues, the legislative and guideline frameworks have yet to catch up with technological advancements. Radiologists must acquire a thorough understanding of these technologies to leverage LLMs' potential to the fullest while maintaining medical safety and ethics. This review aims to aid in that endeavor.
  • Masahito Kawabori, Satoshi Kuroda, Hideo Shichinohe, Kaoru Kahata, Souichi Shiratori, Satoshi Ikeda, Taisuke Harada, Kenji Hirata, Khin Khin Tha, Masato Aragaki, Shunsuke Terasaka, Yoichi M Ito, Naoki Nishimoto, Shunsuke Ohnishi, Ichiro Yabe, Kohsuke Kudo, Kiyohiro Houkin, Miki Fujimura
    Med (New York, N.Y.) 2024/03/18 
    BACKGROUND: Ischemic stroke is one of the leading causes of death and neurological disability worldwide, and stem cell therapy is highly expected to reverse the sequelae. This phase 1/2, first-in-human study evaluated the safety, feasibility, and monitoring of an intracerebral-transplanted magnetic resonance imaging (MRI)-trackable autologous bone marrow stromal cell (HUNS001-01) for patients with subacute ischemic stroke. METHODS: The study included adults with severe disability due to ischemic stroke. HUNS001-01 cultured with human platelet lysates and labeled with superparamagnetic iron oxide was stereotactically transplanted into the peri-infarct area 47-64 days after ischemic stroke onset (dose: 2 or 5 × 107 cells). Neurological and radiographic evaluations were performed throughout 1 year after cell transplantation. The trial was registered at UMIN Clinical Trial Registry (number UMIN000026130). FINDINGS: All seven patients who met the inclusion criteria successfully achieved cell expansion, underwent intracerebral transplantation, and completed 1 year of follow-up. No product-related adverse events were observed. The median National Institutes of Health Stroke Scale and modified Rankin scale scores before transplantation were 13 and 4, which showed improvements of 1-8 and 0-2, respectively. Cell tracking proved that the engrafted cells migrated toward the infarction border area 1-6 months after transplantation, and the quantitative susceptibility mapping revealed that cell signals at the migrated area constantly increased throughout the follow-up period up to 34% of that of the initial transplanted site. CONCLUSIONS: Intracerebral transplantation of HUNS001-01 was safe and well tolerated. Cell tracking shed light on the therapeutic mechanisms of intracerebral transplantation. FUNDING: This work was supported by the Japan Agency for Medical Research and Development (AMED; JP17bk0104045 and JP20bk0104011).
  • Ayaka Maruo, Keiichi Magota, Yamato Munakata, Kenji Hirata, Chietsugu Katoh
    Annals of Nuclear Medicine 0914-7187 2024/03/13 [Refereed][Not invited]
  • Sho Kazui, Sakae Takenaka, Toshiyuki Nagai, Satonori Tsuneta, Kenji Hirata, Yoshiya Kato, Hirokazu Komoriyama, Yuta Kobayashi, Akinori Takahashi, Kiwamu Kamiya, Taro Temma, Takuma Sato, Atsushi Tada, Yutaro Yasui, Michikazu Nakai, Takahiro Sato, Ichizo Tsujino, Kohsuke Kudo, Satoshi Konno, Toshihisa Anzai
    JACC. Cardiovascular imaging 2024/03/11 [Refereed][Not invited]
  • Hironobu Hata, Satoshi Shimomura, Kenji Imamachi, Jun Sato, Takuya Asaka, Kenji Hirata, Kyousuke Funayama, Yoichi Mori, Masashi Matsuzaka, Toshikazu Nambu, Yoshimasa Kitagawa
    BMC oral health 24 (1) 305 - 305 2024/03/05 
    BACKGROUND: The long time required for bone uptake of radiopharmaceutical material after injection for bone scintigraphy is a burden for patients with poor health. Thus, to assess whether the uptake time could be reduced for single-photon emission computed tomography (SPECT) of the jawbone, this study evaluated differences in maximum standardized uptake values (SUVmax) within patients using SPECT imaging at 2 and 3 hours after radiopharmaceutical injection. METHODS: A total of 33 patients undergoing treatment or in post-treatment follow-up for medication-related osteonecrosis of the jaw, who visited our hospital between July 2020 and August 2021 and could receive SPECT twice on the same day, were enrolled in the study. Patients were injected with technetium-99 m hydroxymethylene diphosphonate (Tc-99 m HMDP) intravenously. The SUVmax for healthy parietal bones and jawbone lesions were calculated from the SPECT images using quantitative analysis software, and the SUVmax were compared between 2- and 3-hour uptake times. RESULTS: After exclusion, 30 patients were included in the study. In the 2-hour and 3-hour images, the median SUVmax of the parietal bones were 1.90 and 1.81, respectively, and those of the jawbone lesions were 9.25 and 9.39, respectively. The limits of agreement (LOA) ranged from - 0.33 to 0.25 in the parietal bones, and the %LOA ranged from - 9.8 to 17.3% in the jawbone lesions, showing high equivalence between the two uptake durations. The SUVmax showed no clinical differences between the 2- and 3-hour uptake durations for Tc-99 m HMDP SPECT of the jawbone. CONCLUSIONS: The results of this study justify a 2-3-hour uptake window when performing quantitative SPECT of the jawbone. Therefore, the minimum uptake time can potentially be reduced to only 2 hours.
  • Satonori Tsuneta, Kenichiro Suno, Yuichiro Fujieda, Masaya Watanabe, Shiro Watanabe, Kenji Hirata, Toshiyuki Nagai, Kohsuke Kudo
    Canadian Journal of Cardiology 2024/03 [Refereed][Not invited]
  • Junichi Nakagawa, Noriyuki Fujima, Kenji Hirata, Taisuke Harada, Naoto Wakabayashi, Yuki Takano, Akihiro Homma, Satoshi Kano, Kazuyuki Minowa, Kohsuke Kudo
    Japanese journal of radiology 2024/01/27 [Refereed][Not invited]
     
    PURPOSE: To develop a convolutional neural network (CNN) model to diagnose skull-base invasion by nasopharyngeal malignancies in CT images and evaluate the model's diagnostic performance. MATERIALS AND METHODS: We divided 100 malignant nasopharyngeal tumor lesions into a training (n = 70) and a test (n = 30) dataset. Two head/neck radiologists reviewed CT and MRI images and determined the positive/negative skull-base invasion status of each case (training dataset: 29 invasion-positive and 41 invasion-negative; test dataset: 13 invasion-positive and 17 invasion-negative). Preprocessing involved extracting continuous slices of the nasopharynx and clivus. The preprocessed training dataset was used for transfer learning with Residual Neural Networks 50 to create a diagnostic CNN model, which was then tested on the preprocessed test dataset to determine the invasion status and model performance. Original CT images from the test dataset were reviewed by a radiologist with extensive head/neck imaging experience (senior reader: SR) and another less-experienced radiologist (junior reader: JR). Gradient-weighted class activation maps (Grad-CAMs) were created to visualize the explainability of the invasion status classification. RESULTS: The CNN model's diagnostic accuracy was 0.973, significantly higher than those of the two radiologists (SR: 0.838; JR: 0.595). Receiver operating characteristic curve analysis gave an area under the curve of 0.953 for the CNN model (versus 0.832 and 0.617 for SR and JR; both p < 0.05). The Grad-CAMs suggested that the invasion-negative cases were present predominantly in bone marrow, while the invasion-positive cases exhibited osteosclerosis and nasopharyngeal masses. CONCLUSIONS: This CNN technique would be useful for CT-based diagnosis of skull-base invasion by nasopharyngeal malignancies.
  • Yoshifumi Mizuguchi, Motoki Nakao, Toshiyuki Nagai, Yuki Takahashi, Takahiro Abe, Shigeo Kakinoki, Shogo Imagawa, Kenichi Matsutani, Takahiko Saito, Masashige Takahashi, Yoshiya Kato, Hirokazu Komoriyama, Hikaru Hagiwara, Kenji Hirata, Takahiro Ogawa, Takuto Shimizu, Manabu Otsu, Kunihiro Chiyo, Toshihisa Anzai
    European Heart Journal - Digital Health 2023/12/20 [Refereed][Not invited]
     
    Abstract Aims Although frailty assessment is recommended for guiding treatment strategies and outcome prediction in elderly patients with heart failure (HF), most frailty scales are subjective and the scores vary among raters. We sought to develop a machine learning-based automatic rating method/system/model of the clinical frailty scale (CFS) for patients with HF. Methods and Results We prospectively examined 417 elderly (≥75 years) with symptomatic chronic HF patients from seven centers between January 2019 and October 2023. The patients were divided into derivation (n = 194) and validation (n = 223) cohorts. We obtained body-tracking motion data using a deep learning-based pose estimation library, on a smartphone camera. Predicted CFS was calculated from 128 key features, including gait parameters, using the Light Gradient Boosting Machine (LightGBM) model. To evaluate the performance of this model, we calculated Cohen’s weighted kappa (CWK) and intraclass correlation coefficient (ICC) between the predicted and actual CFSs. In the derivation and validation datasets, the LightGBM models showed excellent agreements between the actual and predicted CFSs (CWK 0.866, 95% CI 0.807-0.911; ICC 0.866, 95% CI 0.827-0.898; CWK 0.812, 95% CI 0.752-0.868; ICC 0.813, 95% CI 0.761-0.854, respectively). During a median follow-up period of 391 (IQR 273-617) days, the higher predicted CFS was independently associated with a higher risk of all-cause death (HR 1.60, 95% CI 1.02-2.50) after adjusting for significant prognostic covariates. Conclusion Machine learning-based algorithms of automatically CFS rating are feasible, and the predicted CFS is associated with the risk of all-cause death in elderly patients with HF.
  • Mariko Kawamura, Takeshi Kamomae, Masahiro Yanagawa, Koji Kamagata, Shohei Fujita, Daiju Ueda, Yusuke Matsui, Yasutaka Fushimi, Tomoyuki Fujioka, Taiki Nozaki, Akira Yamada, Kenji Hirata, Rintaro Ito, Noriyuki Fujima, Fuminari Tatsugami, Takeshi Nakaura, Takahiro Tsuboyama, Shinji Naganawa
    Journal of Radiation Research 0449-3060 2023/11/22 [Refereed][Invited]
     
    Abstract This review provides an overview of the application of artificial intelligence (AI) in radiation therapy (RT) from a radiation oncologist’s perspective. Over the years, advances in diagnostic imaging have significantly improved the efficiency and effectiveness of radiotherapy. The introduction of AI has further optimized the segmentation of tumors and organs at risk, thereby saving considerable time for radiation oncologists. AI has also been utilized in treatment planning and optimization, reducing the planning time from several days to minutes or even seconds. Knowledge-based treatment planning and deep learning techniques have been employed to produce treatment plans comparable to those generated by humans. Additionally, AI has potential applications in quality control and assurance of treatment plans, optimization of image-guided RT and monitoring of mobile tumors during treatment. Prognostic evaluation and prediction using AI have been increasingly explored, with radiomics being a prominent area of research. The future of AI in radiation oncology offers the potential to establish treatment standardization by minimizing inter-observer differences in segmentation and improving dose adequacy evaluation. RT standardization through AI may have global implications, providing world-standard treatment even in resource-limited settings. However, there are challenges in accumulating big data, including patient background information and correlating treatment plans with disease outcomes. Although challenges remain, ongoing research and the integration of AI technology hold promise for further advancements in radiation oncology.
  • Shiro Watanabe, Kenji Hirata, Keiichi Magota, Junki Takenaka, Naoto Wakabayashi, Daiki Shinyama, Koichi Yasuda, Akihiro Homma, Kohsuke Kudo
    Annals of nuclear medicine 2023/11/09 [Refereed][Not invited]
     
    OBJECTIVE: Silicon photomultiplier-based positron emission tomography/computed tomography (SiPM-PET/CT) has the superior spatial resolution to conventional PET/CT (cPET/CT). This head-to-head comparison study compared the images of physiological 18F-fluorodeoxyglucose (FDG) accumulation in small-volume structures between SiPM-PET/CT and cPET/CT in patients scanned with both modalities, and we investigated whether the thresholds that are reported to be useful for differentiating physiological accumulations from malignant lesions can also be applied to SiPM-PET/CT. METHODS: We enrolled 21 consecutive patients with head and neck malignancies who underwent whole-body FDG-PET/CT for initial staging or a follow-up evaluation (October 2020 to March 2022). After being injected with FDG, all patients underwent PET acquisition on both Vereos PET-CT and Gemini TF64 PET-CT systems (both Philips Healthcare) in random order. For each patient, the maximum standardized uptake value (SUVmax) was measured in the pituitary gland, esophagogastric junction (EGJ), adrenal glands, lumbar enlargement of the spinal cord, and epididymis. We measured the liver SUVmean and the blood pool SUVmean to calculate the target-to-liver ratio (TLR) and the target-to-blood ratio (TBR), respectively. Between-groups differences in each variable were examined by a paired t-test. We also investigated whether there were cases of target uptake greater than the reported threshold for distinguishing pathological from physiological accumulations. RESULTS: Data were available for 19 patients. Ten patients were in Group 1, i.e., the patients who underwent SiPM-PET first, and the remaining nine patients who underwent cPET first were in Group 2. In the SiPM-PET results, the SUVmax of all targets was significantly higher than that obtained by cPET in all patients, and this tendency was also observed when the patients were divided into Groups 1/2. The TLRs of all targets were significantly higher in SiPM-PET than in cPET in all patients, and SiPM-PET also showed significantly higher TBRs for all targets except the EGJ (p = 0.052). CONCLUSIONS: The physiological uptake in the small structures studied herein showed high accumulation on SiPM-PET. Our results also suggest that the thresholds reported for cPET to distinguish pathological accumulations likely lead to false-positive findings in SIPM-PET evaluations.
  • 腫瘍性骨軟化症における111Inペンテトレオチドを用いたソマトスタチン受容体シンチグラフィにてSPECT-CTが有用であった一例
    平野 佑亮, 平田 健司, 渡邊 史郎, 竹中 淳規, 孫田 惠一, 宗像 大和, 前田 佑介
    北海道放射線技術雑誌 (公社)日本放射線技術学会-北海道支部 (95) 39 - 39 0912-0327 2023/11
  • 労災疾病等医学研究令和5年度開始「じん肺」テーマについて
    大塚 義紀, 平田 健司, 唐 明輝, 中川 純一, 宇佐美 郁治, 岸本 卓巳, 水橋 啓一, 飯塚 幹也, 五十嵐 毅, 横山 多佳子, 木村 清延
    日本職業・災害医学会会誌 (一社)日本職業・災害医学会 71 (臨増) 別96 - 別96 1345-2592 2023/11
  • Junki Takenaka, Kenji Hirata, Shiro Watanabe, Masahiko Takahata, Kohsuke Kudo
    Clinical nuclear medicine 48 (11) e523-e525  2023/11/01 [Refereed][Not invited]
     
    MRI revealed a thoracic vertebrae lesion in a 40-year-old woman with back pain. She was referred to our institution; MRI demonstrated a mass from the second to the fifth thoracic vertebra and compression fractures. CT revealed a splenic mass, multiple pulmonary nodules, and low-density masses in the liver. 18 F-FDG PET/CT showed increased uptake (SUV max , 10.6) in the peripheral rim of the thoracic vertebra mass, with central parts showing lower uptake than the peripheral rim. The splenic mass exhibited increased accumulation (SUV max , 4.8). The thoracic spine lesion was fixed; a biopsy was performed. Alveolar echinococcosis was confirmed immunologically. Alveolar echinococcosis can present with bone lesions. It must be differentiated from malignancy.
  • Eitaro Kidera, Sho Koyasu, Kenji Hirata, Masatsugu Hamaji, Ryusuke Nakamoto, Yuji Nakamoto
    Annals of nuclear medicine 2023/09/27 [Refereed]
     
    PURPOSE: To develop a convolutional neural network (CNN)-based program to analyze maximum intensity projection (MIP) images of 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) positron emission tomography (PET) scans, aimed at predicting lymph node metastasis of non-small cell lung cancer (NSCLC), and to evaluate its effectiveness in providing diagnostic assistance to radiologists. METHODS: We obtained PET images of NSCLC from public datasets, including those of 435 patients with available N-stage information, which were divided into a training set (n = 304) and a test set (n = 131). We generated 36 maximum intensity projection (MIP) images for each patient. A residual network (ResNet-50)-based CNN was trained using the MIP images of the training set to predict lymph node metastasis. Lymph node metastasis in the test set was predicted by the trained CNN as well as by seven radiologists twice: first without and second with CNN assistance. Diagnostic performance metrics, including accuracy and prediction error (the difference between the truth and the predictions), were calculated, and reading times were recorded. RESULTS: In the test set, 67 (51%) patients exhibited lymph node metastases and the CNN yielded 0.748 predictive accuracy. With the assistance of the CNN, the prediction error was significantly reduced for six of the seven radiologists although the accuracy did not change significantly. The prediction time was significantly reduced for five of the seven radiologists with the median reduction ratio 38.0%. CONCLUSION: The CNN-based program could potentially assist radiologists in predicting lymph node metastasis by increasing diagnostic confidence and reducing reading time without affecting diagnostic accuracy, at least in the limited situations using MIP images.
  • Kenji Hirata, Koji Kamagata, Daiju Ueda, Masahiro Yanagawa, Mariko Kawamura, Takeshi Nakaura, Rintaro Ito, Fuminari Tatsugami, Yusuke Matsui, Akira Yamada, Yasutaka Fushimi, Taiki Nozaki, Shohei Fujita, Tomoyuki Fujioka, Takahiro Tsuboyama, Noriyuki Fujima, Shinji Naganawa
    Annals of nuclear medicine 2023/09/25 [Refereed][Invited]
     
    The radiopharmaceutical 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) has been dominantly used in positron emission tomography (PET) scans for over 20 years, and due to its vast utility its applications have expanded and are continuing to expand into oncology, neurology, cardiology, and infectious/inflammatory diseases. More recently, the addition of artificial intelligence (AI) has enhanced nuclear medicine diagnosis and imaging with FDG-PET, and new radiopharmaceuticals such as prostate-specific membrane antigen (PSMA) and fibroblast activation protein inhibitor (FAPI) have emerged. Nuclear medicine therapy using agents such as [177Lu]-dotatate surpasses conventional treatments in terms of efficacy and side effects. This article reviews recently established evidence of FDG and non-FDG drugs and anticipates the future trajectory of nuclear medicine.
  • Junki Takenaka, Shiro Watanabe, Takashige Abe, Takahiro Tsuchikawa, Satoshi Takeuchi, Kenji Hirata, Rina Kimura, Naoto Wakabayashi, Nobuo Shinohara, Kohsuke Kudo
    Neuroendocrinology 2023/09/19 
    Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumours that produce catecholamines. [131I] MIBG-avid unresectable or metastatic PPGLs are treated with [131I] MIBG therapy. A high metabolic tumour volume (MTV) and total lesion glycolysis (TLG) can be poor prognostic factors. Therefore, we evaluated the metabolic responses to [131I] MIBG therapy with respect to other clinical factors.A retrospective study was performed on a series of 20 patients who underwent FDG-PET before and after [131I] MIBG therapy. We administered a single dose comprising 5.5 GBq of [131I] MIBG. Semi-quantitative parameters (SUVmax, MTV, and TLG) were calculated using the liver SUV (mean + 3SD) as a threshold on Metavol software. The semi-quantitative FDG-PET parameters for determining response were complete response , partial remission, stable disease, and progressive disease (PD). We divided our study participants into the PD and non-PD groups and compared the overall survival between the two groups. Subsequently, we evaluated the relationships between metabolic response and age, sex, tumour type, metastatic site, chemotherapy or external radiation history, and 24-hour urine catecholamine levels by univariate logistic regression analyses. Both MTV-based and TLG-based criteria for PD vs. non-PD were significant prognostic factors (p = 0.014). However, treatment response as evaluated based on the SUVmax was not a significant predictor. Higher urinary dopamine levels were associated with poor metabolic response as assessed by MTV and TLG. The other clinical parameters were non-significant. Poor metabolic response (measured with MTV and TLG) to [131I] MIBG therapy in unresectable or metastatic PPGLs was related to shorter OS. The poor metabolic response can be predicted using the urinary dopamine level.
  • Masahiro Yanagawa, Rintaro Ito, Taiki Nozaki, Tomoyuki Fujioka, Akira Yamada, Shohei Fujita, Koji Kamagata, Yasutaka Fushimi, Takahiro Tsuboyama, Yusuke Matsui, Fuminari Tatsugami, Mariko Kawamura, Daiju Ueda, Noriyuki Fujima, Takeshi Nakaura, Kenji Hirata, Shinji Naganawa
    La Radiologia medica 128 (10) 1236 - 1249 2023/08/28 [Refereed][Invited]
     
    Although there is no solid agreement for artificial intelligence (AI), it refers to a computer system with intelligence similar to that of humans. Deep learning appeared in 2006, and more than 10 years have passed since the third AI boom was triggered by improvements in computing power, algorithm development, and the use of big data. In recent years, the application and development of AI technology in the medical field have intensified internationally. There is no doubt that AI will be used in clinical practice to assist in diagnostic imaging in the future. In qualitative diagnosis, it is desirable to develop an explainable AI that at least represents the basis of the diagnostic process. However, it must be kept in mind that AI is a physician-assistant system, and the final decision should be made by the physician while understanding the limitations of AI. The aim of this article is to review the application of AI technology in diagnostic imaging from PubMed database while particularly focusing on diagnostic imaging in thorax such as lesion detection and qualitative diagnosis in order to help radiologists and clinicians to become more familiar with AI in thorax.
  • Daiju Ueda, Taichi Kakinuma, Shohei Fujita, Koji Kamagata, Yasutaka Fushimi, Rintaro Ito, Yusuke Matsui, Taiki Nozaki, Takeshi Nakaura, Noriyuki Fujima, Fuminari Tatsugami, Masahiro Yanagawa, Kenji Hirata, Akira Yamada, Takahiro Tsuboyama, Mariko Kawamura, Tomoyuki Fujioka, Shinji Naganawa
    Japanese journal of radiology 2023/08/04 [Refereed][Invited]
     
    In this review, we address the issue of fairness in the clinical integration of artificial intelligence (AI) in the medical field. As the clinical adoption of deep learning algorithms, a subfield of AI, progresses, concerns have arisen regarding the impact of AI biases and discrimination on patient health. This review aims to provide a comprehensive overview of concerns associated with AI fairness; discuss strategies to mitigate AI biases; and emphasize the need for cooperation among physicians, AI researchers, AI developers, policymakers, and patients to ensure equitable AI integration. First, we define and introduce the concept of fairness in AI applications in healthcare and radiology, emphasizing the benefits and challenges of incorporating AI into clinical practice. Next, we delve into concerns regarding fairness in healthcare, addressing the various causes of biases in AI and potential concerns such as misdiagnosis, unequal access to treatment, and ethical considerations. We then outline strategies for addressing fairness, such as the importance of diverse and representative data and algorithm audits. Additionally, we discuss ethical and legal considerations such as data privacy, responsibility, accountability, transparency, and explainability in AI. Finally, we present the Fairness of Artificial Intelligence Recommendations in healthcare (FAIR) statement to offer best practices. Through these efforts, we aim to provide a foundation for discussing the responsible and equitable implementation and deployment of AI in healthcare.
  • Noriyuki Fujima, Koji Kamagata, Daiju Ueda, Shohei Fujita, Yasutaka Fushimi, Masahiro Yanagawa, Rintaro Ito, Takahiro Tsuboyama, Mariko Kawamura, Takeshi Nakaura, Akira Yamada, Taiki Nozaki, Tomoyuki Fujioka, Yusuke Matsui, Kenji Hirata, Fuminari Tatsugami, Shinji Naganawa
    Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine 22 (4) 401 - 414 2023/08/01 [Refereed][Invited]
     
    Due primarily to the excellent soft tissue contrast depictions provided by MRI, the widespread application of head and neck MRI in clinical practice serves to assess various diseases. Artificial intelligence (AI)-based methodologies, particularly deep learning analyses using convolutional neural networks, have recently gained global recognition and have been extensively investigated in clinical research for their applicability across a range of categories within medical imaging, including head and neck MRI. Analytical approaches using AI have shown potential for addressing the clinical limitations associated with head and neck MRI. In this review, we focus primarily on the technical advancements in deep-learning-based methodologies and their clinical utility within the field of head and neck MRI, encompassing aspects such as image acquisition and reconstruction, lesion segmentation, disease classification and diagnosis, and prognostic prediction for patients presenting with head and neck diseases. We then discuss the limitations of current deep-learning-based approaches and offer insights regarding future challenges in this field.
  • Satoshi Takeuchi, Kenji Hirata, Keiichi Magota, Shiro Watanabe, Rika Moku, Akihiko Shiiya, Jun Taguchi, Shin Ariga, Tomohiro Goda, Yoshihito Ohhara, Takurou Noguchi, Yasushi Shimizu, Ichiro Kinoshita, Rio Honma, Yasushi Tsuji, Akihiro Homma, Hirotoshi Dosaka-Akita
    EJNMMI research 13 (1) 69 - 69 2023/07/17 [Refereed][Not invited]
     
    BACKGROUND: Lenvatinib is widely used to treat unresectable and advanced thyroid carcinomas. We aimed to determine whether 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) performed 1 week after lenvatinib treatment initiation could predict treatment outcomes. RESULTS: This was a prospective, nonrandomised, multicentre study. Patients with pathologically confirmed differentiated thyroid carcinoma (DTC) and lesions refractory to radioiodine treatment were eligible for inclusion. Patients were treated with 24 mg lenvatinib as the initial dose and underwent PET/CT examination 1 week after treatment initiation. Contrast-enhanced CT was scheduled at least 4 weeks later as the gold standard for evaluation. The primary endpoint was to evaluate the discrimination power of maximum standardised uptake value (SUVmax) obtained by PET/CT compared to that obtained by contrast-enhanced CT. Evaluation was performed using the area under the receiver operating characteristic (ROC-AUC) curve. Twenty-one patients were included in this analysis. Receiver operating characteristic (ROC) curve analysis yielded an AUC of 0.714 for SUVmax after 1 week of lenvatinib treatment. The best cut-off value for the treatment response for SUVmax was 15.211. The sensitivity and specificity of this cut-off value were 0.583 and 0.857, respectively. The median progression-free survival was 26.3 months in patients with an under-cut-off value and 19.7 months in patients with an over-cut-off value (P = 0.078). CONCLUSIONS: The therapeutic effects of lenvatinib were detected earlier than those of CT because of decreased FDG uptake on PET/CT. PET/CT examination 1 week after the initiation of lenvatinib treatment may predict treatment outcomes in patients with DTC. TRIAL REGISTRATION: This trial was registered in the University Hospital Medical Information Network (UMIN) Clinical Trials Registry (number UMIN000022592) on 6 June, 2016.
  • Fuminari Tatsugami, Takeshi Nakaura, Masahiro Yanagawa, Shohei Fujita, Koji Kamagata, Rintaro Ito, Mariko Kawamura, Yasutaka Fushimi, Daiju Ueda, Yusuke Matsui, Akira Yamada, Noriyuki Fujima, Tomoyuki Fujioka, Taiki Nozaki, Takahiro Tsuboyama, Kenji Hirata, Shinji Naganawa
    Diagnostic and interventional imaging 2023/07/04 
    Recent advances in artificial intelligence (AI) for cardiac computed tomography (CT) have shown great potential in enhancing diagnosis and prognosis prediction in patients with cardiovascular disease. Deep learning, a type of machine learning, has revolutionized radiology by enabling automatic feature extraction and learning from large datasets, particularly in image-based applications. Thus, AI-driven techniques have enabled a faster analysis of cardiac CT examinations than when they are analyzed by humans, while maintaining reproducibility. However, further research and validation are required to fully assess the diagnostic performance, radiation dose-reduction capabilities, and clinical correctness of these AI-driven techniques in cardiac CT. This review article presents recent advances of AI in the field of cardiac CT, including deep-learning-based image reconstruction, coronary artery motion correction, automatic calcium scoring, automatic epicardial fat measurement, coronary artery stenosis diagnosis, fractional flow reserve prediction, and prognosis prediction, analyzes current limitations of these techniques and discusses future challenges.
  • パーキンソン病脳深部刺激療法術後5年目における治療有効性の評価
    白井 慎一, 江口 克紀, 山崎 和義, 松島 理明, 川堀 真人, 平田 健司, 藤村 幹, 矢部 一郎
    パーキンソン病・運動障害疾患コングレスプログラム・抄録集 Movement Disorder Society of Japan (MDSJ) 17回 86 - 86 2023/07
  • Kohei Nakajima, Akiyo Sugikawa, Hironobu Yasui, Kei Higashikawa, Chie Suzuki, Takahiro Natsume, Motofumi Suzuki, Hideo Takakura, Mayu Tomita, Sachi Takahashi, Kenji Hirata, Yasuhiro Magata, Yuji Kuge, Mikako Ogawa
    Molecular Imaging and Biology 1536-1632 2023/05/16 [Refereed][Not invited]
  • Akira Yamada, Koji Kamagata, Kenji Hirata, Rintaro Ito, Takeshi Nakaura, Daiju Ueda, Shohei Fujita, Yasutaka Fushimi, Noriyuki Fujima, Yusuke Matsui, Fuminari Tatsugami, Taiki Nozaki, Tomoyuki Fujioka, Masahiro Yanagawa, Takahiro Tsuboyama, Mariko Kawamura, Shinji Naganawa
    La Radiologia medica 2023/05/10 
    This review outlines the current status and challenges of the clinical applications of artificial intelligence in liver imaging using computed tomography or magnetic resonance imaging based on a topic analysis of PubMed search results using latent Dirichlet allocation. LDA revealed that "segmentation," "hepatocellular carcinoma and radiomics," "metastasis," "fibrosis," and "reconstruction" were current main topic keywords. Automatic liver segmentation technology using deep learning is beginning to assume new clinical significance as part of whole-body composition analysis. It has also been applied to the screening of large populations and the acquisition of training data for machine learning models and has resulted in the development of imaging biomarkers that have a significant impact on important clinical issues, such as the estimation of liver fibrosis, recurrence, and prognosis of malignant tumors. Deep learning reconstruction is expanding as a new technological clinical application of artificial intelligence and has shown results in reducing contrast and radiation doses. However, there is much missing evidence, such as external validation of machine learning models and the evaluation of the diagnostic performance of specific diseases using deep learning reconstruction, suggesting that the clinical application of these technologies is still in development.
  • Hideki Goto, Toshio Kitawaki, Nobuharu Fujii, Koji Kato, Yasushi Onishi, Noriko Fukuhara, Takuji Yamauchi, Kazunori Toratani, Hiroki Kobayashi, Shota Yoshida, Masatoshi Shimo, Koichi Onodera, Hajime Senjo, Masahiro Onozawa, Kenji Hirata, Isao Yokota, Takanori Teshima
    International journal of clinical oncology 28 (6) 816 - 826 2023/04/18 [Refereed][Not invited]
     
    BACKGROUND: Tisagenlecleucel, an autologous CD19-directed T-cell immunotherapy, can induce a durable response in adult patients with relapsed/refractory (r/r) B-cell lymphoma. METHODS: To elucidate the outcome of chimeric antigen receptor (CAR) T-cell therapy in Japanese, we retrospectively analyzed the outcomes of 89 patients who received tisagenlecleucel for r/r diffuse large B-cell lymphoma (n = 71) or transformed follicular lymphoma (n = 18). RESULTS: With a median follow-up of 6.6-months, 65 (73.0%) patients achieved a clinical response. The overall survival (OS) and event-free survival (EFS) rates at 12 months were 67.0% and 46.3%, respectively. Overall, 80 patients (89.9%) had cytokine release syndrome (CRS), and 6 patients (6.7%) had a grade ≥ 3 event. ICANS occurred in 5 patients (5.6%); only 1 patient had grade 4 ICANS. Representative infectious events of any grade were cytomegalovirus viremia, bacteremia and sepsis. The most common other adverse events were ALT elevation, AST elevation, diarrhea, edema, and creatinine elevation. No treatment-related mortality was observed. A Sub-analysis showed that a high metabolic tumor volume (MTV; ≥ 80 ml) and stable disease /progressive disease before tisagenlecleucel infusion were both significantly associated with a poor EFS and OS in a multivariate analysis (P < 0.05). Notably, the combination of these 2 factors efficiently stratified the prognosis of these patients (HR 6.87 [95% CI 2.4-19.65; P < 0.05] into a high-risk group). CONCLUSION: We report the first real-world data on tisagenlecleucel for r/r B-cell lymphoma in Japan. Tisagenlecleucel is feasible and effective, even in late line treatment. In addition, our results support a new algorithm for predicting the outcomes of tisagenlecleucel.
  • Sunburst appearanceを呈する頭蓋骨腫瘤を契機に発見された神経芽腫の1例
    北川 悠, 竹中 淳規, 渡邊 史郎, 平田 健司, 内山 裕子, 木村 理奈, 中川 純一, 池辺 洋平, 長谷河 昌孝, 澤井 彩織, 寺下 友佳代, 杉山 未奈子, 平林 真介, 長 祐子, 山口 秀, 真部 淳, 工藤 與亮
    北海道放射線医学雑誌 (NPO)メディカルイメージラボ 3 33 - 36 2023/03 [Refereed][Not invited]
     
    症例は9歳女児。左頭部腫瘤を主訴に近医を受診し、頭部CTで左前頭骨にsunburst appearanceを呈する腫瘤性病変を指摘され、その他にも右頭頂骨と左下顎頭に骨病変を認めた。体幹部造影CTを施行したところ、後縦隔の胸椎椎体前方から左側にかけて巨大な軟部腫瘤を認めた。血清神経特異エノラーゼ(NSE)や尿中バニリルマンデル酸(VMA)/ホモバニリン酸(HVA)が高値であり、神経芽腫が第一に疑われた。123I-MIBGシンチグラフィを施行したところ、後縦隔腫瘤のほか頭蓋骨を含めた全身骨にも集積が見られ、神経芽腫とその骨転移が疑われた。頭蓋骨腫瘤の生検術により神経芽腫の診断が確定した。神経芽腫は小児期に発生する頭蓋外の固形悪性腫瘍の中で最も頻度が高い。転移性頭蓋骨腫瘍がsunburst appearanceを呈することは比較的稀であるが、小児では神経芽腫の転移でしばしば経験される。神経芽腫の骨転移の部位として、頭蓋骨は頻度が高く、小児においてsunburst appearanceを呈し多発する頭蓋骨腫瘤を見た場合には神経芽腫の骨転移を考慮する必要がある。(著者抄録)
  • 西山 佳宏, 沖崎 貴琢, 乾 好貴, 大塚 秀樹, 高浪 健太郎, 中條 正豊, 中谷 航也, 野上 宗伸, 平田 健司, 前田 幸人, 吉村 真奈, 若林 大志, (公社)日本アイソトープ協会医学・薬学部会全国核医学診療実態調査専門委員会
    Radioisotopes (公社)日本アイソトープ協会 72 (1) 49 - 100 0033-8303 2023/03 
    日本アイソトープ協会では1982年から5年ごとに専門委員会を設けて全国核医学診療実態調査を行っており,第9回調査を2022年6月に行った。回答回収率は90%超であった。年間推定検査件数は単光子放出核種を用いた核医学検査が前回より2.7%増加した一方で,PET検査は約1.5%減少した。この結果,核医学検査総数は1.0%増加した。非密封RIを用いた核医学治療は131I-MIBGによる褐色細胞腫・パラガングリオーマや177Lu-ルテチウムオキソドトレオチドによる神経内分泌腫瘍の治療が新規に開始されたが,223Raと131Iを用いた治療件数の減少や一部薬剤の供給停止もあり,全体で17.7%減少した。核医学検査の総数はあまり変わらないが,核医学治療が大きく変化していることが示された。(著者抄録)
  • Nagara Tamaki, Kenji Hirata, Tomoya Kotani, Yoshitomo Nakai, Shigenori Matsushima, Kei Yamada
    Japanese Journal of Radiology 41 (8) 831 - 842 1867-1071 2023/03 [Refereed]
     
    Abstract Positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) has been commonly used in many oncological areas. High-resolution PET permits a three-dimensional analysis of FDG distributions on various lesions in vivo, which can be applied for tissue characterization, risk analysis, and treatment monitoring after chemoradiotherapy and immunotherapy. Metabolic changes can be assessed using the tumor absolute FDG uptake as standardized uptake value (SUV) and metabolic tumor volume (MTV). In addition, tumor heterogeneity assessment can potentially estimate tumor aggressiveness and resistance to chemoradiotherapy. Attempts have been made to quantify intratumoral heterogeneity using radiomics. Recent reports have indicated the clinical feasibility of a dynamic FDG PET-computed tomography (CT) in pilot cohort studies of oncological cases. Dynamic imaging permits the assessment of temporal changes in FDG uptake after administration, which is particularly useful for differentiating pathological from physiological uptakes with high diagnostic accuracy. In addition, several new parameters have been introduced for the in vivo quantitative analysis of FDG metabolic processes. Thus, a four-dimensional FDG PET-CT is available for precise tissue characterization of various lesions. This review introduces various new techniques for the quantitative analysis of FDG distribution and glucose metabolism using a four-dimensional FDG analysis with PET-CT. This elegant study reveals the important role of tissue characterization and treatment strategies in oncology.
  • MIP類似アルゴリズムによるFDG-PET体表画像の有用性
    平田 健司, 木村 理奈, 唐 明輝, 渡邊 史郎, 竹中 淳規, 若林 直人, 杉森 博行, 吉村 高明, 工藤 與亮
    核医学 (一社)日本核医学会 60 (Suppl.) S208 - S208 0022-7854 2023
  • SRCNNを用いた短時間収集PET画像の画質改善モデルの開発と定量性評価
    遠藤 大輝, 吉村 高明, 唐 明輝, 杉森 博行, 長谷川 淳, 小亀 翔揮, 孫田 惠一, 木村 理奈, 渡邊 史郎, 平田 健司, 工藤 與亮
    核医学 (一社)日本核医学会 60 (Suppl.) S209 - S209 0022-7854 2023
  • 切除不能/転移性PPGLにおける初回I-131MIBG治療による総糖代謝量の変化と予後の関係性の解析
    竹中 淳規, 渡邊 史郎, 安部 崇重, 土川 貴裕, 竹内 啓, 平田 健司, 木村 理奈, 若林 直人, 篠原 信雄, 工藤 與亮
    核医学 (一社)日本核医学会 60 (Suppl.) S216 - S216 0022-7854 2023
  • 褐色細胞腫・傍神経節腫に対するI-131MIBG治療の単回投与と複数回投与での有害事象発生率の検討
    若林 直人, 渡邊 史郎, 安部 崇重, 竹中 淳規, 平田 健司, 篠原 信雄, 工藤 與亮
    核医学 (一社)日本核医学会 60 (Suppl.) S216 - S216 0022-7854 2023
  • Junki Takenaka, Kenji Hirata, Shiro Watanabe, Hideaki Shiraishi, Kohsuke Kudo
    Asia Oceania journal of nuclear medicine & biology 11 (1) 93 - 96 2023 
    A 2-year-old girl started to wobble without any specific triggers, so the patient was admitted to our hospital's pediatric department. The entire cerebellum showed severe atrophy on MRI and much lower uptake than that in the cerebral cortex on perfusion SPECT. The diagnosis of opsoclonus-myoclonus syndrome (OMS) was suspected. MRI visualized a small mass behind the inferior vena cava. Although its uptake on I-123 MIBG scintigraphy was inconclusive, the mass was surgically removed, and the diagnosis of neuroblastoma was pathologically confirmed. OMS is one of the paraneoplastic neurological syndromes with cerebellar ataxia, myoclonus of the trunk and extremities, and opsoclonus as its main symptoms. Approximately 50% of children cases with OMS are associated with neuroblastoma. The prognosis for neuroblastoma itself with OMS is relatively good, but the neurological prognosis is very poor. If there is decreased blood flow in the cerebellum of an infant, it may be necessary to search for neuroblastoma.
  • MIP類似アルゴリズムによるFDG-PET体表画像の有用性
    平田 健司, 木村 理奈, 唐 明輝, 渡邊 史郎, 竹中 淳規, 若林 直人, 杉森 博行, 吉村 高明, 工藤 與亮
    核医学 (一社)日本核医学会 60 (Suppl.) S208 - S208 0022-7854 2023
  • SRCNNを用いた短時間収集PET画像の画質改善モデルの開発と定量性評価
    遠藤 大輝, 吉村 高明, 唐 明輝, 杉森 博行, 長谷川 淳, 小亀 翔揮, 孫田 惠一, 木村 理奈, 渡邊 史郎, 平田 健司, 工藤 與亮
    核医学 (一社)日本核医学会 60 (Suppl.) S209 - S209 0022-7854 2023
  • Tsubasa Kunieda, Ren Togo, Noriko Nishioka, Yukie Shimizu, Shiro Watanabe, Kenji Hirata, Keisuke Maeda, Takahiro Ogawa 0001, Kohsuke Kudo, Miki Haseyama
    ICCE-Taiwan 165 - 166 2023
  • Junki Takenaka, Shiro Watanabe, Takashige Abe, Kenji Hirata, Yuko Uchiyama, Rina Kimura, Nobuo Shinohara, Kohsuke Kudo
    Annals of nuclear medicine 2022/10/27 [Refereed][Not invited]
     
    OBJECTIVE: Pheochromocytomas and paragangliomas (PPGLs) are rare tumors arising from the neural crest cells that form the sympathetic and parasympathetic nervous systems. Radiotherapy with [131I]metaiodobenzylguanidine (MIBG) is recommended for unresectable PPGLs. We investigated the usefulness of the metabolic tumor volume (MTV) and total lesion glycolysis (TLG) derived from [18F]fluorodeoxyglucose-positron emission tomography (FDG-PET) for predicting the prognosis of patients with unresectable PPGL(s) before receiving [131I]MIBG therapy. PATIENTS AND METHODS: We retrospectively analyzed the cases of 25 patients with unresectable PPGLs treated with [131I]MIBG at our hospital between 2001 and 2020. The MTV and TLG were measured in reference to liver accumulation. We divided the patients into two groups based on median values for the maximum standardized uptake value (SUVmax), MTV, and TLG, and evaluated between-group differences using log-rank tests. Cox proportional hazards models were used to determine whether there were significant differences in prognosis with respect to tumor type (pheochromocytoma vs. paraganglioma), site of metastasis, age, past treatment (chemotherapy, external radiation or [131I]MIBG treatment before the current [131I]MIBG treatment), urinary catecholamine, SUVmax, MTV, and TLG. RESULTS: The median follow-up time was 42 months (range 2-136 months). The median overall survival was 63 months. The overall survival (OS) was significantly shorter in the high-MTV group (log-rank test, p = 0.049) and the high-TLG group (p = 0.049), with no significant difference between the high- and low-SUVmax groups (p = 0.19). Likewise, there was no significant difference in prognosis according to pheochromocytoma or paraganglioma, metastasis location, age, or prior chemotherapy. A history of external radiation before [131I]MIBG treatment was associated with a significantly worse prognosis (hazard ration [HR] = 7.95, p = 0.0018). Urinary adrenaline and noradrenaline were not significant prognostic factors (p = 0.70, p = 0.25, respectively), but urinary dopamine did predict a worse outcome (p = 0.022). There was no increased risk of death for higher SUVmax or TLG (p = 0.63 and 0.057, respectively), but higher MTV did predict a worse outcome (HR = 7.27, p = 0.029). CONCLUSION: High MTV and high TLG were significantly associated with a poor prognosis after [131I]MIBG therapy for PPGLs. Other treatment strategies for such patients may need to be explored.
  • Yoko Satoh, Masamichi Imai, Chihiro Ikegawa, Kenji Hirata, Norifumi Abo, Mao Kusuzaki, Noriko Oyama-Manabe, Hiroshi Onishi
    Annals of nuclear medicine 36 (12) 1010 - 1018 2022/10/08 [Refereed][Not invited]
     
    OBJECTIVE: Semi-quantitative positron emission tomography (PET) values, such as the maximum standardized uptake value (SUVmax), are widely used to identify malignant lesions and evaluate the response to treatment. The image quality of ring-shaped dedicated breast positron emission tomography (dbPET) has been known to decrease the closer it is to the detector's edge. This study aimed to investigate the effect of radioactivity (RI) outside the detector field of view (FOV) on the image quality of the ring-shaped dbPET. METHODS: A breast phantom containing the left myocardium, which was prepared using a 3D printer, filled with 18F-fluorodeoxyglucose (FDG) solution with various RI concentration ratios (RCRs) of myocardium to background and scanned with the edge of an apex positioned exactly in line with the edge of the FOV of the dbPET scanner. The phantom image quality was visually and quantitatively evaluated. Following the phantom study, left-right breast differences (the left breast uptake ratio to the right breast (LUR)) on clinical dbPET images of 74 women were quantitatively evaluated. The relationships between these parameters, clinical indices, and FDG uptake in the left myocardium on PET/computed tomography (CT) images were analyzed. RESULTS: The phantom study showed that the higher the RCR of the myocardium and the closer it is to the top edge of the phantom, the higher is the pixel value of the dbPET images. In a clinical study, LUR was significantly correlated with myocardial SUVmax (r = 0.96, p < 0.0001) and metabolic myocardial volume (r = 0.63, p = 0.001) for whole-body PET/CT imaging. Although no significant correlations were found between LUR and age (r = 0.05, p = 0.6865), body mass index (r = 0.03, p = 0.8178), or distance between the left myocardial apex and chest wall (r = 0.16, p = 0.1667). CONCLUSIONS: FDG uptake in the myocardium affected dbPET images of the left breast, especially near the chest wall. Further, the effect of RI outside the FOV, such as in the myocardium, must be considered in the quantitative evaluation of breast cancer using dbPET.
  • Junichi Nakagawa, Noriyuki Fujima, Kenji Hirata, Minghui Tang, Satonori Tsuneta, Jun Suzuki, Taisuke Harada, Yohei Ikebe, Akihiro Homma, Satoshi Kano, Kazuyuki Minowa, Kohsuke Kudo
    Cancer imaging : the official publication of the International Cancer Imaging Society 22 (1) 52 - 52 2022/09/22 
    BACKGROUND: In nasal or sinonasal tumors, orbital invasion beyond periorbita by the tumor is one of the important criteria in the selection of the surgical procedure. We investigated the usefulness of the convolutional neural network (CNN)-based deep learning technique for the diagnosis of orbital invasion, using computed tomography (CT) images. METHODS: A total of 168 lesions with malignant nasal or sinonasal tumors were divided into a training dataset (n = 119) and a test dataset (n = 49). The final diagnosis (invasion-positive or -negative) was determined by experienced radiologists who carefully reviewed all of the CT images. In a CNN-based deep learning analysis, a slice of the square target region that included the orbital bone wall was extracted and fed into a deep-learning training session to create a diagnostic model using transfer learning with the Visual Geometry Group 16 (VGG16) model. The test dataset was subsequently tested in CNN-based diagnostic models and by two other radiologists who were not specialized in head and neck radiology. At approx. 2 months after the first reading session, two radiologists again reviewed all of the images in the test dataset, referring to the diagnoses provided by the trained CNN-based diagnostic model. RESULTS: The diagnostic accuracy was 0.92 by the CNN-based diagnostic models, whereas the diagnostic accuracies by the two radiologists at the first reading session were 0.49 and 0.45, respectively. In the second reading session by two radiologists (diagnosing with the assistance by the CNN-based diagnostic model), marked elevations of the diagnostic accuracy were observed (0.94 and 1.00, respectively). CONCLUSION: The CNN-based deep learning technique can be a useful support tool in assessing the presence of orbital invasion on CT images, especially for non-specialized radiologists.
  • AIによる肝臓セグメンテーションの性能評価と肝臓体積の経時的変化
    木村 理奈, 平田 健司, 常田 慧徳, 竹中 淳規, 渡邊 史郎, 阿保 大介, 工藤 與亮
    日本医学放射線学会秋季臨床大会抄録集 (公社)日本医学放射線学会 59回 S403 - S403 0048-0428 2022/09
  • Yuji Nakamoto, Kazuhiro Kitajima, Akira Toriihara, Masatoyo Nakajo, Kenji Hirata
    Annals of Nuclear Medicine 36 (9) 798 - 803 0914-7187 2022/09
  • Shiro Watanabe, Shozo Okamoto, Kazumasa Akikawa, Noriyuki Miyamoto, Miyuki Okamura-Kawasaki, Yuko Uchiyama, Junki Takenaka, Takuya Toyonaga, Kenji Hirata, Kohsuke Kudo
    Annals of nuclear medicine 2022/08/16 
    OBJECTIVE: Radioactive iodine (RAI) therapy is a useful treatment for Graves' disease (GD). Most RAI sessions administer ≤ 500 MBq of iodine (I)-131. Sometimes patients require repeated RAI, often for longer periods of remission. We investigated the characteristics of patients for whom high dose (mostly 1110 MBq of I-131) RAI was effective as RAI therapy for GD. METHODS: We retrospectively analyzed the cases of 79 patients who underwent RAI for GD in a multicenter setting. We divided the patients into two groups based on the I-131 dose administered: the low dose (LD) group who received ≤ 500 MBq (n = 44) and the high dose (HD) group who received > 500 MBq (n = 35). The therapeutic effect was defined as achieving remission and reaching the point of participating in thyroid hormone replacement therapy within 1 year after RAI. We compared the LD and HD groups' remission rates and conducted a multivariate logistic regression analysis of predictive factors for remission. In a simulation, using the formula for predicting the probability of remission obtained from the analysis results, we estimated how much the remission rate would change if the I-131 dose is increased from 500 to 1110 MBq. RESULTS: The mean ± standard deviation I-131 dose administered in the LD group was 480 ± 6 MBq, and that of the HD group was 1054 ± 265 MBq. Thirty-five patients (80%) in the LD group and 26 patients (74%) in the HD group achieved remission; this difference in the remission rate was not significant. The multivariate analysis results demonstrated that the absorbed dose and thyroid-stimulating antibody (TSAb) were independent predictors of remission. Seven patients (8.9%) showed an increased probability of remission from < 50% to > 50% when the higher RAI dose was applied (1110 MBq instead of 500 MBq). The thyroid volume and TSAb values in these patients were relatively large at 54.7 ± 34.2 mL and 1378.4 ± 586.3%, respectively. CONCLUSION: Although the overall remission rate was not significantly different between the patients who received high- or low-dose I-131, treatment with high-dose RAI may improve the probability of remission in patients with a massive thyroid volume and/or high-TSAb Graves' disease.
  • バセドウ病に対するHigh dose I-131治療による治療効果の改善
    渡邊 史郎, 岡本 祥三, 秋川 和聖, 内山 裕子, 竹中 淳規, 平田 健司, 工藤 與亮
    核医学 (一社)日本核医学会 59 (Suppl.) S463 - S463 0022-7854 2022/08
  • 平田 健司, 竹中 淳規, 山口 秀, 志賀 哲, 豊永 拓哉, 工藤 與亮
    臨床放射線 金原出版(株) 67 (7) 683 - 692 0009-9252 2022/07
  • Kohei Nakajima, Mitsunori Homma, Motofumi Suzuki, Yuta Yokouchi, Takuma Matsuda, Hideo Takakura, Kenji Hirata, Yuji Kuge, Mikako Ogawa
    Nuclear Medicine and Biology 108-109 85 - 92 0969-8051 2022/05 [Refereed][Not invited]
     
    INTRODUCTION: Hypoxia is common in solid tumors and creates an immunosuppressive environment that leads to resistance to immunotherapy, such as an anti-programmed death receptor-1 (PD-1) therapy. It has been suggested that anti-PD-1 therapy may reduce tumor hypoxia by remodeling the tumor vasculature; however, it is unclear how anti-PD-1 therapy reduces hypoxia over time. Therefore, we investigated the relationship between hypoxia and immune activation by anti-PD-1 therapy in murine cancer models. METHODS: Anti-PD-1 antibody was injected to CT26- and MC38-tumor-bearing mice on days 0 and 5. Tumor hypoxia was non-invasively evaluated using positron emission tomography (PET) with [18F]fluoromisonidazole ([18F]FMISO) on days 3 and 7. Histological analysis was conducted to investigate the infiltration of immune cells in [18F]FMISO-accumulated hypoxic area. In addition, the immune cell population in tumors and the percentages of cancer and immune cells under hypoxic conditions were analyzed at single-cell level using flow cytometry. RESULTS: Flow cytometric analysis of CT26 tumors on day 3 showed that anti-PD-1 therapy reduced hypoxia without inhibition of tumor growth. In addition, the infiltration of CD8+ T cells was increased in treated tumors. In contrast to CT26 tumors, the percentage of hypoxic cells in MC38 tumors did not change on days 3 and 7, and there was minimal immune activation induced by anti-PD-1 antibody. Changes in hypoxia in CT26 tumors were not detected by [18F]FMISO-PET, but autoradiogram showed that [18F]FMISO accumulated in immunosuppressed areas, where the infiltration of immune cells was relatively low. CONCLUSION: Reduction of hypoxia was induced in CT26 tumor, in which adequate immune response to anti-PD-1 therapy was exhibited, at an early time point before suppression of tumor growth. Our findings suggest that anti-PD-1 therapy can create a tumor microenvironment that facilitates immune activation by reducing hypoxia.
  • Takaaki Yoshimura, Atsushi Hasegawa, Shoki Kogame, Keiichi Magota, Rina Kimura, Shiro Watanabe, Kenji Hirata, Hiroyuki Sugimori
    Diagnostics 12 (4) 872 - 872 2022/03/31 
    In positron emission tomography (PET) imaging, image quality correlates with the injected [18F]-fluorodeoxyglucose (FDG) dose and acquisition time. If image quality improves from short-acquisition PET images via the super-resolution (SR) deep learning technique, it is possible to reduce the injected FDG dose. Therefore, the aim of this study was to clarify whether the SR deep learning technique could improve the image quality of the 50%-acquisition-time image to the level of that of the 100%-acquisition-time image. One-hundred-and-eight adult patients were enrolled in this retrospective observational study. The supervised data were divided into nine subsets for nested cross-validation. The mean peak signal-to-noise ratio and structural similarity in the SR-PET image were 31.3 dB and 0.931, respectively. The mean opinion scores of the 50% PET image, SR-PET image, and 100% PET image were 3.41, 3.96, and 4.23 for the lung level, 3.31, 3.80, and 4.27 for the liver level, and 3.08, 3.67, and 3.94 for the bowel level, respectively. Thus, the SR-PET image was more similar to the 100% PET image and subjectively improved the image quality, as compared to the 50% PET image. The use of the SR deep-learning technique can reduce the injected FDG dose and thus lower radiation exposure.
  • 肺癌の再発・転移が疑われた後縦隔FDG陽性病変の診断に骨髄シンチグラフィが有用であった一例
    眞島 隆成, 竹中 淳規, 渡邊 史郎, 内山 裕子, 木村 理奈, 榊原 純, 平田 健司, 工藤 與亮
    北海道放射線医学雑誌 (NPO)メディカルイメージラボ 2 29 - 33 2022/03 
    後縦隔傍脊椎部に発生した髄外造血の一例を経験したので報告する。症例は70歳代男性。原発性肺癌の術後経過観察中に胸部CTにて第5/6胸椎腹側に軟部腫瘤の出現を指摘され、その後も腫瘤は増大傾向を示した。18F-FDG PET/CTでの集積亢進も認め、術後再発や転移性腫瘍、その他悪性リンパ腫や神経原性腫瘍等が鑑別となったが、画像経過からは腫瘤は経時的な増大とともに形態の変化も認めていた。この経過からは髄外造血が疑われたが、病変の局在としてはやや非典型であった。診断目的に気管支鏡下または外科的生検も検討されたが、出血リスクの高い髄外造血の除外のためインジウム(111In)シンチグラフィを施行したところ、腫瘤に一致したインジウムの集積を認め、髄外造血と診断した。その後も経過観察し、腫瘤は自然消退した。髄外造血は肝臓、脾臓、リンパ節などにみられるが、胸腔内、なかでも後縦隔の傍脊椎領域にも発生する。後縦隔傍脊椎部に腫瘤を認めた場合には髄外造血を念頭に置く必要があり、骨髄シンチグラフィにより侵襲的検査を回避可能な場合がある。(著者抄録)
  • 免疫チェックポイント阻害剤が腫瘍内の低酸素状態に及ぼす影響に関する検討
    本間 充憲, 中島 孝平, 鈴木 基史, 横内 勇太, 松田 拓真, 高倉 栄男, 平田 健司, 久下 裕司, 小川 美香子
    日本薬学会年会要旨集 (公社)日本薬学会 142年会 26H - pm06S 0918-9823 2022/03
  • 演繹法と帰納法の視点から見た医療AI
    平田 健司, 杉森 博行, 唐 明輝, 中谷 純, 小笠原 克彦, 豊永 拓哉, 工藤 與亮
    北海道放射線医学雑誌 (NPO)メディカルイメージラボ 2 1 - 6 2022/03 
    医療AIが目覚ましい発達を続けている。AIに関する明確な定義はないため、今回、医療従事者等に対してAIに関する意識調査を行った結果、AIであるかどうかの境界線は、機械学習の有無にありそうだということがわかった。機械学習は帰納法に基づく考え方であり、あらかじめ多数のデータを学習させておくことで、明示的にルールを与えずとも未知の事例を正しく判断させる手法である。画像分類においては明示的ルールを与えることが困難であるため、機械学習が威力を発揮する。第3次AIブームの現在、AIといえば機械学習に基づくAIのことを指すことが多い。これに対して、第1次、第2次AIブームでは推論、探索、エキスパートシステムといった演繹法に基づくAIが盛んに研究されたが成功せず、冬の時代を経験した。我々は、帰納法のみのAIではいずれ限界に到達する可能性があり、演繹法の手法をいかに組み合わせていくかが今後の課題になっていくと考えている。(著者抄録)
  • Anri Inaki, Tohru Shiga, Yoshito Tsushima, Megumi Jinguji, Hiroshi Wakabayashi, Daiki Kayano, Norihito Akatani, Takafumi Yamase, Yuji Kunita, Satoru Watanabe, Tomo Hiromasa, Hiroshi Mori, Kenji Hirata, Shiro Watanabe, Tetsuya Higuchi, Hiroyasu Tomonaga, Seigo Kinuya
    Annals of Nuclear Medicine 36 (3) 267 - 278 0914-7187 2022/03 [Refereed]
     
    Abstract Objective In this phase II study, we aimed to investigate the efficacy and safety of single-dose [131I]meta-iodobenzylguanidine (131I-mIBG) therapy in patients with refractory pheochromocytoma and paraganglioma (PPGL). Patients and methods This study was designed as an open-label, single-arm, multi-center, phase II clinical trial. The enrolled patients were administered 7.4 GBq of 131I-mIBG. Its efficacy was evaluated 12 and 24 weeks later, and its safety was monitored continuously until the end of the study. We evaluated the biochemical response rate as the primary endpoint using the one-sided exact binomial test based on the null hypothesis (≤ 5%). Results Seventeen patients were enrolled in this study, of which 16 were treated. The biochemical response rate (≥ 50% decrease in urinary catecholamines) was 23.5% (90% confidence interval: 8.5–46.1%, p = 0.009). The radiographic response rates, determined with CT/MRI according to the response evaluation criteria in solid tumors (RECIST) version 1.1 and 123I-mIBG scintigraphy were 5.9% (0.3%–25.0%) and 29.4% (12.4%–52.2%), respectively. The most frequent non-hematologic treatment-emergent adverse events (TEAEs) were gastrointestinal symptoms including nausea, appetite loss, and constipation, which were, together, observed in 15 of 16 patients. Hematologic TEAEs up to grade 3 were observed in 14 of 16 patients. No grade 4 or higher TEAEs were observed. All patients had experienced at least one TEAE, but no fatal or irreversible TEAEs were observed. Conclusion A single dose 131I-mIBG therapy was well tolerated by patients with PPGL, and statistically significantly reduced catecholamine levels compared to the threshold response rate, which may lead to an improved prognosis for these patients.
  • Kenji Hirata, Hiroyuki Sugimori, Noriyuki Fujima, Takuya Toyonaga, Kohsuke Kudo
    Annals of nuclear medicine 36 (2) 123 - 132 2022/01/14 [Refereed][Invited]
     
    As in all other medical fields, artificial intelligence (AI) is increasingly being used in nuclear medicine for oncology. There are many articles that discuss AI from the viewpoint of nuclear medicine, but few focus on nuclear medicine from the viewpoint of AI. Nuclear medicine images are characterized by their low spatial resolution and high quantitativeness. It is noted that AI has been used since before the emergence of deep learning. AI can be divided into three categories by its purpose: (1) assisted interpretation, i.e., computer-aided detection (CADe) or computer-aided diagnosis (CADx). (2) Additional insight, i.e., AI provides information beyond the radiologist's eye, such as predicting genes and prognosis from images. It is also related to the field called radiomics/radiogenomics. (3) Augmented image, i.e., image generation tasks. To apply AI to practical use, harmonization between facilities and the possibility of black box explanations need to be resolved.
  • Chie Tsuruta, Kenji Hirata, Kohsuke Kudo, Naoya Masumori, Masamitsu Hatakenaka
    European radiology experimental 6 (1) 1 - 1 2022/01/12 [Refereed][Not invited]
     
    BACKGROUND: We investigated the correlation between texture features extracted from apparent diffusion coefficient (ADC) maps or diffusion-weighted images (DWIs), and grade group (GG) in the prostate peripheral zone (PZ) and transition zone (TZ), and assessed reliability in repeated examinations. METHODS: Patients underwent 3-T pelvic magnetic resonance imaging (MRI) before radical prostatectomy with repeated DWI using b-values of 0, 100, 1,000, and 1,500 s/mm2. Region of interest (ROI) for cancer was assigned to the first and second DWI acquisition separately. Texture features of ROIs were extracted from comma-separated values (CSV) data of ADC maps generated from several sets of two b-value combinations and DWIs, and correlation with GG, discrimination ability between GG of 1-2 versus 3-5, and data repeatability were evaluated in PZ and TZ. RESULTS: Forty-four patients with 49 prostate cancers met the eligibility criteria. In PZ, ADC 10% and 25% based on ADC map of two b-value combinations of 100 and 1,500 s/mm2 and 10% based on ADC map with b-value of 0 and 1,500 s/mm2 showed significant correlation with GG, acceptable discrimination ability, and good repeatability. In TZ, higher-order texture feature of busyness extracted from ADC map of 100 and 1,500 s/mm2, and high gray-level run emphasis, short-run high gray-level emphasis, and high gray-level zone emphasis from DWI with b-value of 100 s/mm2 demonstrated significant correlation, excellent discrimination ability, but moderate repeatability. CONCLUSIONS: Some DWI-related features showed significant correlation with GG, acceptable to excellent discrimination ability, and moderate to good data repeatability in prostate cancer, and differed between PZ and TZ.
  • Tsubasa Kunieda, Ren Togo, Noriko Nishioka, Yukie Shimizu, Shiro Watanabe, Kenji Hirata, Keisuke Maeda, Takahiro Ogawa 0001, Kohsuke Kudo, Miki Haseyama
    GCCE 137 - 138 2022
  • Anri Inaki, Tohru Shiga, Yoshito Tsushima, Megumi Jinguji, Hiroshi Wakabayashi, Daiki Kayano, Norihito Akatani, Takafumi Yamase, Yuji Kunita, Satoru Watanabe, Tomo Hiromasa, Hiroshi Mori, Kenji Hirata, Shiro Watanabe, Tetsuya Higuchi, Hiroyasu Tomonaga, Seigo Kinuya
    Annals of nuclear medicine 36 (3) 267 - 278 2021/12/06 [Refereed][Not invited]
     
    OBJECTIVE: In this phase II study, we aimed to investigate the efficacy and safety of single-dose [131I]meta-iodobenzylguanidine (131I-mIBG) therapy in patients with refractory pheochromocytoma and paraganglioma (PPGL). PATIENTS AND METHODS: This study was designed as an open-label, single-arm, multi-center, phase II clinical trial. The enrolled patients were administered 7.4 GBq of 131I-mIBG. Its efficacy was evaluated 12 and 24 weeks later, and its safety was monitored continuously until the end of the study. We evaluated the biochemical response rate as the primary endpoint using the one-sided exact binomial test based on the null hypothesis (≤ 5%). RESULTS: Seventeen patients were enrolled in this study, of which 16 were treated. The biochemical response rate (≥ 50% decrease in urinary catecholamines) was 23.5% (90% confidence interval: 8.5-46.1%, p = 0.009). The radiographic response rates, determined with CT/MRI according to the response evaluation criteria in solid tumors (RECIST) version 1.1 and 123I-mIBG scintigraphy were 5.9% (0.3%-25.0%) and 29.4% (12.4%-52.2%), respectively. The most frequent non-hematologic treatment-emergent adverse events (TEAEs) were gastrointestinal symptoms including nausea, appetite loss, and constipation, which were, together, observed in 15 of 16 patients. Hematologic TEAEs up to grade 3 were observed in 14 of 16 patients. No grade 4 or higher TEAEs were observed. All patients had experienced at least one TEAE, but no fatal or irreversible TEAEs were observed. CONCLUSION: A single dose 131I-mIBG therapy was well tolerated by patients with PPGL, and statistically significantly reduced catecholamine levels compared to the threshold response rate, which may lead to an improved prognosis for these patients.
  • SiPM-PET/CT装置を用いた冠動脈18F-FDG集積の再現性評価
    渡邊 史郎, 納谷 昌直, 孫田 恵一, 真鍋 治, 新山 大樹, 平田 健司, 内山 裕子, 竹中 淳規, 工藤 與亮
    核医学 (一社)日本核医学会 58 (Suppl.) S210 - S210 0022-7854 2021/10
  • FDG-PET/CTのレポート上のSUVmaxを利用して解剖学用語を機械学習させる検討
    平田 健司, 渡邊 史郎, 内山 裕子, 竹中 淳規, 木村 理奈, 眞島 隆成, 孫田 恵一, 工藤 與亮
    核医学 (一社)日本核医学会 58 (Suppl.) S225 - S225 0022-7854 2021/10
  • 待機時間2時間は充分か 顎骨SPECT定量解析における撮像待機時間の研究
    秦 浩信, 下村 悟史, 今待 賢治, 舩山 恭祐, 浅香 卓哉, 佐藤 淳, 平田 健司, 松坂 方士, 盛 洋一, 南部 敏和, 北川 善政
    核医学 (一社)日本核医学会 58 (Suppl.) S216 - S216 0022-7854 2021/10
  • Toshiki Terao, Youichi Machida, Kenji Hirata, Ayumi Kuzume, Rikako Tabata, Takafumi Tsushima, Daisuke Miura, Kentaro Narita, Masami Takeuchi, Ukihide Tateishi, Kosei Matsue
    Clinical nuclear medicine 46 (10) 790 - 796 2021/10/01 [Refereed][Not invited]
     
    PURPOSE: This study aimed to investigate the prognostic impact of metabolic heterogeneity (MH) in patients with multiple myeloma (MM). PATIENTS AND METHODS: We retrospectively analyzed MH with 18F-FDG PET/CT in 203 patients with newly diagnosed MM. Metabolic heterogeneity was estimated using the area under the curve of the cumulative SUV volume histogram. To evaluate MH, we selected 2 lesions: "MH-SUVmax," a lesion with SUVmax, and "MH-metabolic tumor volume (MTV)," a lesion with the largest MTV. RESULTS: Metabolic heterogeneity from an MH-SUVmax lesion showed more prognostic relevance than that from a lesion with the largest MTV. The progression-free survival (PFS) and overall survival (OS) rates were significantly lower in the high-MH-SUVmax group than in the low-MH-SUVmax group (median PFS: 25.2 vs 33.9 months; median OS: 41.6 vs 112.0 months; P = 0.004 and 0.046, respectively), whereas high MH-SUVmax retained independent prognostic power on multivariate analysis. Even among patients with high whole-body MTV, those with high MH-SUVmax tended to show poorer prognosis than those without (median PFS, 23.8 vs 30.2 months; P = 0.085). Moreover, patients with high MH-SUVmax and high-risk cytogenetic abnormalities showed dismal outcomes even with standard treatment (median PFS and OS, 10.0 and 33.3 months, respectively). CONCLUSIONS: Our results suggested that high MH-SUVmax based on pretreatment with 18F-FDG PET/CT is a novel prognostic factor for cases of MM.
  • Hayato Kaida, Kazuhiro Kitajima, Masatoyo Nakajo, Mana Ishibashi, Tomoyuki Matsunaga, Ryogo Minamimoto, Kenji Hirata, Koya Nakatani, Ao Hung, Satoshi Hattori, Takushi Yasuda, Kazunari Ishii
    European journal of nuclear medicine and molecular imaging 48 (11) 3666 - 3682 2021/10 [Refereed]
     
    PURPOSE: To investigate the usefulness of the positron emission tomography response criteria in solid tumors 1.0 (PERCIST1.0) for predicting tumor response to neoadjuvant chemotherapy and prognosis and determine whether PERCIST improvements are necessary for esophageal squamous cell carcinoma (ESCC) patients. PATIENTS AND METHODS: We analyzed the cases of 177 ESCC patients and examined the association between PERCIST and their pathological responses. Associations of whole-PERCIST with progression-free survival (PFS) and overall survival (OS) were evaluated by a Kaplan-Meier analysis and Cox proportional hazards model. To investigate potential PERCIST improvements, we used the survival tree technique to understand patients' prognoses. RESULTS: There were significant correlations between the pathologic response and PERCIST of primary tumor (p < 0.001). The optimal cutoff value of the primary tumors' SULpeak response to classify pathologic responses was -50.0%. The diagnostic accuracy of SULpeak response was 87.3% sensitivity, 54.1% specificity, 68.9% accuracy, positive predictive value 60.5%, and negative predictive value 84.1%. Whole-PERCIST was significantly associated with PFS and OS. The survival tree results indicated that a high reduction of the whole SULpeak response was significantly correlated with the patients' prognoses. The cutoff values for the separation of prognoses were - 52.5 for PFS and - 47.1% for OS. CONCLUSION: PERCIST1.0 can help predict tumor responses and prognoses. However, 18F-FDG-PET/CT tends to underestimate residual tumors in histopathological response evaluations. Modified PERCIST, in which the partial metabolic response is further classified by the SULpeak response (-50%), might be more appropriate than PERCIST1.0 for evaluating tumor responses and stratifying high-risk patients for recurrence and poor prognosis.
  • Shigeru Yamaguchi, Kenji Hirata, Michinari Okamoto, Eku Shimosegawa, Jun Hatazawa, Ryuichi Hirayama, Naoki Kagawa, Haruhiko Kishima, Noboru Oriuchi, Masazumi Fujii, Kentaro Kobayashi, Hiroyuki Kobayashi, Shunsuke Terasaka, Ken-Ichi Nishijima, Yuji Kuge, Yoichi M Ito, Hiroshi Nishihara, Nagara Tamaki, Tohru Shiga
    Cancer science 112 (10) 4246 - 4256 2021/10 [Refereed][Not invited]
     
    We conducted a prospective multicenter trial to compare the usefulness of 11 C-methionine (MET) and 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for identifying tumor recurrence. Patients with clinically suspected tumor recurrence after radiotherapy underwent both 11 C-MET and 18 F-FDG PET. When a lesion showed a visually detected uptake of either tracer, it was surgically resected for histopathological analysis. Patients with a lesion negative to both tracers were revaluated by magnetic resonance imaging (MRI) at 3 months after the PET studies. The primary outcome measure was the sensitivity of each tracer in cases with histopathologically confirmed recurrence, as determined by the McNemar test. Sixty-one cases were enrolled, and 56 cases could be evaluated. The 38 cases where the lesions showed uptake of either 11 C-MET or 18 F-FDG underwent surgery; 32 of these cases were confirmed to be subject to recurrence. Eighteen cases where the lesions showed uptake of neither tracer received follow-up MRI; the lesion size increased in one of these cases. Among the cases with histologically confirmed recurrence, the sensitivities of 11 C-MET PET and 18 F-FDG PET were 0.97 (32/33, 95% confidence interval [CI]: 0.85-0.99) and 0.48 (16/33, 95% CI: 0.33-0.65), respectively, and the difference was statistically significant (P < .0001). The diagnostic accuracy of 11 C-MET PET was significantly better than that of 18 F-FDG PET (87.5% vs. 69.6%, P = .033). No examination-related adverse events were observed. The results of the study demonstrated that 11 C-MET PET was superior to 18 F-FDG PET for discriminating between tumor recurrence and radiation-induced necrosis.
  • Katsuki Eguchi, Shinichi Shirai, Masaaki Matsushima, Takahiro Kano, Kazuyoshi Yamazaki, Shuji Hamauchi, Toru Sasamori, Toshitaka Seki, Kenji Hirata, Mayumi Kitagawa, Mika Otsuki, Tohru Shiga, Kiyohiro Houkin, Hidenao Sasaki, Ichiro Yabe
    BMC neurology 21 (1) 351 - 351 2021/09/13 [Refereed][Not invited]
     
    BACKGROUND: Weight gain (WG) is a frequently reported side effect of subthalamic deep brain stimulation; however, the underlying mechanisms remain unclear. The active contact locations influence the clinical outcomes of subthalamic deep brain stimulation, but it is unclear whether WG is directly associated with the active contact locations. We aimed to determine whether WG is associated with the subthalamic deep brain stimulation active contact locations. METHODS: We enrolled 14 patients with Parkinson's disease who underwent bilateral subthalamic deep brain stimulation between 2013 and 2019. Bodyweight and body mass index were measured before and one year following the surgery. The Lead-DBS Matlab toolbox was used to determine the active contact locations based on magnetic resonance imaging and computed tomography. We also created sweet spot maps for WG using voxel-wise statistics, based on volume of tissue activation and the WG of each patient. Fluorodeoxyglucose-positron emission tomography data were also acquired before and one year following surgery, and statistical parametric mapping was used to evaluate changes in brain metabolism. We examined which brain regions' metabolism fluctuation significantly correlated with increased body mass index scores and positron emission tomography data. RESULTS: One year after surgery, the body mass index increase was 2.03 kg/m2. The sweet spots for WG were bilateral, mainly located dorsally outside of the subthalamic nucleus (STN). Furthermore, WG was correlated with increased metabolism in the left limbic and associative regions, including the middle temporal gyrus, inferior frontal gyrus, and orbital gyrus. CONCLUSIONS: Although the mechanisms underlying WG following subthalamic deep brain stimulation are possibly multifactorial, our findings suggest that dorsal stimulation outside of STN may lead to WG. The metabolic changes in limbic and associative cortical regions after STN-DBS may also be one of the mechanisms underlying WG. Further studies are warranted to confirm whether dorsal stimulation outside of STN changes the activities of these cortical regions.
  • Yuta Kobayashi, Takuma Sato, Toshiyuki Nagai, Kenji Hirata, Satonori Tsuneta, Yoshiya Kato, Hirokazu Komoriyama, Kiwamu Kamiya, Takao Konishi, Kazunori Omote, Hiroshi Ohira, Kohsuke Kudo, Satoshi Konno, Toshihisa Anzai
    ESC heart failure 8 (6) 5282 - 5292 2021/09/12 [Refereed][Not invited]
     
    AIMS: Although soluble interleukin 2 receptor (sIL-2R) is a potentially useful biomarker in the diagnosis and evaluation of disease severity in patients with sarcoidosis, its prognostic implication in patients with cardiac sarcoidosis (CS) is unclear. We sought to investigate whether sIL-2R was associated with clinical outcomes and to clarify the relationship between sIL-2R levels and disease activity in patients with CS. METHODS AND RESULTS: We examined 83 consecutive patients with CS in our hospital who had available serum sIL-2R data between May 2003 and February 2020. The primary outcome was a composite of advanced atrioventricular block, ventricular tachycardia or ventricular fibrillation, heart failure hospitalization, and all-cause death. Inflammatory activity in the myocardium and lymph nodes was assessed by 18 F-fluorideoxyglucose positron emission tomography/computed tomography. During a median follow-up period of 2.96 (IQR 2.24-4.27) years, the primary outcome occurred in 24 patients (29%). Higher serum sIL-2R levels (>538 U/mL, the median) were significantly related to increased incidence of primary outcome (P = 0.037). Multivariable Cox regression analysis showed that a higher sIL-2R was independently associated with an increased subsequent risk of adverse events (HR 3.71, 95% CI 1.63-8.44, P = 0.002), even after adjustment for significant covariates. sIL-2R levels were significantly correlated to inflammatory activity in lymph nodes (r = 0.346, P = 0.003) but not the myocardium (r = 0.131, P = 0.27). CONCLUSIONS: Increased sIL-2R is associated with worse long-term clinical outcomes accompanied by increased systemic inflammatory activity in CS patients.
  • Yuko Uchiyama, Kenji Hirata, Shiro Watanabe, Shozo Okamoto, Tohru Shiga, Kazufumi Okada, Yoichi M Ito, Kohsuke Kudo
    Annals of nuclear medicine 35 (11) 1223 - 1231 2021/08/11 [Refereed][Not invited]
     
    BACKGROUND: Although patients with differentiated thyroid cancer (DTC) generally have a good prognosis, patients with a large metabolic tumor volume (MTV) on FDG-PET may experience poor clinical courses. We measured organ-based MTVs and tested its prognostic performance in comparison to conventional MTV (cMTV). METHODS: We retrospectively analyzed the cases of 280 patients who received their first I-131 therapy in 2003-2014 at our hospital and showed an FDG-avid metastatic lesion. We randomly divided the patients into training (n = 190) and validation (n = 90) datasets. We classified the MTVs as MTVneck-node, MTVdistant-node, MTVlung, MTVbone, and MTVother-organs and tested with/without dichotomization vis-à-vis overall survival (OS). Based on the estimated weighting coefficients of the organ-based MTVs, we propose a new index: the adjusted whole-body MTV (aMTV). Using the validation dataset, we compared the aMTV with cMTV for predicting OS. RESULTS: In a univariate analysis, MTVdistant-node and MTVother-organs were more strongly correlated with the OS than the dichotomized forms, whereas the dichotomized forms of MTVneck-node, MTVlung, and MTVbone were more strongly correlated with OS than the continuous variables. The aMTV was thus expressed as 0.69 × dic(MTVneck-node) + 0.02 × MTVdistant-node + 1.05 × dic(MTVlung) + 1.58 × dic(MTVbone) + 0.01 × MTVother-organs, where dic(x) represents 0 or 1 based on the optimized cut-off. In the model evaluation using the validation group, aMTV was a significant predictor of OS with a higher c-index (0.7676) than cMTV (0.7218). CONCLUSION: In DTC patients with FDG-avid metastasis before I-131 therapy, all organ-based MTVs were significant predictors of prognosis. As the aMTV outperformed the cMTV for predicting prognoses, we recommend measuring the MTV on an organ basis.
  • Noriyuki Fujima, V Carlota Andreu-Arasa, Sara K Meibom, Gustavo A Mercier, Minh Tam Truong, Kenji Hirata, Koichi Yasuda, Satoshi Kano, Akihiro Homma, Kohsuke Kudo, Osamu Sakai
    BMC cancer 21 (1) 900 - 900 2021/08/06 [Refereed][Not invited]
     
    BACKGROUND: This study aimed to assess the utility of deep learning analysis using pretreatment FDG-PET images to predict local treatment outcome in oropharyngeal squamous cell carcinoma (OPSCC) patients. METHODS: One hundred fifty-four OPSCC patients who received pretreatment FDG-PET were included and divided into training (n = 102) and test (n = 52) sets. The diagnosis of local failure and local progression-free survival (PFS) rates were obtained from patient medical records. In deep learning analyses, axial and coronal images were assessed by three different architectures (AlexNet, GoogLeNET, and ResNet). In the training set, FDG-PET images were analyzed after the data augmentation process for the diagnostic model creation. A multivariate clinical model was also created using a binomial logistic regression model from a patient's clinical characteristics. The test data set was subsequently analyzed for confirmation of diagnostic accuracy. Assessment of local PFS rates was also performed. RESULTS: Training sessions were successfully performed with an accuracy of 74-89%. ROC curve analyses revealed an AUC of 0.61-0.85 by the deep learning model in the test set, whereas it was 0.62 by T-stage, 0.59 by clinical stage, and 0.74 by a multivariate clinical model. The highest AUC (0.85) was obtained with deep learning analysis of ResNet architecture. Cox proportional hazards regression analysis revealed deep learning-based classification by a multivariate clinical model (P < .05), and ResNet (P < .001) was a significant predictor of the treatment outcome. In the Kaplan-Meier analysis, the deep learning-based classification divided the patient's local PFS rate better than the T-stage, clinical stage, and a multivariate clinical model. CONCLUSIONS: Deep learning-based diagnostic model with FDG-PET images indicated its possibility to predict local treatment outcomes in OPSCCs.
  • Yutaka Hoshino, Minako Sugiyama, Kenji Hirata, Shohei Honda, Hitoshi Saito, Atsushi Manabe, Kohsuke Kudo
    Acta radiologica open 10 (7) 20584601211026810 - 20584601211026810 2021/07 [Refereed][Not invited]
     
    Commonly, physiological 18F-fluorodeoxyglucose (FDG) uptake in the brain can be observed in 18F-FDG positron emission tomography. Abnormal uptake of 18F-FDG in the brain suggests disorders of central nervous system. Here, we present a case of extremely low 18F-FDG uptake in the brain of a 4-year-old girl with whole-body metastatic neuroblastoma. Almost missing of physiological 18F-FDG uptake in the brain was ascribed at least partly to the metastatic neuroblastoma. The brain could regain physiological 18F-FDG uptake after chemotherapy.
  • Takehiro Noji, Ayano Inoue, Yoshitsugu Nakanishi, Takahiro Tsuchikawa, Keisuke Okamura, Kenji Hirata, Satoshi Hirano
    Journal of gastrointestinal surgery : official journal of the Society for Surgery of the Alimentary Tract 25 (12) 3236 - 3238 2021/06/25 [Refereed][Not invited]
  • Yoko Satoh, Masamichi Imai, Kenji Hirata, Yuzo Asakawa, Chihiro Ikegawa, Hiroshi Onishi
    Annals of nuclear medicine 35 (5) 608 - 616 2021/03/27 [Refereed]
     
    OBJECTIVE: This study aimed to determine the optimal β value of the relaxation control parameter and the post-smoothing filter in the list-mode dynamic row-action maximum likelihood algorithm (LM-DRAMA) to detect early stage breast cancer with high-resolution dedicated breast positron emission tomography (dbPET) in phantom and clinical studies. METHODS: A breast phantom containing four spheres (5, 7.5, 10, and 16 mm in diameter) was filled with 18F-fluorodeoxyglucose solution (sphere-to-background ratio, 8:1) and scanned on a dbPET scanner. The images were reconstructed using LM-DRAMA with different β values (5, 20, or 100) and Gaussian post-filters (0, 0.78, 1.17, 1.56, 1.95, or 2.34 mm). Other conditions were according to those routinely used (1 iteration and 128 subsets including attenuation and scatter correction). Image quality was evaluated visually and by computing the coefficient of variation of the background (CVBG), detectability index (DI), and contrast recovery coefficient. Parameters optimized in these phantom studies were applied to 25 clinical data sets. Variabilities for different reconstruction methods in visual scores, the maximum standardized uptake value of breast cancer, and the tumor-to-background uptake ratio were estimated. RESULTS: The reconstruction images of the phantom with higher β values and smaller post-filters yielded higher visual scores for detectability and DI and lower smoothness and CVBG scores. Based on the phantom study, the β values and post-filter were optimized for clinical dbPET images except for β5 and 2.34 mm post-filter. Applying the other reconstructions to clinical studies showed that β100 provided higher quantitative parameter values. The detectability of lesions was similar for β100 and β20 and decreased with larger post-filters. The lesion detection rate was similar for β100 and β20 and decreased with larger post-filter. CONCLUSION: The relaxation coefficient factor β20 and a 0.78- or 1.17-mm post-filter were optimal for dbPET image reconstruction with balanced spatial resolution and noise. However, they should be selected according to the impact on the dbPET image and the purpose of the examination.
  • Kenji Hirata, Nagara Tamaki
    Cancers 13 (4) 2021/02/19 [Refereed]
     
    Positron emission tomography (PET) has unique characteristics for quantitative assessment of tumour biology in vivo. Accumulation of F-18 fluorodeoxyglucose (FDG) may reflect tumour characteristics based on its metabolic activity. Quantitative assessment of FDG uptake can often be applied for treatment monitoring after chemotherapy or chemoradiotherapy. Numerous studies indicated biochemical change assessed by FDG PET as a more sensitive marker than morphological change estimated by CT or MRI. In addition, those with complete metabolic response after therapy may show better disease-free survival and overall survival than those with other responses. Assessment of metabolic change may be performed using absolute FDG uptake in the tumour (standardized uptake value: SUV). In addition, volumetric parameters such as metabolic tumour volume (MTV) have been introduced for quantitative assessment of FDG uptake in tumour. More recently, radiomics approaches that focus on image-based precision medicine have been applied to FDG PET, as well as other radiological imaging. Among these, texture analysis extracts intratumoral heterogeneity on a voxel-by-voxel basis. Combined with various machine learning techniques, these new quantitative parameters hold a promise for assessing tissue characterization and predicting treatment effect, and could also be used for future prognosis of various tumours, although multicentre clinical trials are needed before application in clinical settings.
  • Osamu Manabe, Shigeru Yamaguchi, Kenji Hirata, Kentaro Kobayashi, Hiroyuki Kobayashi, Shunsuke Terasaka, Takuya Toyonaga, Keiichi Magota, Yuji Kuge, Nagara Tamaki, Tohru Shiga, Kohsuke Kudo
    Diagnostics (Basel, Switzerland) 11 (2) 2021/01/28 [Refereed]
     
    BACKGROUND: Positron emission tomography with 11C-methionine (MET) is well established in the diagnostic work-up of malignant brain tumors. Texture analysis is a novel technique for extracting information regarding relationships among surrounding voxels, in order to quantify their inhomogeneity. This study evaluated whether the texture analysis of MET uptake has prognostic value for patients with glioma. METHODS: We retrospectively analyzed adults with glioma who had undergone preoperative metabolic imaging at a single center. Tumors were delineated using a threshold of 1.3-fold of the mean standardized uptake value for the contralateral cortex, and then processed to calculate the texture features in glioma. RESULTS: The study included 42 patients (median age: 56 years). The World Health Organization classifications were grade II (7 patients), grade III (17 patients), and grade IV (18 patients). Sixteen (16.1%) all-cause deaths were recorded during the median follow-up of 18.8 months. The univariate analyses revealed that overall survival (OS) was associated with age (hazard ratio (HR) 1.04, 95% confidence interval (CI) 1.01-1.08, p = 0.0093), tumor grade (HR 3.64, 95% CI 1.63-9.63, p = 0.0010), genetic status (p < 0.0001), low gray-level run emphasis (LGRE, calculated from the gray-level run-length matrix) (HR 2.30 × 1011, 95% CI 737.11-4.23 × 1019, p = 0.0096), and correlation (calculated from the gray-level co-occurrence matrix) (HR 5.17, 95% CI 1.07-20.93, p = 0.041). The multivariate analyses revealed OS was independently associated with LGRE and correlation. The survival curves were also significantly different (both log-rank p < 0.05). CONCLUSION: Textural features obtained using preoperative MET positron emission tomography may compliment the semi-quantitative assessment for prognostication in glioma cases.
  • Zongyao Li, Kazuhiro Kitajima, Kenji Hirata, Ren Togo, Junki Takenaka, Yasuo Miyoshi, Kohsuke Kudo, Takahiro Ogawa, Miki Haseyama
    EJNMMI research 11 (1) 10 - 10 2021/01/25 [Refereed]
     
    BACKGROUND: To improve the diagnostic accuracy of axillary lymph node (LN) metastasis in breast cancer patients using 2-[18F]FDG-PET/CT, we constructed an artificial intelligence (AI)-assisted diagnosis system that uses deep-learning technologies. MATERIALS AND METHODS: Two clinicians and the new AI system retrospectively analyzed and diagnosed 414 axillae of 407 patients with biopsy-proven breast cancer who had undergone 2-[18F]FDG-PET/CT before a mastectomy or breast-conserving surgery with a sentinel lymph node (LN) biopsy and/or axillary LN dissection. We designed and trained a deep 3D convolutional neural network (CNN) as the AI model. The diagnoses from the clinicians were blended with the diagnoses from the AI model to improve the diagnostic accuracy. RESULTS: Although the AI model did not outperform the clinicians, the diagnostic accuracies of the clinicians were considerably improved by collaborating with the AI model: the two clinicians' sensitivities of 59.8% and 57.4% increased to 68.6% and 64.2%, respectively, whereas the clinicians' specificities of 99.0% and 99.5% remained unchanged. CONCLUSIONS: It is expected that AI using deep-learning technologies will be useful in diagnosing axillary LN metastasis using 2-[18F]FDG-PET/CT. Even if the diagnostic performance of AI is not better than that of clinicians, taking AI diagnoses into consideration may positively impact the overall diagnostic accuracy.
  • Satonori Tsuneta, Noriko Oyama-Manabe, Kenji Hirata, Taisuke Harada, Tadao Aikawa, Osamu Manabe, Hiroshi Ohira, Kazuhiro Koyanagawa, Masanao Naya, Kohsuke Kudo
    Japanese journal of radiology 39 (5) 442 - 450 2021/01/22 [Refereed]
     
    PURPOSE: To investigate the diagnostic value of texture analysis to differentiate cardiac sarcoidosis (CS) from other non-ischemic cardiomyopathies (non-CS). MATERIALS AND METHODS: Twenty CS patients and 15 non-CS patients who had undergone myocardial CT delayed enhancement (CTDE) were included. A total of 36 texture features were calculated according to the CT attenuation of CTDE. We investigated the diagnostic value to differentiate CS from non-CS. We also assessed the intra- and inter-rater reproducibility for each feature and inter-observer agreement for visual assessment. RESULTS: Seven extracted features had significantly higher run length non-uniformity (RLNU) values (5.4 × 102 ± 6.2 × 102 vs. 11.2 × 102 ± 4.9 × 102, p = 0.037) and significantly lower low gray-level zone emphasis (LGZE) values (7.1 × 10-3 ± 8.6 × 10-3 vs. 18.1 × 10-3 ± 16.9 × 10-3, p = 0.017) in CS than in non-CS. Intra- and inter-rater reproducibility of RLNU and LGZE were excellent (ICCs > 0.8), while inter-observer agreement of visual assessment was poor (kappa = 0.19). The accuracies of texture analysis were 69% with RLNU and 71% with LGZE, which were better than that of visual assessment. CONCLUSION: Texture analysis of CTDE could differentiate CS from non-CS with high reproducibility.
  • Kenji Hirata, Osamu Manabe, Keiichi Magota, Sho Furuya, Tohru Shiga, Kohsuke Kudo
    Frontiers in medicine 8 647562 - 647562 2021 [Refereed][Not invited]
     
    Background: Diagnostic reports contribute not only to the particular patient, but also to constructing massive training dataset in the era of artificial intelligence (AI). The maximum standardized uptake value (SUVmax) is often described in daily diagnostic reports of [18F] fluorodeoxyglucose (FDG) positron emission tomography (PET) - computed tomography (CT). If SUVmax can be used as an identifier of lesion, that would greatly help AI interpret diagnostic reports. We aimed to clarify whether the lesion can be localized using SUVmax strings. Methods: The institutional review board approved this retrospective study. We investigated a total of 112 lesions from 30 FDG PET-CT images acquired with 3 different scanners. SUVmax was calculated from DICOM files based on the latest Quantitative Imaging Biomarkers Alliance (QIBA) publication. The voxels showing the given SUVmax were exhaustively searched in the whole-body images and counted. SUVmax was provided with 5 different degrees of precision: integer (e.g., 3), 1st decimal places (DP) (3.1), 2nd DP (3.14), 3rd DP (3.142), and 4th DP (3.1416). For instance, when SUVmax = 3.14 was given, the voxels with 3.135 ≤ SUVmax < 3.145 were extracted. We also evaluated whether local maximum restriction could improve the identifying performance, where only the voxels showing the highest intensity within some neighborhood were considered. We defined that "identical detection" was achieved when only single voxel satisfied the criterion. Results: A total of 112 lesions from 30 FDG PET-CT images were investigated. SUVmax ranged from 1.3 to 49.1 (median = 5.6). Generally, when larger and more precise SUVmax values were given, fewer voxels satisfied the criterion. The local maximum restriction was very effective. When SUVmax was determined to 4 decimal places (e.g., 3.1416) and the local maximum restriction was applied, identical detection was achieved in 33.3% (lesions with SUVmax < 2), 79.5% (2 ≤ SUVmax < 5), and 97.8% (5 ≤ SUVmax) of lesions. Conclusion: In this preliminary study, SUVmax of FDG PET-CT could be used as an identifier to localize the lesion if precise SUVmax is provided and local maximum restriction was applied, although the lesions showing SUVmax < 2 were difficult to identify. The proposed method may have potential to make use of diagnostic reports retrospectively for constructing training datasets for AI.
  • Kazutaka Harashima, Shiro Watanabe, Nanase Okazaki, Daisuke Endo, Yuko Uchiyama, Fumi Kato, Kenji Hirata, Kohsuke Kudo
    Asia Oceania journal of nuclear medicine & biology 9 (2) 183 - 187 2021 [Refereed][Not invited]
     
    Although 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) is an established method for the staging of malignancies, benign lesions (e.g, active inflammatory lesions) often show increased metabolic activity. Herpes zoster is the clinical manifestation of the activation and replication of dormant varicella-zoster virus (VZV) in individuals with decreased cell-mediated immunity. Although the diagnosis of herpes zoster is clinical, it is sometimes observed incidentally during imaging for another disease. We describe the case of a 67-year-old Japanese female patient diagnosed with cervical cancer in whom FDG-PET/CT revealed herpes zoster manifestations: hypermetabolic cutaneous lesions in the buttock and pelvic lymph node involvement. The resected lymph nodes showed no malignant lesions but revealed lymphoid follicle formation, probably related to viral infection. There has been no report comparing FDG-PET findings of lymph nodes with histologic findings; the present findings are compatible with a clinically VZV-induced inflammatory reaction in regional lymph nodes, which increased FDG accumulation. Active infection with VZV displays increased FDG uptake in regional lymph nodes and may lead to incorrect malignant disease management in oncology. Misdiagnoses can be avoided by a careful interpretation by experienced nuclear medicine physicians as well as proper clinical evaluation.
  • Keiichi Magota, Naoto Numata, Daiki Shinyama, Junya Katahata, Yamato Munakata, Piotr J Maniawski, Kentaro Kobayashi, Osamu Manabe, Kenji Hirata, Ukihide Tateishi, Kohsuke Kudo, Tohru Shiga
    EJNMMI physics 7 (1) 66 - 66 2020/11/13 [Refereed]
     
    BACKGROUND: Halo artifacts from urinary catheters can occur due to inaccurate scatter correction, and the artifacts affect the tumor visibility in 18F-FDG PET/CT images. We investigated the incidence rate and the mechanisms of halo-artifact generation and explored several scatter correction techniques to prevent artifacts. METHODS: We conducted patient and phantom studies. (1) We retrospectively reviewed the cases of patients who had undergone 18F-FDG PET/CT scans. To determine the frequency of halo-artifact generation, we used the patients' PET images with a standard scatter correction based on a tail-fitted single-scatter simulation (TF-SSS) using 4-mm voxel μ-maps (TFS 4-mm). (2) We performed phantom studies to evaluate the effects of a urine catheter and two scatter correction techniques, i.e., TF-SSS with 2-mm voxel μ-maps (TFS 2-mm) and a Monte Carlo-based single-scatter simulation (MC-SSS) using 4-mm voxel μ-maps (MCS 4-mm). The average standardized uptake values (SUVs) were measured for axial PET images. (3) Using the patients' data, we investigated whether TFS 2-mm and MCS 4-mm can eliminate the artifacts in the clinical images. RESULTS: (1) There were 61 patients with urinary catheters; in five (8.2%), halo artifacts were observed in the TFS 4-mm PET images. (2) The phantom study clearly reproduced the halo artifacts in the TFS 4-mm PET images. The halo artifacts were generated when urine moved in the interval between the CT and PET imaging, and when the urinary catheter was placed in a circular shape. The SUVs for the TFS 4-mm and TFS-2mm PET images were underestimated at the halo-artifact regions, whereas the SUVs for the MCS 4-mm PET images were close to the true values. (3) The halo artifacts disappeared in the TFS 2-mm PET images in 4/5 patients but not 1/5 patient, whereas the halo artifacts were completely absent in the MCS 4-mm PET images in 5/5 patients. CONCLUSIONS: These data suggest that halo artifacts are caused if the PET images do not correspond to the physical material in the μ-maps, which induces the scatter correction error. With the MC-SSS, it was possible to accurately estimate the scatter without generating halo artifacts.
  • Hironobu Hata, Tomoka Kitao, Jun Sato, Takuya Asaka, Kenji Imamachi, Masaaki Miyakoshi, Kenji Hirata, Keiichi Magota, Yamato Munakata, Tohru Shiga, Yutaka Yamazaki, Yoshimasa Kitagawa
    Scientific reports 10 (1) 17461 - 17461 2020/10/15 [Refereed]
     
    Effects of long-term bisphosphonate (BP) administration on the metabolism of healthy bone and the concomitant changes in imaging are unclear. Hence, we aimed to retrospectively investigate the effects of long-term BP administration on the intact parietal bone using the standardised uptake value (SUV) derived from single photon emission computed tomography (SPECT). We enrolled 29 patients who had odontogenic infection, osteoporosis, bone metastasis cancer, or rheumatoid arthritis, and classified them into BP-naïve: A (14 patients) and BP-treated: B, < 4 years (7 patients) and C, ≥ 4 years (8 patients) groups. We measured the maximum bilateral SUV (SUVmax) of the parietal bone using quantitative bone SPECT software. There were significant differences in the duration of BP administration and SUVmax of the parietal bone among the diseases (P < 0.0001 and P = 0.0086, respectively). There was a positive correlation between the duration of BP administration and SUVmax of the parietal bone (rs = 0.65, P = 0.0002). The SUVmax was significantly different between A and B (P = 0.02) and between A and C (P = 0.0024) groups. This is the first report on the correlation between long-term BP administration and the SUVmax of the parietal bone using the quantitative bone SPECT analysis.
  • 食道癌の術前化学療法に対するFDG-PET/CTの有用性 多施設共同研究
    甲斐田 勇人, 北島 一宏, 中條 正豊, 石橋 愛, 南本 亮吾, 平田 健司, 中谷 航也, Ao Hung, 服部 聡, 安田 卓司, 石井 一成
    核医学 (一社)日本核医学会 57 (Suppl.) S144 - S144 0022-7854 2020/10
  • 真鍋 治, 小梁川 和宏, 納谷 昌直, 相川 忠夫, 平田 健司, 小林 健太郎, 古家 翔, 真鍋 徳子, 立石 宇貴秀
    臨床放射線 金原出版(株) 65 (8) 825 - 830 0009-9252 2020/08
  • Shiro Watanabe, Ken-Ichi Nishijima, Shozo Okamoto, Keiichi Magota, Kenji Hirata, Takuya Toyonaga, Tohru Shiga, Yuji Kuge, Nagara Tamaki
    Annals of nuclear medicine 34 (8) 595 - 599 2020/08 [Refereed][Not invited]
     
    OBJECTIVE: We evaluated the radiation dosage, biodistribution, human safety, and tolerability of the injection of a single dose of [123I] 5-iodo-6-[(2-iminoimidazolidinyl)methyl]uracil (IIMU), a new radiotracer targeting thymidine phosphorylase (TP), in healthy volunteers. METHODS: Potential participants were tested at our hospital to confirm their eligibility. Two healthy male adults passed the screening tests. They were injected with 56 and 111 MBq of [123I]IIMU, respectively. Safety assessments were performed before and at 1, 3, 6, 9, 24, 48 h, and 1-week post-injection. Whole-body emission scans were conducted at 1, 3, 6, 24, and 48 h post-injection. Regions of interest were manually drawn to enclose the entire body at each time point, identifying high-uptake organs to obtain the time-activity curves. Urine and blood samples were collected at 1, 2, 3, 4, 5, 6, 9, 24, and 48 h post-injection. The radiation dose for each organ and the effective doses were estimated using OLINDA/EXM 1.1 software. RESULTS: No adverse events were observed as of the follow-up visit > 1-week post-injection. In both subjects, the highest uptake of [123I]IIMU occurred in the liver, with peak injected activity (%IA) values of 17.7% and 15.1%, respectively. The second highest uptake was in the thyroid (0.35% and 0.66% IA). The %IA decreased gradually toward the end of the study (48 h) in all organs except the liver and thyroid. By the end of the study, 52.5% and 51.5% of the injected activity of [123I]IIMU had been excreted via the subjects' renal systems. The estimated mean effective doses of [123I]IIMU were 9.19 μSv/MBq and 10.1 μSv/MBq, respectively. CONCLUSION: In this preliminary study, [123I]IIMU was safely administered to healthy adults, and its potential clinical use in TP imaging was revealed.
  • Hironobu Hata, Tomoka Kitao, Jun Sato, Takuya Asaka, Noritaka Ohga, Kenji Imamachi, Kenji Hirata, Tohru Shiga, Yutaka Yamazaki, Yoshimasa Kitagawa
    Scientific reports 10 (1) 11385 - 11385 2020/07/09 [Refereed]
     
    Development of quantitative analysis software has enabled application of several standardised uptake values (SUV) for bone analysis in single photon emission computed tomography (SPECT). The present retrospective study aimed to develop a reliable method of monitoring bone inflammatory activity in antiresorptive agent-related osteonecrosis of the jaw (ARONJ) using SPECT quantitative analysis software. Fifteen ARONJ patients underwent SPECT before and after anti-inflammatory therapy. We calculated the mean maximum SUV (SUVmax) of the bilateral cranial bones using quantitative analysis software and used this as the control [C]. We attempted to adjust the SUVmax of the lesion [L] as follows: adjusted SUVmax (aSUVmax) = [L] - [C]. The optimum threshold to calculate the metabolic bone volume (MBV) (cm3) was [C] + 3. The threshold values obtained for each case were input to calculate MBV at each osteomyelitis site. Retrospectively, we compared aSUVmax and MBV of each patient's ARONJ before and after anti-inflammatory therapy. The patients' high aSUVmax or large MBV of the ARONJ reduced rapidly, reflecting individual clinical findings after treatment. Application of SPECT quantitative analysis software to monitor bone inflammatory activity in ARONJ could improve the prognosis-deciding abilities of clinicians and enable them to treat ARONJ effectively.
  • Hajime Senjo, Kenji Hirata, Koh Izumiyama, Koichiro Minauchi, Eriko Tsukamoto, Kazuo Itoh, Minoru Kanaya, Akio Mori, Shuichi Ota, Daigo Hashimoto, Takanori Teshima
    Blood advances 4 (10) 2286 - 2296 2020/05/26 [Refereed]
     
    Metabolic heterogeneity (MH) can be measured using 18F-fluorodeoxyglucose (18FDG) positron emission tomography/computed tomography (PET/CT), and it indicates an inhomogeneous tumor microenvironment. High MH has been shown to predict a worse prognosis for primary mediastinal B-cell lymphoma, whereas its prognostic value in diffuse large B-cell lymphoma (DLBCL) remains to be determined. In the current study, we investigated the prognostic values of MH evaluated in newly diagnosed DLBCL. In the training cohort, 86 patients treated with cyclophosphamide, doxorubicin, vincristine, and prednisone-like chemotherapies were divided into low-MH and high-MH groups using receiver operating characteristic analysis. MH was not correlated with metabolic tumor volume of the corresponding lesion, indicating that MH was independent of tumor burden. At 5 years, overall survivals were 89.5% vs 61.2% (P = .0122) and event-free survivals were 73.1% vs 51.1% (P = .0327) in the low- and high-MH groups, respectively. A multivariate Cox-regression analysis showed that MH was an independent predictive factor for overall survival. The adverse prognostic impacts of high MH were confirmed in an independent validation cohort with 64 patients. In conclusion, MH on baseline 18FDG-PET/CT scan predicts treatment outcomes for patients with newly diagnosed DLBCL.
  • T Shima, N Fujima, S Yamano, K Kudo, K Hirata, K Minowa
    Clinical radiology 75 (5) 397.e15-397.e21  2020/05 [Refereed][Not invited]
     
    AIM: To evaluate and compare diffusion-weighted imaging (DWI) parameters derived from a non-Gaussian fitting model and positron-emission tomography (PET) parameters derived from 18F-fluoromisonidazole-PET (FMISO-PET) in patients with oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: Primary sites were evaluated prospectively in 18 patients. DWI was performed using six b-values (0-2,500). Diffusion-related parameters of kurtosis value (K), the kurtosis-corrected diffusion coefficient (DK), diffusion heterogeneity (α), distributed diffusion coefficient (DDC), the slow diffusion coefficient (Dslow), and the apparent diffusion coefficient (ADC) were calculated from four diffusion-fitting models. Maximal standardised uptake values (SUVmax), mean standardised uptake values (SUVmean), and the tumour-to-muscle ration (TMR) of the SUV value were calculated for FMISO-PET. Spearman's correlation coefficient was used to evaluate the correlation between each non-Gaussian diffusion model parameters and PET parameter. RESULTS: There was moderate correlation between FMISO-PET SUVmax and Dslow (ρ=-0.45, p=0.06). In addition, there was good correlation between TMRmax and five non-Gaussian diffusion model parameters (K: ρ=0.65, p=0.004, DK: ρ=-0.72, p=0.0008, DDC: ρ=-0.75, p=0.0003, ADC: ρ=-0.74, p=0.0005, and Dslow: ρ= -0.65, p=0.003), and between TMRmean and five non-Gaussian model parameters (K: ρ=0.64, p=0.005, DK: ρ=-0.61, p=0.007, DDC: ρ=-0.63, p=0.005, ADC: ρ=-0.61, p=0.007, and Dslow: ρ=-0.56, p=0.015). CONCLUSION: Non-Gaussian diffusion model parameters can be related to tumour hypoxia.
  • Osamu Manabe, Kazuhiro Koyanagawa, Kenji Hirata, Noriko Oyama-Manabe, Hiroshi Ohira, Tadao Aikawa, Sho Furuya, Masanao Naya, Ichizo Tsujino, Yuuki Tomiyama, Yuka Otaki, Toshihisa Anzai, Nagara Tamaki
    JACC. Cardiovascular imaging 13 (4) 1096 - 1097 2020/04 [Refereed][Not invited]
  • Keisuke Kawauchi, Sho Furuya, Kenji Hirata, Chietsugu Katoh, Osamu Manabe, Kentaro Kobayashi, Shiro Watanabe, Tohru Shiga
    BMC cancer 20 (1) 227 - 227 2020/03/17 [Refereed]
     
    BACKGROUND: As the number of PET/CT scanners increases and FDG PET/CT becomes a common imaging modality for oncology, the demands for automated detection systems on artificial intelligence (AI) to prevent human oversight and misdiagnosis are rapidly growing. We aimed to develop a convolutional neural network (CNN)-based system that can classify whole-body FDG PET as 1) benign, 2) malignant or 3) equivocal. METHODS: This retrospective study investigated 3485 sequential patients with malignant or suspected malignant disease, who underwent whole-body FDG PET/CT at our institute. All the cases were classified into the 3 categories by a nuclear medicine physician. A residual network (ResNet)-based CNN architecture was built for classifying patients into the 3 categories. In addition, we performed a region-based analysis of CNN (head-and-neck, chest, abdomen, and pelvic region). RESULTS: There were 1280 (37%), 1450 (42%), and 755 (22%) patients classified as benign, malignant and equivocal, respectively. In the patient-based analysis, CNN predicted benign, malignant and equivocal images with 99.4, 99.4, and 87.5% accuracy, respectively. In region-based analysis, the prediction was correct with the probability of 97.3% (head-and-neck), 96.6% (chest), 92.8% (abdomen) and 99.6% (pelvic region), respectively. CONCLUSION: The CNN-based system reliably classified FDG PET images into 3 categories, indicating that it could be helpful for physicians as a double-checking system to prevent oversight and misdiagnosis.
  • Andrew J Surmak, Koon-Pong Wong, Graham B Cole, Kenji Hirata, Alexander A Aabedi, Omid Mirfendereski, Payam Mirfendereski, Amy S Yu, Sung-Cheng Huang, John M Ringman, David S Liebeskind, Jorge R Barrio
    Journal of Alzheimer's disease : JAD 73 (3) 1023 - 1033 2020 [Refereed]
     
    BACKGROUND: 2-(4'- [11C]Methylaminophenyl)-6-hydroxybenzothiazole ([11C]-PiB), purportedly a specific imaging agent for cerebral amyloid-β plaques, is a specific, high affinity substrate for estrogen sulfotransferase (SULT1E1), an enzyme that regulates estrogen homeostasis. OBJECTIVE: In this work, we use positron emission tomography (PET) imaging with [11C]-PiB to assess the functional activity of SULT1E1 in the brain of moyamoya disease patients. METHODS: Ten moyamoya subjects and five control patients were evaluated with [11C]-PiB PET and structural MRI scans. Additionally, a patient with relapsing-remitting multiple sclerosis (RRMS) received [11C]-PiB PET scans before and after steroidal and immunomodulatory therapy. Parametric PET images were established to assess SULT1E1 distribution in the inflamed brain tissue. RESULTS: Increased [11C]-PiB SRTM DVR in the thalamus, pons, corona radiata, and internal capsule of moyamoya cohort subjects was observed in comparison with controls (p ≤ 0.01). This was observed in patients without treatment, with collateralization, and also after radiation. The post-treatment [11C]-PiB PET scan in one RRMS patient also revealed substantially reduced subcortical brain inflammation. In validation studies, [11C]-PiB autoradiography signal in the peri-infarct area of the rat middle cerebral arterial occlusion stroke model was shown to correlate with SULT1E1 immunohistochemistry. CONCLUSION: Strong [11C]-PiB PET signal associated with intracranial inflammation in the moyamoya syndrome cohort and a single RRMS patient appears consistent with functional imaging of SULT1E1 activity in the human brain. This preliminary work offers substantial and direct evidence that significant [11C]-PiB PET focal signals can be obtained from the living human brain with intracranial inflammation, signals not attributable to amyloid-β plaques.
  • Yoko Satoh, Kenji Hirata, Daiki Tamada, Satoshi Funayama, Hiroshi Onishi
    Frontiers in medicine 7 603303 - 603303 2020 [Refereed]
     
    Objective: This retrospective study aimed to compare the ability to classify tumor characteristics of breast cancer (BC) of positron emission tomography (PET)-derived texture features between dedicated breast PET (dbPET) and whole-body PET/computed tomography (CT). Methods: Forty-four BCs scanned by both high-resolution ring-shaped dbPET and whole-body PET/CT were analyzed. The primary BC was extracted with a standardized uptake value (SUV) threshold segmentation method. On both dbPET and PET/CT images, 38 texture features were computed; their ability to classify tumor characteristics such as tumor (T)-category, lymph node (N)-category, molecular subtype, and Ki67 levels was compared. The texture features were evaluated using univariate and multivariate analyses following principal component analysis (PCA). AUC values were used to evaluate the diagnostic power of the computed texture features to classify BC characteristics. Results: Some texture features of dbPET and PET/CT were different between Tis-1 and T2-4 and between Luminal A and other groups, respectively. No association with texture features was found in the N-category or Ki67 level. In contrast, receiver-operating characteristic analysis using texture features' principal components showed that the AUC for classification of any BC characteristics were equally good for both dbPET and whole-body PET/CT. Conclusions: PET-based texture analysis of dbPET and whole-body PET/CT may have equally good classification power for BC.
  • Masashi Kawakami, Kenji Hirata, Sho Furuya, Kentaro Kobayashi, Hiroyuki Sugimori, Keiichi Magota, Chietsugu Katoh
    Frontiers in medicine 7 616746 - 616746 2020 [Refereed]
     
    Deep learning technology is now used for medical imaging. YOLOv2 is an object detection model using deep learning. Here, we applied YOLOv2 to FDG-PET images to detect the physiological uptake on the images. We also investigated the detection precision of abnormal uptake by a combined technique with YOLOv2. Using 3,500 maximum intensity projection (MIP) images of 500 cases of whole-body FDG-PET examinations, we manually drew rectangular regions of interest with the size of each physiological uptake to create a dataset. Using YOLOv2, we performed image training as transfer learning by initial weight. We evaluated YOLOv2's physiological uptake detection by determining the intersection over union (IoU), average precision (AP), mean average precision (mAP), and frames per second (FPS). We also developed a combination method for detecting abnormal uptake by subtracting the YOLOv2-detected physiological uptake. We calculated the coverage rate, false-positive rate, and false-negative rate by comparing the combination method-generated color map with the abnormal findings identified by experienced radiologists. The APs for physiological uptakes were: brain, 0.993; liver, 0.913; and bladder, 0.879. The mAP was 0.831 for all classes with the IoU threshold value 0.5. Each subset's average FPS was 31.60 ± 4.66. The combination method's coverage rate, false-positive rate, and false-negative rate for detecting abnormal uptake were 0.9205 ± 0.0312, 0.3704 ± 0.0213, and 0.1000 ± 0.0774, respectively. The physiological uptake of FDG-PET on MIP images was quickly and precisely detected using YOLOv2. The combination method, which can be utilized the characteristics of the detector by YOLOv2, detected the radiologist-identified abnormalities with a high coverage rate. The detectability and fast response would thus be useful as a diagnostic tool.
  • Sho Furuya, Masanao Naya, Osamu Manabe, Kenji Hirata, Hiroshi Ohira, Tadao Aikawa, Kazuhiro Koyanagawa, Keiichi Magota, Ichizo Tsujino, Toshihisa Anzai, Yuji Kuge, Noriko Oyama-Manabe, Kohsuke Kudo, Tohru Shiga, Nagara Tamaki
    Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology 28 (5) 2141 - 2148 2019/12/09 [Refereed][Not invited]
     
    BACKGROUND: 18F-fluoromisonidazole (FMISO) is a hypoxia positron emission tomography (PET) tracer. Here, we evaluated cardiac and extra-cardiac sarcoidosis using both FMISO and 18F-fluorodeoxyglucose (FDG) PET/CT in a prospective cohort of patients with sarcoidosis. METHODS: Ten consecutive sarcoidosis patients with suspected cardiac involvement were prospectively enrolled. Each patient fasted overnight (for ≥ 18 hours) preceded by a low-carbohydrate diet before FDG PET/CT but not given special dietary instructions before the FMISO PET/CT scan. We visually and semiquantitatively assessed the uptakes of FMISO and FDG using the maximal standardized uptake value (SUVmax). The metabolic volume (MV) of FDG was calculated as the volume within the boundary determined by the threshold (mean SUV of blood pool × 1.5). RESULTS: Nine patients showed focal FDG uptake in the myocardium and were diagnosed with cardiac sarcoidosis. Among the patients with extra-cardiac lesions, FDG uptake was seen in 8 lymph nodes and 3 lung lesions. FMISO uptake was seen in the 7 cardiac (77.8%) and 6 extra-cardiac (54.5%) lesions. None of the patients showed physiological FMISO uptake in the myocardium. The SUVmax values of the lesions with FMISO uptake were higher than those of the lesions without FMISO uptake in both the cardiac (SUVmax: 9.9, IQR: 8.4-10.0 vs 7.3, IQR: 6.3-8.2) and non-cardiac lesions (SUVmax: 17.6, IQR: 14.5-19.3 vs 6.1, IQR: 5.9-6.2; P = 0.006). The MV values of the lesions with FMISO uptake were significantly higher than those of the lesions without FMISO uptake (111.3, IQR: 78.3-135.7 vs 6.4, IQR: 1.9-23.3; P = 0.0009). CONCLUSIONS: FMISO showed no physiological myocardial uptake and did not require special preparation. FMISO PET has the potential to detect hypoxic lesions in patients with sarcoidosis.
  • Shiro Watanabe, Tetsuya Inoue, Shozo Okamoto, Keiichi Magota, Ayumi Takayanagi, Jun Sakakibara-Konishi, Norio Katoh, Kenji Hirata, Osamu Manabe, Takuya Toyonaga, Yuji Kuge, Hiroki Shirato, Nagara Tamaki, Tohru Shiga
    EJNMMI research 9 (1) 104 - 104 2019/12/04 [Refereed][Not invited]
     
    BACKGROUND: We investigated the prognostic predictive value of the combination of fluorodeoxyglucose (FDG)- and fluoromisonidazole (FMISO)-PET in patients with non-small cell lung carcinoma (NSCLC) treated with stereotactic body radiation therapy (SBRT). PATIENTS AND METHODS: We prospectively examined patients with pathologically proven NSCLC; all underwent FDG and FMISO PET/CT scans before SBRT. PET images were acquired using a whole-body time-of-flight PET-CT scanner with respiratory gating. We classified them into recurrent and non-recurrent groups based on their clinical follow-ups and compared the groups' tumor diameters and PET parameters (i.e., maximum of the standardized uptake value (SUVmax), metabolic tumor volume, tumor-to-muscle ratio, and tumor-to-blood ratio). We performed univariate analysis to evaluate the impact of the PET variables on the patients' progression-free survival (PFS). We divided the patients by thresholds of FDG SUVmax and FMISO SUVmax obtained from receiver operating characteristic analysis for assessment of recurrence rate and PFS. RESULTS: Thirty-two NSCLC patients (19 male and 13 females; median age, 83 years) were enrolled. All received SBRT. At the study endpoint, 23 patients (71.9%) were non-recurrent and nine patients (28.1%) had recurrent disease. Significant between-group differences were observed in tumor diameter and all the PET parameters, demonstrating that those were significant predictors of the recurrence in all patients. In the 22 patients with tumors > 2 cm, tumor diameter and FDG SUVmax were not significant predictors. Thirty-two patients were divided into three patterns from the thresholds of FDG SUVmax (6.81) and FMISO SUVmax (1.89); A, low FDG and low FMISO (n = 14); B, high FDG and low FMISO (n = 8); C, high FDG and high FMISO (n = 10). No pattern A patient experienced tumor recurrence, whereas two pattern B patients (25%) and seven pattern C patients (70%) exhibited recurrence. A Kaplan-Meier analysis of all patients revealed a significant difference in PFS between patterns A and B (p = 0.013) and between patterns A and C (p < 0.001). In the tumors > 2 cm patients, significant differences in PFS were demonstrated between pattern A and C patients (p = 0.002). CONCLUSION: The combination of FDG- and FMISO-PET can identify patients with a baseline risk of recurrence and indicate whether additional therapy might be performed to improve survival.
  • Kentaro Kobayashi, Osamu Manabe, Kenji Hirata, Shigeru Yamaguchi, Hiroyuki Kobayashi, Shunsuke Terasaka, Takuya Toyonaga, Sho Furuya, Keiichi Magota, Yuji Kuge, Kohsuke Kudo, Tohru Shiga, Nagara Tamaki
    European journal of nuclear medicine and molecular imaging 47 (8) 1833 - 1842 2019/11/28 [Refereed][Not invited]
     
    PURPOSE: 18F-fluoromisonidazole (18F-FMISO) is the most widely used positron emission tomography (PET) tracer for imaging tumor hypoxia. Previous reports suggested that the time from injection to the scan may affect the assessment of 18F-FMISO uptake. Herein, we directly compared the images at 2 h and 4 h after a single injection of 18F-FMISO. METHODS: Twenty-three patients with or suspected of having a brain tumor were scanned twice at 2 and 4 h following an intravenous injection of 18F-FMISO. We estimated the mean standardized uptake value (SUV) of the gray matter and white matter and the gray-to-white matter ratio in the background brain tissue from the two scans. We also performed a semi-quantitative analysis using the SUVmax and maximum tumor-to-normal ratio (TNR) for the tumor. RESULTS: At 2 h, the SUVmean of gray matter was significantly higher than that of white matter (median 1.23, interquartile range (IQR) 1.10-1.32 vs. 1.04, IQR 0.95-1.16, p < 0.0001), whereas at 4 h, it significantly decreased to approach that of the white matter (1.10, IQR 1.00-1.23 vs. 1.02, IQR 0.93-1.13, p = NS). The gray-to-white matter ratio thus significantly declined from 1.17 (IQR 1.14-1.19) to 1.09 (IQR 1.07-1.10) (p < 0.0001). All 7 patients with glioblastoma showed significant increases in the SUVmax (2.20, IQR 1.67-3.32 at 2 h vs. 2.65, IQR 1.74-4.41 at 4 h, p = 0.016) and the TNR (1.75, IQR 1.40-2.38 at 2 h vs. 2.34, IQR 1.67-3.60 at 4 h, p = 0.016). CONCLUSION: In the assessment of hypoxic tumors, 18F-FMISO PET for hypoxia imaging should be obtained at 4 h rather than 2 h after the injection.
  • Yoshihiro Nishiyama, Seigo Kinuya, Takashi Kato, Daiki Kayano, Shuhei Sato, Manabu Tashiro, Mitsuaki Tatsumi, Teisuke Hashimoto, Shingo Baba, Kenji Hirata, Mana Yoshimura, Hiroto Yoneyama
    Annals of Nuclear Medicine 33 (10) 725 - 732 0914-7187 2019/10 [Refereed][Not invited]
     
    OBJECTIVE: Subcommittee on Survey of Nuclear Medicine Practice in Japan has performed a nationwide survey of nuclear medicine practice every 5 years since 1982 to survey contemporary nuclear medicine practice and its changes over the years. METHODS: The subcommittee sent questionnaires, including the number and category of examinations as well as the kind and dose of the radiopharmaceuticals during the 30 days of June 2017, to all nuclear medicine institutes. The total numbers for the year 2017 were then estimated. RESULTS: A total of 1132 institutes responded to the survey, including 351 PET centers. The recovery rate was 90.6%. The number of gamma cameras installed was 1332 in total, with 7.0% decrease in 5 years. Dual-head cameras and hybrid SPECT/CT scanners accounted for 88.2 and 23.6%, respectively. The number of single-photon tracer studies in 2017 was 1.08 million which means a decrease in 5.7% in 5 years and 23.6% in 10 years. All but neurotransmitter system, sentinel lymph node, and liver scintigraphy decreased. Bone scintigraphy was a leading examination (32.3%), followed by myocardial scintigraphy (24.1%) and cerebral perfusion study (18.0%) in order. SPECT studies showed an increase from 47.2% to 63.5%. PET centers have also increased from 295 to 389, as compared to the last survey. The 112 PET centers have installed one or two in-house cyclotrons. PET studies showed 24.5% increase in 5 years, with oncology accounting for 88.9%. 18F-FDG accounted for 98.2% (630,570 examinations). PET examinations using 11C-methionine have decreased, with 2440 examinations in 2017. PET examinations using 13N-NH3 have been increasing, with 2363 examinations in 2017. The number of PET studies using 11C-PIB was 904. 131I-radioiodine targeted therapies showed an increase in 5 years (23.1%), including 4487 patients for thyroid cancer. Out-patient thyroid bed ablation therapy with 1,110 MBq of 131I accounted for 36.6% of cancer patients. The number of admission rooms increased from 135 to 157 in 5 years. The number of 223Ra targeted therapies for castration-resistant metastatic prostate cancer was 1194 patients. CONCLUSIONS: Single-photon examinations showed a continuous tendency toward a decline in the survey. In contrast, the number of hybrid SPECT/CT scanner examinations has increased. PET/CT study and radionuclide targeted therapy have steadily increased.
  • Hirata K, Yamaguchi S, Shiga T, Kuge Y, Tamaki N
    Journal of clinical medicine 8 (8) 2019/07 [Refereed][Not invited]
     
    Glioma is the most common malignant brain tumor. Hypoxia is closely related to the malignancy of gliomas, and positron emission tomography (PET) can noninvasively visualize the degree and the expansion of hypoxia. Currently, 18F-fluoromisonidazole (FMISO) is the most common radiotracer for hypoxia imaging. The clinical usefulness of FMISO PET has been established; it can distinguish glioblastomas from lower-grade gliomas and can predict the microenvironment of a tumor, including necrosis, vascularization, and permeability. FMISO PET provides prognostic information, including survival and treatment response information. Because hypoxia decreases a tumor's sensitivity to radiation therapy, dose escalation to an FMISO-positive volume is an attractive strategy. Although this idea is not new, an insufficient amount of evidence has been obtained regarding this concept. New tracers for hypoxia imaging such as 18F-DiFA are being tested. In the future, hypoxia imaging will play an important role in glioma management.
  • Watanabe S, Shiga T, Hirata K, Magota K, Okamoto S, Toyonaga T, Higashikawa K, Yasui H, Kobayashi J, Nishijima KI, Iseki K, Matsumoto H, Kuge Y, Tamaki N
    EJNMMI research 9 (1) 60 - 60 2019/07 [Refereed][Not invited]
     
    BACKGROUND: To facilitate hypoxia imaging in a clinical setting, we developed 1-(2,2-dihydroxymethyl-3-[18F]-fluoropropyl)-2-nitroimidazole ([18F]DiFA) as a new tracer that targets tumor hypoxia with its lower lipophilicity and efficient radiosynthesis. Here, we evaluated the radiation dosage, biodistribution, human safety, tolerability, and early elimination after the injection of [18F]DiFA in healthy subjects, and we performed a preliminary clinical study of patients with malignant tumors in a comparison with [18F]fluoromisonidazole ([18F]FMISO). RESULTS: The single administration of [18F]DiFA in 8 healthy male adults caused neither adverse events nor abnormal clinical findings. Dynamic and sequential whole-body scans showed that [18F]DiFA was rapidly cleared from all of the organs via the hepatobiliary and urinary systems. The whole-body mean effective dose of [18F]DiFA estimated by using the medical internal radiation dose (MIRD) schema with organ level internal dose assessment/exponential modeling (OLINDA/EXM) computer software 1.1 was 14.4 ± 0.7 μSv/MBq. Among the organs, the urinary bladder received the largest absorbed dose (94.7 ± 13.6 μSv/MBq). The mean absorbed doses of the other organs were equal to or less than those from other hypoxia tracers. The excretion of radioactivity via the urinary system was very rapid, reaching 86.4 ± 7.1% of the administered dose. For the preliminary clinical study, seven patients were subjected to [18F]FMISO and [18F]DiFA positron emission tomography (PET) at 48-h intervals to compare the two tracers' diagnostic ability for tumor hypoxia. The results of the tumor hypoxia evaluation by [18F]DiFA PET at 1 h and 2 h were not significantly different from those obtained with [18F]FMISO PET at 4 h ([18F]DiFA at 1 h, p = 0.32; [18F]DiFA at 2 h, p = 0.08). Moreover, [18F]DiFA PET at both 1 h (k = 0.68) and 2 h (k = 1.00) showed better inter-observer reproducibility than [18F]FMISO PET at 4 h (k = 0.59). CONCLUSION: [18F]DiFA is well tolerated, and its radiation dose is comparable to those of other hypoxia tracers. [18F]DiFA is very rapidly cleared via the urinary system. [18F]DiFA PET generated comparable images to [18F]FMISO PET in hypoxia imaging with shorter waiting time, demonstrating the promising potential of [18F]DiFA PET for hypoxia imaging and for a multicenter trial.
  • Osamu Manabe, Markus Kroenke, Tadao Aikawa, Atsuto Murayama, Masanao Naya, Atsuro Masuda, Noriko Oyama-Manabe, Kenji Hirata, Shiro Watanabe, Tohru Shiga, Chietsugu Katoh, Nagara Tamaki
    Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology 26 (3) 909 - 918 1071-3581 2019/06 [Refereed][Not invited]
     
    OBJECTIVE: FDG PET/CT plays a significant role in the diagnosis of inflammatory heart diseases and cardiac tumors. We attempted to determine the optimal FDG uptake threshold for volume-based analyses and to evaluate the relationship between the myocardial physiological uptake volume in FDG PET and several clinical factors. METHODS: A total of 190 patients were retrospectively analyzed. The cardiac metabolic volume (CMV) was defined as a volume within the boundary determined by a threshold (SUVmean of blood pool × 1.5). RESULTS: The SUVmean of the blood pool measured in the descending aorta (DA) (r = 0.86, intraclass correlation coefficient [ICC] = 0.93, P < 0.0001) and that in the left ventricle (LV) cavity (r = 0.87, ICC = 0.90, P < 0.0001) showed high inter-operator reproducibility. However, the SUVmean in the LV cavity showed a significant correlation with the CMV (P = 0.0002, r = 0.26). The CMV in the patients who fasted < 18 hours were significantly higher (49.7  ±  73.2 vs. 18.0  ±  53.8 mL, P = 0.0013) compared to the patients with > 18-hour fasting. The multivariate analysis demonstrated that only the fasting period > 18 hours was independently associated with CMV = 0. CONCLUSION: Our findings revealed that the DA is suitable to decide the threshold for the volume-based analysis. The fasting time was significantly associated with the cardiac FDG uptake.
  • Osamu Manabe, Hiroshi Ohira, Kenji Hirata, Souichiro Hayashi, Masanao Naya, Ichizo Tsujino, Tadao Aikawa, Kazuhiro Koyanagawa, Noriko Oyama-Manabe, Yuuki Tomiyama, Keiichi Magota, Keiichiro Yoshinaga, Nagara Tamaki
    European journal of nuclear medicine and molecular imaging 46 (6) 1240 - 1247 2019/06 [Refereed][Not invited]
     
    PURPOSE: 18F-fluorodeoxyglocose positron emission tomography (FDG PET) plays a significant role in the diagnosis of cardiac sarcoidosis (CS). Texture analysis is a group of computational methods for evaluating the inhomogeneity among adjacent pixels or voxels. We investigated whether texture analysis applied to myocardial FDG uptake has diagnostic value in patients with CS. METHODS: Thirty-seven CS patients (CS group), and 52 patients who underwent FDG PET/CT to detect malignant tumors with any FDG cardiac uptake (non-CS group) were studied. A total of 36 texture features from the histogram, gray-level co-occurrence matrix (GLCM), gray-level run length matrix (GLRLM), gray-level zone size matrix (GLZSM) and neighborhood gray-level difference matrix (NGLDM), were computed using polar map images. First, the inter-operator and inter-scan reproducibility of the texture features of the CS group were evaluated. Then, texture features of the patients with CS were compared to those without CS lesions. RESULTS: Twenty-eight of the 36 texture features showed high inter-operator reproducibility with intraclass correlation coefficients (ICCs) over 0.80. In addition, 17 of the 36 showed high inter-scan reproducibility with ICCs over 0.80. The SUVmax showed no difference between the CS and non-CS group [7.36 ± 2.77 vs. 8.78 ± 4.65, p = 0.45, area under the curve (AUC) = 0.60]. By contrast, 16 of the 36 texture features could distinguish CS from non-CS grsoup with AUC > 0.80. Multivariate logistic regression analysis after hierarchical clustering concluded that long-run emphasis (LRE; P = 0.0004) and short-run low gray-level emphasis (SRLGE; P = 0.016) were significant independent factors that could distinguish between the CS and non-CS groups. Specifically, LRE was significantly higher in CS than in non-CS (30.1 ± 25.4 vs. 11.4 ± 4.6, P < 0.0001), with high diagnostic ability (AUC = 0.91), and had high inter-operator reproducibility (ICC = 0.98). CONCLUSIONS: The texture analysis had high inter-operator and high inter-scan reproducibility. Some of texture features showed higher diagnostic value than SUVmax for CS diagnosis. Therefore, texture analysis may have a role in semi-automated systems for diagnosing CS.
  • Keisuke Kawauchi, Kenji Hirata, Chietsugu Katoh, Seiya Ichikawa, Osamu Manabe, Kentaro Kobayashi, Shiro Watanabe, Sho Furuya, Tohru Shiga
    Scientific reports 9 (1) 7192 - 7192 2019/05/10 [Refereed][Not invited]
     
    Patient misidentification in imaging examinations has become a serious problem in clinical settings. Such misidentification could be prevented if patient characteristics such as sex, age, and body weight could be predicted based on an image of the patient, with an alert issued when a mismatch between the predicted and actual patient characteristic is detected. Here, we tested a simple convolutional neural network (CNN)-based system that predicts patient sex from FDG PET-CT images. This retrospective study included 6,462 consecutive patients who underwent whole-body FDG PET-CT at our institute. The CNN system was used for classifying these patients by sex. Seventy percent of the randomly selected images were used to train and validate the system; the remaining 30% were used for testing. The training process was repeated five times to calculate the system's accuracy. When images for the testing were given to the learned CNN model, the sex of 99% of the patients was correctly categorized. We then performed an image-masking simulation to investigate the body parts that are significant for patient classification. The image-masking simulation indicated the pelvic region as the most important feature for classification. Finally, we showed that the system was also able to predict age and body weight. Our findings demonstrate that a CNN-based system would be effective to predict the sex of patients, with or without age and body weight prediction, and thereby prevent patient misidentification in clinical settings.
  • Ren Togo, Takahiro Ogawa, Osamu Manabe, Kenji Hirata, Tohru Shiga, Miki Haseyama
    2019 IEEE 1st Global Conference on Life Sciences and Technologies, LifeTech 2019 237 - 238 2019/03 [Refereed][Not invited]
     
    © 2019 IEEE. This paper presents a method for extracting important regions for deep learning models in the identification of cardiac sarcoidosis using polar map images. Although deep learning-based detection methods have widely studied, they are still often called black boxes. Since high reliability for provided results from computer-aided diagnosis systems is important toward clinical applications, this problem should be solved. In this paper, we try to visualize important regions for deep learning-based models for improvement of understanding to clinicians. We monitor the variance of confidence of a model constructed with a deep learning-based feature and define it as a contribution value toward the estimated label. We visualize important regions for models based on the contribution value.
  • メルケル細胞癌におけるPET-CTのFDG集積に関する細胞学的検討
    北村 真也, 柳 輝希, 高島 有香, 今福 恵輔, 秦 洋郎, 清水 宏, 平田 健司, 上原 治朗, 石田 雄大, 大塚 篤司
    日本皮膚科学会雑誌 (公社)日本皮膚科学会 129 (3) 353 - 353 0021-499X 2019/03
  • Hajime Senjo, Minoru Kanaya, Koh Izumiyama, Koichiro Minauchi, Kenji Hirata, Akio Mori, Makoto Saito, Masanori Tanaka, Hiroaki Iijima, Eriko Tsukamoto, Kazuo Itoh, Shuichi Ota, Masanobu Morioka, Daigo Hashimoto, Takanori Teshima
    Cancer medicine 8 (3) 953 - 962 2019/03 
    Diffuse large B-cell lymphoma (DLBCL) is the most frequent subtype of non-Hodgkin lymphoma. High total metabolic tumor volume (TMTV) calculated using 18 F-FDG PET/CT images at diagnosis predicts poor prognosis of patients with DLBCL. However, high cost and poor access to the imaging facilities hamper wider use of 18 F-FDG PET/CT. In order to explore a surrogate marker for TMTV, we evaluated the correlation between the serum levels of soluble interleukin-2 receptor (sIL-2R) and TMTV in 64 patients with DLBCL, and the results were verified in an independent validation cohort of 86 patients. Serum levels of sIL-2R were significantly correlated with TMTV. ROC analysis revealed that the cutoff value of TMTV ≥150 cm3 or sIL-2R ≥ 1300 U/mL could predict failure to achieve EFS24 with areas under the curve (AUC) 0.706 and 0.758, respectively. Each of TMTV ≥150 cm3 and sIL-2R ≥1300 U/mL was significantly associated with worse 5-year overall survival and event-free survival. Importantly, each of sIL-2R <1300 U/mL or TMTV <150 cm3 identified patients with favorable prognosis among NCCN-IPI high-intermediate and high-risk group. Serum level of sIL-2R represents a convenient surrogate marker to estimate metabolic tumor burden measured by 18 F-FDG PET/CT that can predict treatment outcomes of patients with DLBCL.
  • Yasuyuki Fujita, Ken Natsuga, Osamu Manabe, Kenji Hirata, Hiroshi Shimizu
    Clinical nuclear medicine 44 (3) 244 - 245 2019/03 [Refereed][Not invited]
     
    A 34-year-old Japanese woman presented with widespread scaly erythema that had enlarged over 2 years. A skin biopsy revealed the diagnosis of mycosis fungoides (patch stage, T1b N0 M0 B0), a most frequent cutaneous T-cell lymphoma. F-FDG PET/CT scan unexpectedly showed intense uptake on the left sole, which suggested a tumorous mycosis fungoides lesion (SUVmax = 6.2). Careful examination revealed the mass to be a typical plantar wart of 2 cm in diameter that the patient had not recognized. With repeated cryotherapy, the wart disappeared in 6 months, and follow-up F-FDG PET/CT showed no abnormal uptake on the left sole.
  • Kroenke M, Hirata K, Gafita A, Watanabe S, Okamoto S, Magota K, Shiga T, Kuge Y, Tamaki N
    PloS one 14 (2) e0213111  2019 [Refereed][Not invited]
     
    BACKGROUND: Hypoxia can induce radiation resistance and is an independent prognostic marker for outcome in head and neck cancer. As 18F-FMISO (FMISO), a hypoxia tracer for PET, is far less common than 18F-FDG (FDG) and two separate PET scans result in doubled cost and radiation exposure to the patient, we aimed to predict hypoxia from FDG PET with new techniques of voxel based analysis and texture analysis. METHODS: Thirty-eight patients with head-and-neck cancer underwent consecutive FDG and FMISO PET scans before any treatment. ROIs enclosing the primary cancer were compared in a voxel-by-voxel manner between FDG and FMISO PET. Tumour hypoxia was defined as the volume with a tumour-to-muscle ratio (TMR) > 1.25 in the FMISO PET and hypermetabolic volume was defined as >50% SUVmax in the FDG PET. The concordance rate was defined as percentage of voxels within the tumour which were both hypermetabolic and hypoxic. 38 different texture analysis (TA) parameters were computed based on the ROIs and correlated with presence of hypoxia. RESULTS: Within the hypoxic tumour regions, the FDG uptake was twice as high as in the non-hypoxic tumour regions (SUVmean 10.9 vs. 5.4; p<0.001). A moderate correlation between FDG and FMISO uptake was found by a voxel-by-voxel comparison (r = 0.664 p<0.001). The average concordance rate was 25% (± 22%). Entropy was the TA parameter showing the highest correlation with hypoxia (r = 0.524 p<0.001). CONCLUSION: FDG uptake was higher in hypoxic tumour regions than in non-hypoxic regions as expected by tumour biology. A moderate correlation between FDG and FMISO PET was found by voxel-based analysis. TA yielded similar results in FDG and FMISO PET. However, it may not be possible to predict tumour hypoxia even with the help of texture analysis.
  • Ren Togo, Kenji Hirata, Osamu Manabe, Hiroshi Ohira, Ichizo Tsujino, Keiichi Magota, Takahiro Ogawa, Miki Haseyama, Tohru Shiga
    Computers in biology and medicine 104 81 - 86 2019/01 [Refereed][Not invited]
     
    AIMS: The aim of this study was to determine whether deep convolutional neural network (DCNN)-based features can represent the difference between cardiac sarcoidosis (CS) and non-CS using polar maps. METHODS: A total of 85 patients (33 CS patients and 52 non-CS patients) were analyzed as our study subjects. One radiologist reviewed PET/CT images and defined the left ventricle region for the construction of polar maps. We extracted high-level features from the polar maps through the Inception-v3 network and evaluated their effectiveness by applying them to a CS classification task. Then we introduced the ReliefF algorithm in our method. The standardized uptake value (SUV)-based classification method and the coefficient of variance (CoV)-based classification method were used as comparative methods. RESULTS: Sensitivity, specificity and the harmonic mean of sensitivity and specificity of our method with the ReliefF algorithm were 0.839, 0.870 and 0.854, respectively. Those of the SUVmax-based classification method were 0.468, 0.710 and 0.564, respectively, and those of the CoV-based classification method were 0.655, 0.750 and 0.699, respectively. CONCLUSION: The DCNN-based high-level features may be more effective than low-level features used in conventional quantitative analysis methods for CS classification.
  • N Fujima, K Hirata, T Shiga, R Li, K Yasuda, R Onimaru, K Tsuchiya, S Kano, T Mizumachi, A Homma, K Kudo, H Shirato
    Clinical radiology 73 (12) 1059.e1-1059.e8  2018/12 [Refereed][Not invited]
     
    AIM: To assess potential prognostic factors in pharynx squamous cell carcinoma (SCC) patients by quantitative morphological and intratumoural characteristics obtained by 2-[18F]-fluoro-2-deoxy-d-glucose positron-emission tomography/computed tomography (FDG-PET/CT). MATERIALS AND METHODS: The cases of 54 patients with pharynx SCC who underwent chemoradiation therapy were analysed retrospectively. Using their FDG-PET data, the quantitative morphological and intratumoural characteristics of 14 parameters were calculated. The progression-free survival (PFS) and overall survival (OS) information was obtained from patient medical records. Univariate and multivariate analyses were performed to assess the 14 quantitative parameters as well as the T-stage, N-stage, and tumour location data for their relation to PFS and OS. When an independent predictor was suggested in the multivariate analysis, the parameter was further assessed using the Kaplan-Meier method. RESULTS: In the assessment of PFS, the univariate and multivariate analyses indicated the following as independent predictors: the texture parameter of homogeneity and the morphological parameter of sphericity. In the Kaplan-Meier analysis, the PFS rate was significantly improved in the patients who had both a higher value of homogeneity (p=0.01) and a higher value of sphericity (p=0.002). With the combined use of homogeneity and sphericity, the patients with different PFS rates could be divided more clearly. CONCLUSION: The quantitative parameters of homogeneity and sphericity obtained by FDG-PET can be useful for the prediction of the PFS of pharynx SCC patients, especially when used in combination.
  • 15O-水心筋血流PETにおけるMonte Carlo scaling複合型SSS散乱補正の検討
    孫田 惠一, 志賀 哲, 真鍋 治, 納谷 昌直, 相川 忠夫, 新山 大樹, 平田 健司, 加藤 千恵次, 藤田 勝久, 玉木 長良
    核医学 (一社)日本核医学会 55 (Suppl.) S212 - S212 0022-7854 2018/11 [Refereed][Not invited]
  • Sho Furuya, Osamu Manabe, Hiroshi Ohira, Kenji Hirata, Tadao Aikawa, Masanao Naya, Ichizo Tsujino, Kazuhiro Koyanagawa, Toshihisa Anzai, Noriko Oyama-Manabe, Tohru Shiga
    EJNMMI research 8 (1) 94 - 94 2018/10/05 [Refereed][Not invited]
     
    BACKGROUND: Cardiac sarcoidosis (CS) is a rare but potentially life-threatening disease that causes conduction disturbance, systolic dysfunction, and, most notably, sudden cardiac death. 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) plays important roles not only in diagnosing CS but also in evaluating the effects of anti-inflammatory therapy. A volume-based analysis of parameters measured by FDG PET, so-called cardiac metabolic volume (CMV), has emerged as a new assessment tool. CMV is measured as the volume within the boundary determined by a reference tissue such as the liver and the blood pool uptake. However, there is a possibility that oral steroid therapy could lead to variations of the liver and the blood pool uptake. Here, we attempted to evaluate the steroid effects on the liver and the blood pool uptake. A total of 38 CS patients who underwent FDG PET/CT before and during steroid therapy were retrospectively enrolled. Volumes of interest (VOIs) were placed in the right lobe of the liver and descending aorta (DA). The maximum standardized uptake value (SUVmax), SUVmean, and SUVpeak of the liver and DA were compared between time points before and during steroid therapy. RESULTS: The SUVmax, SUVmean, and SUVpeak of the liver during steroid therapy significantly increased from the time point before the therapy (SUVmax 3.5 ± 0.4 vs. 3.8 ± 0.6, p = 0.014; SUVmean 2.7 ± 0.3 vs. 3.0 ± 0.5, p = 0.0065; SUVpeak 3.0 ± 0.4 vs. 3.4 ± 0.6, p = 0.006). However, the SUVmax, SUVmean, and SUVpeak in the DA did not significantly change (SUVmax 2.2 ± 0.3 vs. 2.2 ± 0.4, p = 0.46; SUVmean 1.9 ± 0.3 vs. 2.0 ± 0.4, p = 0.56; SUVpeak 2.0 ± 0.3 vs. 2.0 ± 0.3, p = 0.70). CONCLUSIONS: We measured FDG uptake in the liver and blood pool before and during steroid therapy. Steroid therapy increased the liver uptake but not the blood pool uptake. Our findings suggested that the DA uptake is a more suitable threshold than liver uptake to evaluate therapeutic effects using volume-based analysis of cardiac FDG PET.
  • Kitao T, Shiga T, Hirata K, Sekizawa M, Takei T, Yamashiro K, Tamaki N
    Annals of nuclear medicine 33 (1) 22 - 31 0914-7187 2018/09 [Refereed][Not invited]
     
    INTRODUCTION: Soft-tissue sarcomas (STS) are rare types of tumors that have variable levels of tumor differentiation. F-18 fluorodeoxyglucose positron emission tomography (FDG PET) has been established as an useful tool for STS patients, and the metabolic tumor volume (MTV) and total lesion glycolysis (TLG) are reported to be useful in various cancers. We compared the diagnostic value of four PET parameters (maximum standardized uptake value [SUVmax], SUVmean, MTV, and TLG) from two acquisition timings for predicting the expression of the pathological marker of cell proliferation Ki-67, based on pathological investigation. MATERIALS AND METHODS: In this retrospective study, we investigated 20 patients (59 ± 19 years old, 18-87 years old) with pathologically confirmed STS who underwent FDG PET before surgical intervention. The patients fasted ≥ 6 h before the intravenous injection of FDG. The whole body was scanned twice; at an early phase (61.5 ± 2.6 min) and at a delayed phase (118.0 ± 2.1 min) post-injection. The SUVmax, SUVmean, MTV, and TLG of the primary lesion were measured with a tumor boundary determined by SUV ≥ 2.0. Ki-67 was measured using MIB-1 immunohistochemistry. We used Pearson's correlation coefficient to analyze the relationships between the PET parameters and Ki-67 expressions. The Kaplan-Meier analysis with the log-rank test was performed to compare overall survival between high-group and low-group at each of the four PET parameters and Ki-67 expression. RESULTS: All four PET parameters at each phase showed significant correlations with Ki-67. Among them, the Pearson's correlation coefficient (r) was largest for TLG (r = 0.76 and 0.77 at the early and delayed phases, respectively), followed by MTV (0.70 and 0.72), SUVmax (r = 0.65 and 0.66), and SUVmean (r = 0.62 and r = 0.64). From early to delayed phases, the SUVmax and SUVmean both increased in all 20 patients, whereas the MTV and TLG increased in 13/20 (65%) and 16/20 (80%) patients, respectively. None of the %increases of the PET parameters were significantly correlated with Ki-67. The overall survival was shorter for high-SUVmax, high-SUVmean, high-TLG, and high-Ki-67 groups than the other groups, although the difference did not reach statistical significance. CONCLUSION: The SUVmax, SUVmean, MTV, and TLG acquired at both 1 and 2 h after injection showed significant correlations with Ki-67. Among them, correlation coefficient with Ki-67 expression was highest for TLG, although the best parameter should be determined in a larger population. The delayed-phase FDG PET was equally useful as that of early-phase to predict tumor aggressiveness in STS.
  • Noriyuki Fujima, Kenji Hirata, Tohru Shiga, Koichi Yasuda, Rikiya Onimaru, Kazuhiko Tsuchiya, Satoshi Kano, Takatsugu Mizumachi, Akihiro Homma, Kohsuke Kudo, Hiroki Shirato
    Quantitative imaging in medicine and surgery 8 (8) 788 - 795 2223-4292 2018/09 [Refereed][Not invited]
     
    Background: To investigate the utility of quantitative morphological and intratumoral characteristics obtained by 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (FDG-PET/CT) for the prediction of treatment outcome in patients with nasal or paranasal cavity squamous cell carcinoma (SCC). Methods: Twenty-four patients with nasal or paranasal cavity SCC who received curative non-surgical therapy (a combination of super-selective arterial cisplatin infusion and radiotherapy) were retrospectively analyzed. From pre-treatment FDG-PET data, a total of 13 parameters of quantitative morphological characteristics (tumor volume, surface area and sphericity), intratumoral characteristics (the maximum and mean standard uptake value, three intratumoral histogram and four textural parameters) and total lesion glycolysis (TLG) were respectively calculated. Information regarding the treatment outcome was determined from the histological diagnosis or clinical follow-up. Each of the 13 quantitative parameters as well as T- and N-stage was assessed for its relation to treatment outcome of local control or failure. Results: In univariate analysis, significant differences in surface area and sphericity between the local control and failure groups were observed. The receiver operating characteristic (ROC) curve analysis showed that sphericity had the highest accuracy of 0.88. In the multivariate analysis, sphericity was revealed as an independent predictor of the local control or failure. Conclusions: The quantitative parameters of sphericity are useful to predict the treatment outcome in patients with nasal or paranasal SCC.
  • Takeuchi S, Shiga T, Hirata K, Taguchi J, Magota K, Ariga S, Gouda T, Ohhara Y, Homma R, Shimizu Y, Kinoshita I, Tsuji Y, Homma A, Iijima H, Tamaki N, Dosaka-Akita H
    BMJ open 8 (8) e021001  2018/08 [Refereed][Not invited]
     
    INTRODUCTION: Lenvatinib, an oral molecular targeted drug, is used to treat patients with unresectable or advanced thyroid carcinoma that is refractory to radioiodine treatment. Effective methods for evaluating molecular targeted drugs are a critical unmet need owing to their expensive costs and unique adverse events. The aim of this study is to determine whether 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT at 1 week after commencing lenvatinib can predict treatment outcomes. DESIGN AND METHODS: This study is planned as a non-randomised single-arm multicentre study; patients with pathologically confirmed differentiated thyroid carcinoma (DTC) with lesions that are refractory to radioiodine treatment are eligible. The main exclusion criteria are medullary or anaplastic carcinoma, prior treatment with chemotherapy, poor general condition and thromboembolism-requiring treatment. Patients to be included in the study will be treated with lenvatinib and undergo FDG-PET/CT examination twice: before and 1 week after the initiation of treatment. Contrast-enhanced CT, the gold standard for evaluation, will be performed at least 4 weeks after the initiation of treatment. The primary objective is to evaluate the ability of the lesion maximum standard uptake value for FDG PET/CT performed 1 week after the initiation of treatment to predict outcomes compared with the response evaluation obtained via contrast-enhanced CT performed at least 4 weeks after the initiation of treatment. ETHICS AND DISSEMINATION: This study is conducted in accordance with the Declaration of Helsinki and has received ethical approval from the institutional review board of the Hokkaido University Hospital (approval number: 015-402). The results of this study will be disseminated through a presentation at a conference and the publication of the data in a peer-reviewed journal. The study will be implemented and reported in line with the SPIRIT statement. TRIAL REGISTRATION NUMBER: UMIN000022592.
  • Shigeru Yamaguchi, Yukitomo Ishi, Hiroaki Motegi, Michinari Okamoto, Hiroyuki Kobayashi, Kenji Hirata, Yoshitaka Oda, Shinya Tanaka, Shunsuke Terasaka, Kiyohiro Houkin
    Journal of neurosurgical sciences 64 (6) 502 - 508 0390-5616 2018/07/09 [Refereed][Not invited]
     
    BACKGROUND: Although newly diagnosed high-grade glioma patients in Japan can receive bevacizumab (BEV) as first-line chemotherapy, randomized clinical trials have not shown a survival benefit for BEV for these patients. In this study, we investigated whether selective add-on BEV for patients with newly diagnosed glioblastoma (GBM) and anaplastic astrocytoma (AA) improves prognosis, in cases where tumors were continuously growing during radiotherapy concomitant with temozolomide (TMZ). METHODS: We conducted a retrospective survey of the overall survival (OS) of patients with GBM/AAs who were treated in our institution between 2006 and 2016. Patients whose tumors were continuously growing regardless of radiotherapy were categorized as the "progressive" group; remaining patients were categorized as the "non-progressive" group. Since 2013, patients in the "progressive" group received add-on BEV therapy with the Stupp regimen during or just after radiotherapy. RESULTS: Of 151 GBM/AA patients, 34 (22.5%) were categorized in the "progressive" group. Median OSs of the "progressive" and "non-progressive" groups were 13.2 months and 25.3 months, respectively (P < 0.001). Twelve patients in the "progressive" group received add-on BEV therapy, and their median OS was 20.2 months; whereas for the remaining 22 patients in the "progressive" group who were treated before the BEV era, their median OS was 10.5 months. In the "progressive" group, add-on BEV significantly extended OS (P = 0.018) and was the lone clinical factor of better prognosis. CONCLUSIONS: We found that, for patients with GBM/AAs whose tumors were continuously growing during radiotherapy, add-on BEV treatment resulted in survival benefits.
  • 絹谷 清剛, 西山 佳宏, 加藤 隆司, 萱野 大樹, 佐藤 修平, 田代 学, 巽 光朗, 橋本 禎介, 馬場 眞吾, 平田 健司, 吉村 真奈, 米山 寛人, (公社)日本アイソトープ協会医学・薬学部会全国核医学診療実態調査専門委員会
    Radioisotopes (公社)日本アイソトープ協会 67 (7) 339 - 387 0033-8303 2018/07 [Not refereed][Not invited]
     
    日本アイソトープ協会では1982年から5年ごとに専門委員会を設けて全国核医学診療実態調査を行っており、第8回調査を2017年6月に行った。回答回収率は90%超であった。年間推定件数は単光子放出核種を用いた核医学検査が前回より5.7%減少した一方で、PET検査は約24.5%増加した。この結果、核医学検査総数は4.1%増加した。非密封RIを用いた核医学治療は223Ra治療開始と甲状腺癌治療の増加により全体で34.1%増加した。近年核医学診療の意義が変化していることが示された。(著者抄録)
  • Use of deep convolutional neural network-based features for detection of cardiac sarcoidosis from polar map
    Ren Togo, Kenji Hirata, Osamu Manabe, Hiroshi Ohira, Ichizo Tsujino, Takahiro Ogawa, Miki Haseyama, Tohru Shiga
    Society of Nuclear Medicine and Molecular Imaging Annual Meeting (SNMMI) 2018/06 [Refereed][Not invited]
  • Keisuke Kawauchi, Kenji Hirata, Seiya Ichikawa, Osamu Manabe, Kentaro Kobayashi, Shiro Watanabe, Miki Haseyama, Takahiro Ogawa, Ren Togo, Tohru Shiga, Chietsugu Katoh
    JOURNAL OF NUCLEAR MEDICINE 59 0161-5505 2018/05 [Refereed][Not invited]
  • J. Sato, Y. Kitagawa, S. Watanabe, T. Asaka, N. Ohga, K. Hirata, T. Shiga, A. Satoh, N. Tamaki
    International Journal of Oral and Maxillofacial Surgery 47 (5) 553 - 560 0901-5027 2018/05/01 [Not refereed][Not invited]
     
    © 2017 International Association of Oral and Maxillofacial Surgeons Tumour hypoxia can be detected by 18 F-fluoromisonidazole positron emission tomography (FMISO-PET). Few studies have assessed the relationships of new PET parameters, including hypoxic volume (HV), metabolic tumour volume (MTV), and total lesion glycolysis (TLG), with 5-year survival of patients treated surgically for oral squamous cell carcinoma (OSCC). This study evaluated the relationships between these PET parameters and 5-year survival in OSCC patients. Twenty-three patients (age 42–84 years; 15 male, eight female) with OSCC underwent FMISO- and 18 F-fluoro-2-deoxyglucose (FDG)-PET computed tomography before surgery. All of them underwent radical surgery and were followed up for more than 5 years. The FDG-PET maximum standardized uptake value (SUV max ), HV, MTV, and TLG were measured. The ability of PET parameters to predict disease-free survival (DFS) and loco-regional recurrence (LR) was evaluated using receiver operating characteristic curve analysis. During the follow-up period, five of the 23 patients (22%) died and six (26%) experienced LR. Although FDG-PET SUV max was not significantly associated with DFS or LR, HV correlated significantly with both DFS and LR. TLG, but not MTV, was significantly associated with DFS; however neither MTV nor TLG was related significantly to LR. In conclusion, tumour HV may predict outcomes in patients with OSCC.
  • Abiko K, Shiga T, Katoh C, Hirata K, Kuge Y, Kobayashi K, Ikeda S, Ikoma K
    Brain injury 32 (11) 1367 - 1372 0269-9052 2018 [Refereed][Not invited]
     
    OBJECTIVE: Cerebral metabolism may play a significant role in neurobehavioural disability following traumatic brain injury (TBI). In this study, we examined the relationship between intelligence quotient (IQ) and the cerebral metabolic rate of oxygen (CMRO2) in the lateral prefrontal cortex, which was measured by 15O-labelled gas positron emission tomography (PET), in patients with TBI. MATERIALS AND METHODS: The subjects were 12 patients (eight males and four females) who suffered from neurobehavioural disability following TBI. Their mean age was 33.3 years. The cause of injury was traffic accidents in all patients and the mean period after injury was 44.8 months. These patients underwent 15O-labelled gas PET and tests using either the Wechsler Adult Intelligence Scale-Revised (WAIS-R) or the Wechsler Intelligence Scale for Children-Revised (WISC-R). Pearson's correlation between CMRO2 and total IQ (TIQ) was calculated. RESULTS: A statistically significant correlation was observed between TIQ and CMRO2 in the right Brodmann areas (BAs) 44 and 45. The lower the WAIS score, the higher the CMRO2 in both areas. CONCLUSION: Neurological function negatively correlated with the metabolism of oxygen. It was possible that changes in brain networks increased the neuronal activity in the undamaged areas and that the increased activity compensated for the function decline.
  • Yuji Hiroshima, Osamu Manabe, Masanao Naya, Yuuki Tomiyama, Keiichi Magota, Masahiko Obara, Tadao Aikawa, Noriko Oyama-Manabe, Keiichiro Yoshinaga, Kenji Hirata, Markus Kroenke, Nagara Tamaki, Chietsugu Katoh
    Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology 27 (4) 1118 - 1125 1071-3581 2017/12/21 [Refereed][Not invited]
     
    BACKGROUND: 11C-hydroxyephedrine (HED) PET has been used to evaluate the myocardial sympathetic nervous system (SNS). Here we sought to establish a simultaneous approach for quantifying both myocardial blood flow (MBF) and the SNS from a single HED PET scan. METHODS: Ten controls and 13 patients with suspected cardiac disease were enrolled. The inflow rate of 11C-HED (K1) was obtained using a one-tissue-compartment model. We compared this rate with the MBF derived from 15O-H2O PET. In the controls, the relationship between K 1 from 11C-HED PET and the MBF from 15O-H2O PET was linked by the Renkin-Crone model. RESULTS: The relationship between K 1 from 11C-HED PET and the MBF from 15O-H2O PET from the controls' data was approximated as follows: K 1  =  (1 - 0.891 * exp(- 0.146/MBF)) * MBF. In the validation set, the correlation coefficient demonstrated a significantly high relationship for both the whole left ventricle (r = 0.95, P < 0.001) and three coronary territories (left anterior descending artery: r = 0.96, left circumflex artery: r = 0.81, right coronary artery: r =  0.86; P < 0.001, respectively). CONCLUSION: 11C-HED can simultaneously estimate MBF and sympathetic nervous function without requiring an additional MBF scan for assessing mismatch areas between MBF and SNS.
  • Satoshi Yabusaki, Noriko Oyama-Manabe, Osamu Manabe, Kenji Hirata, Fumi Kato, Noriyuki Miyamoto, Yoshihiro Matsuno, Kohsuke Kudo, Nagara Tamaki, Hiroki Shirato
    EJNMMI research 7 (1) 20 - 20 2017/12 [Refereed][Not invited]
     
    BACKGROUND: We aimed to assess the positivity, distribution, quantitative degree of vessel inflammation, and clinical characteristics of IgG4-related aortitis/periarteritis and periarteritis (IgG4-aortitis), and to examine the difference in these characteristics between cases with and without IgG4-aortitis, using fluorodeoxyglucose positron-emission tomography/computed tomography (FDG-PET/CT) co-registered with contrast-enhanced CT (CECT). We retrospectively evaluated 37 patients with IgG4-related disease (IgG4-RD) who underwent both FDG-PET/CT and CECT. The arterial SUVmax and its value normalized to the background venous blood pool (BP)-the target-to-background ratio (TBR) in the entire aorta and the major first branches-were measured. Active vascular inflammation was considered in cases with a higher FDG uptake than BP and a thickened arterial wall (>2 mm). RESULTS: Fifteen (41%) patients exhibited IgG4-aortitis. Most patients (80%) showed multiple region involvement. The entire aorta, including the major first branches, were involved, typically showing a thickened wall and high FDG uptakes. The most common site was the iliac arteries (35%), followed by the infrarenal abdominal aorta (33%), thoracic aorta (8%), first branches of the thoracic aorta (8%), suprarenal abdominal aorta (6%), and the first branches of the abdominal aorta (5%). The IgG4-aortitis-positive vessel regions were thickened, with an average maximal wall thickness of 6.3 ± 2.9 mm. The SUVmax and TBR values were significantly higher in the IgG4-aortitis-positive regions (median 3.7 [1.6-5.5] and 2.1 [1.4-3.7], respectively) than in the IgG4-aortitis-negative regions (median 2.1 [1.2-3.7] and 1.3 [0.9-2.3], respectively; p < 0.0001). The IgG4-aortitis-positive group patients were older (69.5 ± 6.0 vs. 63.3 ± 12.6 years, respectively) and had a higher male predominance (80 vs. 55%, respectively) than the negative group, although the differences were not significant (p = 0.17 and p = 0.06, respectively). CONCLUSIONS: We investigated the image characteristics of IgG4-aortitis. The entire aorta and major branches can be involved with more than 2-fold higher FDG uptake than the venous background pool, and with wall thickening. The most common involved site is the iliac arteries, followed by the infrarenal abdominal aorta.
  • Osamu Manabe, Masanao Naya, Tadao Aikawa, Masahiko Obara, Keiichi Magota, Markus Kroenke, Noriko Oyama-Manabe, Kenji Hirata, Daiki Shinyama, Chietsugu Katoh, Nagara Tamaki
    EJNMMI research 7 (1) 52 - 52 2017/12 [Refereed][Not invited]
     
    BACKGROUND: The quantification of myocardial blood flow (MBF) and coronary flow reserve (CFR) are useful approaches for evaluating the functional severity of coronary artery disease (CAD). 15O-water positron emission tomography (PET) is considered the gold standard method for MBF quantification. However, MBF measurements in 15O-water PET with three-dimensional (3D) data acquisition, attenuation correction using computed tomography (CT), and time of flight have not been investigated in detail or validated. We conducted this study to evaluate the diagnostic potential of MBF measurements using PET/CT for a comparison of a control group and patients suspected of having CAD. RESULTS: Twenty-four patients with known or suspected CAD and eight age-matched healthy volunteers underwent rest and pharmacological stress perfusion studies with 15O-water PET/CT. The whole and three regional (left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA) territory) MBF values were estimated. The CFR was computed as the ratio of the MBF during adenosine triphosphate-induced stress to the MBF at rest. The inter-observer variability was assessed by two independent observers. PET/CT using a 15O-water dose of 500 MBq and 3D data acquisition showed good image quality. A strong inter-observer correlation was detected in both the whole MBF analysis and the regional analysis with high intra-class correlation coefficients (r > 0.90, p < 0.001). Regional MBF at rest (LAD, 0.82 ± 0.15 ml/min/g; LCX, 0.83 ± 0.17 ml/min/g; RCA, 0.71 ± 0.20 ml/min/g; p = 0.74), MBF at stress (LAD, 3.77 ± 1.00 ml/min/g; LCX, 3.56 ± 1.01 ml/min/g; RCA, 3.27 ± 1.04 ml/min/g; p = 0.62), and CFR (LAD, 4.64 ± 0.90; LCX, 4.30 ± 0.64; RCA, 4.64 ± 0.96; p = 0.66) of the healthy volunteers showed no significant difference among the three regions. The global CFR of the patients was significantly lower than that of the volunteers (2.75 ± 0.81 vs. 4.54 ± 0.66, p = 0.0002). The regional analysis of the patients demonstrated that the CFR tended to be lower in the stenotic region compared to the non-stenotic region (2.43 ± 0.81 vs. 2.95 ± 0.92, p = 0.052). CONCLUSIONS: 15O-water PET/CT with 3D data acquisition can be reliably used for the quantification of functional MBF and CFR in CAD patients.
  • Keiichi Magota, Tohru Shiga, Yukari Asano, Daiki Shinyama, Jinghan Ye, Amy E. Perkins, Piotr J. Maniawski, Takuya Toyonaga, Kentaro Kobayashi, Kenji Hirata, Chietsugu Katoh, Naoya Hattori, Nagara Tamaki
    JOURNAL OF NUCLEAR MEDICINE 58 (12) 2020 - 2025 0161-5505 2017/12 [Refereed][Not invited]
     
    In 3-dimensional PET/CT imaging of the brain with O-15-gas inhalation, high radioactivity in the face mask creates cold artifacts and affects the quantitative accuracy when scatter is corrected by conventional methods (e.g., single-scatter simulation [SSS] with tailfitting scaling [TFS-SSS]). Here we examined the validity of a newly developed scatter-correction method that combines SSS with a scaling factor calculated by Monte Carlo simulation (MCS-SSS). Methods: We performed phantom experiments and patient studies. In the phantom experiments, a plastic bottle simulating a face mask was attached to a cylindric phantom simulating the brain. The cylindric phantom was filled with F-18-FDG solution (3.8-7.0 kBq/mL). The bottle was filled with nonradioactive air or various levels of F-18-FDG (0-170 kBq/mL). Images were corrected either by TFS-SSS or MCS-SSS using the CT data of the bottle filled with nonradioactive air. We compared the image activity concentration in the cylindric phantom with the true activity concentration. We also performed 15O-gas brain PET based on the steady-state method on patients with cerebrovascular disease to obtain quantitative images of cerebral blood flow and oxygen metabolism. Results: In the phantom experiments, a cold artifact was observed immediately next to the bottle on TFS-SSS images, where the image activity concentrations in the cylindric phantom were underestimated by 18%, 36%, and 70% at the bottle radioactivity levels of 2.4, 5.1, and 9.7 kBq/mL, respectively. At higher bottle radioactivity, the image activity concentrations in the cylindric phantom were greater than 98% underestimated. For the MCS-SSS, in contrast, the error was within 5% at each bottle radioactivity level, although the image generated slight high-activity artifacts around the bottle when the bottle contained significantly high radioactivity. In the patient imaging with O-15(2) and (CO2)-O-15 inhalation, cold artifacts were observed on TFS-SSS images, whereas no artifacts were observed on any of the MCS-SSS images. Conclusion: MCS-SSS accurately corrected the scatters in O-15-gas brain PET when the 3-dimensional acquisition mode was used, preventing the generation of cold artifacts, which were observed immediately next to a face mask on TFS-SSS images. The MCS-SSS method will contribute to accurate quantitative assessments.
  • Kazuhiro Kitajima, Masatoyo Nakajo, Hayato Kaida, Ryogo Minamimoto, Kenji Hirata, Masakatsu Tsurusaki, Hiroshi Doi, Yoshiko Ueno, Keitaro Sofue, Yukihisa Tamaki, Koichiro Yamakado
    Nagoya journal of medical science 79 (4) 527 - 543 0027-7622 2017/11 [Refereed][Not invited]
     
    Positron emission tomography/computed tomography (PET/CT) integrated with 2-[18F]fluoro-2-deoxy-D-glucose (FDG) is a useful tool for acquisition of both glucose metabolism and anatomic imaging data, as only a single device and one diagnostic session is required, thus opening a new field in clinical oncologic imaging. FDG-PET/CT has been successfully used for initial staging, restaging, assessment of early treatment response, evaluation of metastatic disease response, and prognostication of intestinal cancer as well as various malignant tumors. We reviewed the current status and role of FDG-PET/CT for management of patients with esophageal cancer, gastric cancer, and colorectal cancer, with focus on both its usefulness and limitations.
  • Takuya Toyonaga, Kenji Hirata, Tohru Shiga, Tamaki Nagara
    EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 44 (10) 1679 - 1681 1619-7070 2017/09 [Refereed][Not invited]
  • Tohru Shiga, Atsuro Suzuki, Kotarou Sakurai, Tsugiko Kurita, Wataru Takeuchi, Takuya Toyonaga, Kenji Hirata, Keiji Kobashi, Chietsugu Katoh, Naoki Kubo, Nagara Tamaki
    CLINICAL NUCLEAR MEDICINE 42 (9) 663 - 668 0363-9762 2017/09 [Refereed][Not invited]
     
    Purpose We developed a prototype CdTe SPECT system with 4-pixel matched collimator for brain study. This system provides high-energy-resolution (6.6%), high-sensitivity (220 cps/MBq/head), and high-spatial-resolution images. The aim of this study was to evaluate dual-isotope study of CBF and central benzodiazepine receptor (BZR) images using Tc-99m-ECD and I-123-IMZ with the new SPECT system in patients with epilepsy comparing with single-isotope study using the conventional scintillation gamma camera. Methods This study included 13 patients with partial epilepsy. The BZR images were acquired at 3 hours after I-123-IMZ injection for 20 minutes. The images of IMZ were acquired with a conventional 3-head scintillation gamma camera. After BZR image acquisition with the conventional camera, Tc-99m-ECD was injected, and CBF and BZR images were acquired simultaneously 5 minutes after ECD injection with the new SPECT system. The CBF images were also acquired with the conventional camera on separate days. The findings were visually analyzed, and 3D-SSP maximum Z scores of lesions were compared between the 2 studies. Results There were 47 abnormal lesions on BZR images and 60 abnormal lesions on CBF images in the single-isotope study with the conventional camera. Dual-isotope study with the new system showed concordant abnormal findings of 46 of 47 lesions on BZR and 54 of 60 lesions on CBF images with the single-isotope study with the conventional camera. There was high agreement between the 2 studies in both BZR and CBF findings (Cohen values = 0.96 for BZR and 0.78 for CBF). In semiquantitative analysis, maximum Z scores of dual-isotope study with the new system strongly correlated with those of single-isotope study with the conventional camera (BZR: r = 0.82, P < 0.05, CBF: r = 0.87, P < 0.05). Conclusions Our new SPECT system permits dual-isotope study for pixel-by-pixel analysis of CBF and BZR information with the same pathophysiological condition in patients with epilepsy.
  • Jun Sato, Yoshimasa Kitagawa, Shiro Watanabe, Takuya Asaka, Noritaka Ohga, Kenji Hirata, Shozo Okamoto, Tohru Shiga, Masanobu Shindoh, Yuji Kuge, Nagara Tamaki
    ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY 124 (3) 261 - 270 2212-4403 2017/09 [Refereed][Not invited]
     
    Objective. Hypoxia is a common feature and prognostic factor in cancer. F-18-fluoromisonidazole (FMISO) positron emission tomography (PET) can detect tumor hypoxia noninvasively. The aim of this study was to assess the correlations between FMISO-PET and F-18-fluorodexyglucose (FDG)-PET parameters with cell proliferation and hypoxia in patients with oral squamous cell carcinoma (OSCC). Study Design. Twenty-three preoperative patients with OSCC were included. The tumor/muscle ratio (TMR) of FMISO-PET, the maximum standardized uptake values (SUVmax) of FDG-PET, metabolic tumor volume, and total lesion glycolysis were measured. Ki-67 and hypoxia-inducible factor-1 alpha (HIF-1 alpha) expression was immunohistochemically evaluated. Results. FMISO TMR (P = .003) and FDG SUVmax (P = .04) were significantly higher in patients with high expression of Ki-67 compared with those with low expression of Ki-67. FMISO TMR (P = .006) and FDG SUVmax (P = .01) were also significantly higher in patients with HIF-1 alpha expression than in those without HIF-1 alpha expression. Metabolic tumor volume was not significantly related to either Ki-67 or HIF-1 alpha expression. Multivariate analysis showed that FMISO TMR was independently predictive of Ki-67 (P = .002; odds ratio 31.1) and HIF-1 alpha (P = .049; odds ratio 10.5) expression. Conclusions. FMISO-PET showed significant relationships with Ki-67 and HIF-1 alpha expression, which are key features of cell proliferation and hypoxia in OSCC.
  • 心サルコイドーシスにおけるFDG集積定量評価の再現性
    真鍋 治, 平田 健司, 大平 洋, 納谷 昌直, 相川 忠夫, 真鍋 徳子, 志賀 哲
    核医学 (一社)日本核医学会 54 (Suppl.) S174 - S174 0022-7854 2017/09 [Refereed][Not invited]
  • Toshihiro Homma, Osamu Manabe, Kazuomi Ichinokawa, Hiroko Yamashita, Noriko Oyama-Manabe, Fumi Kato, Kenji Hirata, Markus Kroenke, Nagara Tamaki
    Acta radiologica open 6 (7) 2058460117715665 - 2058460117715665 2017/07 [Refereed][Not invited]
     
    We report a case of breast cancer detected as an incidental finding on 99mTc-MIBI scintigraphy. 99mTc-MIBI scintigraphy is usually used to evaluate cardiac perfusion or to detect ectopic parathyroid adenomas; however, it is also known to sensitively detect breast cancer. Accordingly, a few reports have described the incidental detection of breast cancer by 99mTc-MIBI scintigraphy performed to detect parathyroid adenoma. Our present case underscores the importance of attending to any incidental findings when searching for parathyroid adenomas using 99mTc-MIBI scintigraphy.
  • Tadao Aikawa, Masanao Naya, Noriko Oyama-Manabe, Satoshi Maekawa, Hideo Nambu, Hirofumi Mitsuyama, Kenji Hirata, Hiromi Kanno-Okada, Hiroyuki Tsutsui
    JOURNAL OF NUCLEAR CARDIOLOGY 24 (3) 1107 - 1109 1071-3581 2017/06 [Refereed][Not invited]
  • Shiro Watanabe, Tohru Shiga, Kenji Hirata, Tetsuya Inoue, Shozo Okamoto, Takuya Toyonaga, Keiichi Magota, Ken-ichi Nishijima, Yuji Kuge, Nagara Tamaki
    JOURNAL OF NUCLEAR MEDICINE 58 0161-5505 2017/05 [Refereed][Not invited]
  • Takuya Toyonaga, Tohru Shiga, Kenji Hirata, Shigeru Yamaguchi, Wataru Takeuchi, Kohsuke Kudo, Keiichi Magota, Osamu Manabe, Kentaro Kobayashi, Shiro Watanabe, Yuji Kuge, Nagara Tamaki
    JOURNAL OF NUCLEAR MEDICINE 58 0161-5505 2017/05 [Refereed][Not invited]
  • Takuya Toyonaga, Shigeru Yamaguchi, Kenji Hirata, Kentaro Kobayashi, Osamu Manabe, Shiro Watanabe, Shunsuke Terasaka, Hiroyuki Kobayashi, Naoya Hattori, Tohru Shiga, Yuji Kuge, Shinya Tanaka, Yoichi M Ito, Nagara Tamaki
    European journal of nuclear medicine and molecular imaging 44 (4) 611 - 619 1619-7070 2017/04 [Refereed][Not invited]
     
    PURPOSE: Metabolic activity and hypoxia are both important factors characterizing tumor aggressiveness. Here, we used F-18 fluoromisonidazole (FMISO) and F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) to define metabolically active hypoxic volume, and investigate its clinical significance in relation to progression free survival (PFS) and overall survival (OS) in glioblastoma patients. EXPERIMENTAL DESIGN: Glioblastoma patients (n = 32) underwent FMISO PET, FDG PET, and magnetic resonance imaging (MRI) before surgical intervention. FDG and FMISO PET images were coregistered with gadolinium-enhanced T1-weighted MR images. Volume of interest (VOI) of gross tumor volume (GTV) was manually created to enclose the entire gadolinium-positive areas. The FMISO tumor-to-normal region ratio (TNR) and FDG TNR were calculated in a voxel-by-voxel manner. For calculating TNR, standardized uptake value (SUV) was divided by averaged SUV of normal references. Contralateral frontal and parietal cortices were used as the reference region for FDG, whereas the cerebellar cortex was used as the reference region for FMISO. FDG-positive was defined as the FDG TNR ≥1.0, and FMISO-positive was defined as FMISO TNR ≥1.3. Hypoxia volume (HV) was defined as the volume of FMISO-positive and metabolic tumor volume in hypoxia (hMTV) was the volume of FMISO/FDG double-positive. The total lesion glycolysis in hypoxia (hTLG) was hMTV × FDG SUVmean. The extent of resection (EOR) involving cytoreduction surgery was volumetric change based on planimetry methods using MRI. These factors were tested for correlation with patient prognosis. RESULTS: All tumor lesions were FMISO-positive and FDG-positive. Univariate analysis indicated that hMTV, hTLG, and EOR were significantly correlated with PFS (p = 0.007, p = 0.04, and p = 0.01, respectively) and that hMTV, hTLG, and EOR were also significantly correlated with OS (p = 0.0028, p = 0.037, and p = 0.014, respectively). In contrast, none of FDG TNR, FMISO TNR, GTV, HV, patients' age, or Karnofsky performance scale (KPS) was significantly correlated with PSF or OS. The hMTV and hTLG were found to be independent factors affecting PFS and OS on multivariate analysis. CONCLUSIONS: We introduced hMTV and hTLG using FDG and FMISO PET to define metabolically active hypoxic volume. Univariate and multivariate analyses demonstrated that both hMTV and hTLG are significant predictors for PFS and OS in glioblastoma patients.
  • Junichi Nakagawa, Osamu Manabe, Takatsugu Mizumachi, Hiromi Kanno-Okada, Kanako C Hatanaka, Tomoko Mitsuhashi, Noriko Oyama-Manabe, Kenji Hirata, Nagara Tamaki
    Clinical nuclear medicine 42 (3) e157-e160 - e160 0363-9762 2017/03 [Refereed][Not invited]
     
    Cartilaginous tumors of the larynx are uncommon neoplasms that sometimes mimic laryngeal cancers. There has been no report of F-FDG PET/CT for the evaluation of laryngeal cartilaginous tumors. We reported 3 cases of laryngeal cartilaginous tumors with the image findings, including CT, FDG PET/CT, and MRI and reviewed literatures. We concluded that the combination of a very high-signal mass on T2-weighted magnetic resonance images and lower FDG uptake might be diagnostic image characteristics for distinguishing laryngeal cartilaginous tumor from laryngeal cancer.
  • Kagari Abiko, Katsunori Ikoma, Tohru Shiga, Chietsugu Katoh, Kenji Hirata, Yuji Kuge, Kentaro Kobayashi, Nagara Tamaki
    EJNMMI RESEARCH 7 (1) 28  2191-219X 2017/03 [Refereed][Not invited]
     
    Background: Traumatic brain injury (TBI) causes brain dysfunction in many patients. Using C-11 flumazenil (FMZ) positron emission tomography (PET), we have detected and reported the loss of neuronal integrity, leading to brain dysfunction in TBI patients. Similarly to FMZ PET, I-123 iomazenil (IMZ) single photon emission computed tomography (SPECT) is widely used to determine the distribution of the benzodiazepine receptor (BZR) in the brain cortex. The purpose of this study is to examine whether IMZ SPECT is as useful as FMZ PET for evaluating the loss of neuronal integrity in TBI patients. The subjects of this study were seven patients who suffered from neurobehavioral disability. They underwent IMZ SPECT and FMZ PET. Nondisplaceable binding potential (BPND) was calculated from FMZ PET images. The uptake of IMZ was evaluated on the basis of lesion-to-pons ratio (LPR). The locations of low uptake levels were visually evaluated both in IMZ SPECT and FMZ PET images. We compared FMZ BPND and (LPR-1) of IMZ SPECT. Results: In the visual assessment, FMZ BPND decreased in 11 regions. In IMZ SPECT, low uptake levels were observed in eight of the 11 regions. The rate of concordance between FMZ PET and IMZ SPECT was 72.7%. The mean values IMZ (LPR-1) (1.95 +/- 1.01) was significantly lower than that of FMZ BPND (2.95 +/- 0.80 mL/mL). There was good correlation between FMZ BPND and IMZ (LPR-1) (r = 0.80). Conclusions: IMZ SPECT findings were almost the same as FMZ PET findings in TBI patients. The results indicated that IMZ SPECT is useful for evaluating the loss of neuronal integrity. Because IMZ SPECT can be performed in various facilities, IMZ SPECT may become widely adopted for evaluating the loss of neuronal integrity.
  • Atsuro Masuda, Osamu Manabe, Noriko Oyama-Manabe, Masanao Naya, Masahiko Obara, Mamoru Sakakibara, Kenji Hirata, Satoshi Yamada, Tomoaki Naka, Hiroyuki Tsutsui, Nagara Tamaki
    Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology 24 (1) 323 - 324 1071-3581 2017/02 [Refereed][Not invited]
  • Osamu Manabe, Kenji Hirata, Okamoto Shozo, Tohru Shiga, Yuko Uchiyama, Kentaro Kobayashi, Shiro Watanabe, Takuya Toyonaga, Hisaya Kikuchi, Noriko Oyama-Manabe, Nagara Tamaki
    Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology 24 (1) 329 - 331 1071-3581 2017/02 [Refereed][Not invited]
     
    18F-fluoromisonidazole (FMISO) is a positron emission tomography (PET) tracer that accumulates in hypoxic tissues. We here present a case of suspected cardiac sarcoidosis which was detected with increased FMISO uptake.
  • Shigeru Yamaguchi, Kenji Hirata, Takuya Toyonaga, Kentaro Kobayashi, Yukitomo Ishi, Hiroaki Motegi, Hiroyuki Kobayashi, Tohru Shiga, Nagara Tamaki, Shunsuke Terasaka, Kiyohiro Houkin
    PLOS ONE 11 (12) e0167917  1932-6203 2016/12 [Refereed][Not invited]
     
    BackgroundBevacizumab (BEV), a humanized monoclonal antibody, become a currently important chemotherapeutic option for the patients with recurrent glioma. The aim of this retrospective study is to investigate whether 18 F-Fluoromisonidazole (FMISO) PET have the potential to detect BEV-resistant gliomas in the early-stage.MethodsWe reviewed the FMISO PET and MRI appearances before and 3 to 4 courses after BEV treatment on 18 recurrent glioma patients. FMISO accumulation was assessed by visual inspection and semi-quantitative values which were tumor-to-normal (T/N) ratio and hypoxic volume. MRI responses were evaluated based on RANO (Response Assessment in Neuro-Oncology) criteria. The prognostic analysis was performed in relation to the response assessment by FMISO PET and MRI using overall survival (OS) after BEV application.ResultsAfter BEV application, MRI revealed partial response in 14 of 18 patients (78%), of which 9 patients also demonstrated decreased FMISO accumulation. These 9 patients (50%) were classified as "MRI-FMISO double responder". As for the other 5 patients (28%), FMISO accumulation volumes increased or remained stable after BEV treatment although partial responses were achieved on MRI. Therefore, these cases were classified as "MRI-only responder". The remaining 4 patients (22%) did not show treatment response on FMISO PET or MRI ("non-responder"). MRI-FMISO double responders showed significantly longer OS than that in other groups (median 12.4 vs 5.7 months; P < 0.001), whereas there were no overall survival difference between MRI-only responders and non-responders (median OS, 5.7 and 4.8 months; P = 0.58). Among the pre-treatment clinical factors, high FMISO T/N ratio was a significant prognostic factor of overall survival in these patients under the assessment of Cox proportional hazard model.ConclusionsRecurrent gliomas with decreasing FMISO accumulation after short-term BEV application could derive a survival benefit from BEV treatment. Change in FMISO PET appearance can identify BEV-resistant gliomas in early-stage regardless of MRI findings in a comprehensible way.
  • Shozo Okamoto, Tohru Shiga, Koichi Yasuda, Shiro Watanabe, Kenji Hirata, Ken-ichi Nishijima, Keiichi Magota, Katsuhiko Kasai, Rikiya Onimaru, Kazuhiko Tuchiya, Yuji Kuge, Hiroki Shirato, Nagara Tamaki
    EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 43 (12) 2147 - 2154 1619-7070 2016/11 [Refereed][Not invited]
     
    The purpose of this study was to prospectively investigate reoxygenation in the early phase of fractionated radiotherapy and serial changes of tumoricidal effects associated with intensity-modulated radiation therapy (IMRT) in patients with head and neck cancer (HNC) using F-18 fluoromisonidazole (FMISO) PET and F-18 fluorodeoxyglucose (FDG) PET. Patients with untreated HNC underwent FMISO-PET and FDG-PET studies prospectively. A PET evaluation was conducted before each IMRT (Pre-IMRT), during IMRT (at 30 Gy/15 fr) (Inter-IMRT), and after completion of IMRT (70 Gy/35 fr) (Post-IMRT). FMISO-PET images were scanned by a PET/CT scanner at 4 h after the FMISO injection. We quantitatively analyzed the FMISO-PET images of the primary lesion using the maximum standardized uptake (SUVmax) and tumor-to-muscle ratio (TMR). The hypoxic volume (HV) was calculated as an index of tumor hypoxia, and was defined as the volume when the TMR was aeyen 1.25. Each FDG-PET scan was started 1 h after injection. The SUVmax and metabolic tumor volume (MTV) values obtained by FDG-PET were analyzed. Twenty patients finished the complete PET study protocol. At Pre-IMRT, 19 patients had tumor hypoxia in the primary tumor. In ten patients, the tumor hypoxia disappeared at Inter-IMRT. Another seven patients showed the disappearance of tumor hypoxia at Post-IMRT. Two patients showed tumor hypoxia at Post-IMRT. The FMISO-PET results showed that the reduction rates of both SUVmax and TMR from Pre-IMRT to Inter-IMRT were significantly higher than the corresponding reductions from Inter-IMRT to Post-IMRT (SUVmax: 27 % vs. 10 %, p = 0.025; TMR: 26 % vs. 12 %, p = 0.048). The reduction rate of SUVmax in FDG-PET from Pre-IMRT to Inter-IMRT was similar to that from Inter-IMRT to Post-IMRT (47 % vs. 48 %, p = 0.778). The reduction rate of the HV in FMISO-PET from Pre-IMRT to Inter-IMRT tended to be larger than that from Inter-IMRT to Post-IMRT (63 % vs. 40 %, p = 0.490). Conversely, the reduction rate of the MTV in FDG-PET from Pre-IMRT to Inter-IMRT was lower than that from Inter-IMRT to Post-IMRT (47 % vs. 74 %, p = 0.003). Both the intensity and the volume of tumor hypoxia rapidly decreased in the early phase of radiotherapy, indicating reoxygenation of the tumor hypoxia. In contrast, the FDG uptake declined gradually with the course of radiotherapy, indicating that the tumoricidal effect continues over the entire course of radiation treatment.
  • Noriyuki Fujima, Tomohiro Sakashita, Akihiro Homma, Kenji Hirata, Tohru Shiga, Kohsuke Kudo, Hiroki Shirato
    PLOS ONE 11 (11) e0166236  1932-6203 2016/11 [Refereed][Not invited]
     
    Objective To determine the relationship between tumor glucose metabolism and tumor blood flow (TBF) in head and neck squamous cell carcinoma (HNSCC). Methods We retrospectively analyzed 57 HNSCC patients. Tumor glucose metabolism was assessed by maximum and mean standardized uptake values (SUVmax and SUVmean) obtained by 18 F-fluorodeoxyglucose positron-emission tomography. TBF values were obtained by arterial spin labeling with 3-tesla MRI. The correlations between both SUVs and TBF were assessed in the total series and among patients divided by T-stage (T1-T3 and T4 groups) and tumor location (pharynx/oral cavity and sinonasal cavity groups). Pearson's correlation coefficients were calculated for significant correlations. Results Significant correlations were detected: a negative correlation in the advanced T-stage group (TBF and SUV max: r, -0.61, SUVmean: r, -0.62), a positive correlation in the non-advanced T-stage pharynx/oral cavity group (TBF and SUVmax: r, 0.70, SUVmean: r, 0.73), a negative correlation in the advanced T-stage pharynx/oral cavity group (TBF and SUVmax: r, -0.62, SUVmean: r, -0.65), and a negative correlation in the advanced Tstage sinonasal cavity group (TBF and SUVmax: r, -0.61, SUVmean: r, -0.65). Conclusion Significant correlations between glucose uptake and TBF in HNSCC were revealed by the division of T-stage and tumor location.
  • Shiro Watanabe, Osamu Manabe, Kenji Hirata, Noriko Oyama-Manabe, Naoya Hattori, Yasuka Kikuchi, Kentaro Kobayashi, Takuya Toyonaga, Nagara Tamaki
    BMC cancer 16 635 - 635 2016/08/15 [Refereed][Not invited]
     
    BACKGROUND: Methotrexate-associated lymphoproliferative disorder (MTX-LPD) is a benign lymphoid proliferation or malignant lymphoma in patients who have been treated with MTX. MTX withdrawal and observation for a short period should be considered in the initial management of patients who develop LPD while on MTX therapy. Here we evaluated the diagnostic accuracy and predictive value of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) for MTX-LPD. METHODS: We retrospectively investigated the cases of 15 patients clinically suspected of having MTX-LPD. A total of 324 anatomic regions (207 nodal and 117 extranodal regions) were assessed by (18)F-FDG PET/CT and by multi-detector row CT (MDCT). Each anatomic region was classified as either malignant or benign. The uptake of (18)F-FDG was assessed semi-quantitatively with the standardized uptake value maximum (SUVmax), the whole-body metabolic tumor volume (WBMTV), and the whole-body total lesion glycolysis (WBTLG) in order to investigate predictive factors of spontaneous regression after the withdrawal of MTX. RESULTS: MTX-LPD lesions were observed in 92/324 (28.4 %) regions. (18)F-FDG PET/CT showed 90.2 % sensitivity, 97.4 % specificity, and 95.4 % accuracy, values which were significantly higher than those of MDCT (59.8, 94.8, and 84.9 %, respectively. p < 0.002). After the withdrawal of MTX, 9/15 patients (60.0 %) achieved complete response (CR). The SUVmax, WBMTV and WBTLG values of the CR patients were 9.2 (range 2.8-47.1), 44.3 (range 0-362.6) ml, 181.8 (range 0-2180.9) ml, respectively, which were not significantly different from those of the non-CR patients: 10.6 (range 0-24.9), 15.7 (range 0-250.1) ml, and 97.4 (range 0-1052.1) ml. CONCLUSIONS: Although (18)F-FDG PET/CT was a useful tool to detect MTX-LPD lesions, none of the (18)F-FDG PET parameters before the withdrawal of MTX could be used to predict CR after the withdrawal of MTX.
  • Nagara Tamaki, Kenji Hirata
    INTERNATIONAL JOURNAL OF CLINICAL ONCOLOGY 21 (4) 619 - 625 1341-9625 2016/08 [Refereed][Not invited]
     
    Tumor hypoxia is associated with tumor progression and resistance to various treatments. Noninvasive imaging using positron emission tomography (PET) and F-18-labeled fluoromisonidazole (FMISO) was recently introduced in order to define and quantify tumor hypoxia. The FMISO uptake was closely correlated with pimonidazole immunohistochemistry and hypoxia-inducible factor 1 expression in basic studies. Tumor hypoxia in head and neck cancers and other tumors in a clinical setting may also indicate resistance to radiation and/or chemotherapy. Hypoxic imaging may thus play a new and important role for suitable radiation planning, including dose escalation and dose reduction based on the image findings. Such radiation-dose painting based on the findings of hypoxia may require high-performance PET imaging to provide high target-to-background ratio images and an optimal quantitative parameter to define the hypoxic region. A multicenter prospective study using data from a large number of patients is also warranted to test the clinical value of hypoxic imaging.
  • Tomoka Kitao, Kenji Hirata, Katsumi Shima, Takashi Hayashi, Mitsunori Sekizawa, Toshiki Takei, Wataru Ichimura, Masao Harada, Keishi Kondo, Nagara Tamaki
    BMC CANCER 16 576  1471-2407 2016/08 [Refereed][Not invited]
     
    Background: Volume-based parameters, such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG), on F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) are useful for predicting treatment response in nonsmall cell lung cancer (NSCLC). We aimed to examine intra- and inter-operator reproducibility to measure the MTV and TLG, and to estimate their dependency on the uptake time. Methods: Fifty NSCLC patients underwent preoperative FDG-PET. After an injection of FDG, the whole body was scanned twice: at the early phase (61.4 (+/-) 2.8 min) and delayed phase (117.7 +/- 1.6 min). Two operators independently defined the tumor boundary using three different delineation methods: (1) the absolute SUV threshold method (MTVp and TLG(p); p = 2.0, 2.5, 3.0, 3.5), (2) the fixed% SUVmax threshold method (MTVq% and TLG(q)%; q = 35, 40, 45), and (3) the adaptive region-growing method (MTVARG and TLG(ARG)). Parameters were compared between operators and between phases. Results: Both the intra-and inter-operator reproducibility were high for all parameters using any method (intra-class correlation > 0.99 each). MTV3.0 and MTV3.5 resulted in a significant increase from the early to delayed phase (P < 0.05 for both), whereas MTV2.0 and MTV2.5 neither increased nor decreased (P = n.s.). All of the MTVq% values significantly decreased over time (P < 0.01), whereas MTVARG and TLG with any delineation method increased significantly (P < 0.05). Conclusions: High reproducibility of MTV and TLG was obtained by all of the methods used. MTV2.0 and MTV2.5 were the least sensitive to uptake time, and may be good alternatives when we compare images acquired with different uptake times, although applying constant uptake time is important for volume measurement.
  • Takuya Toyonaga, Kenji Hirata, Shigeru Yamaguchi, Kanako C Hatanaka, Sayaka Yuzawa, Osamu Manabe, Kentaro Kobayashi, Shiro Watanabe, Tohru Shiga, Shunsuke Terasaka, Hiroyuki Kobayashi, Yuji Kuge, Nagara Tamaki
    European journal of nuclear medicine and molecular imaging 43 (8) 1469 - 76 1619-7070 2016/07 [Refereed][Not invited]
     
    PURPOSE: Tumor necrosis is one of the indicators of tumor aggressiveness. (18)F-fluoromisonidazole (FMISO) is the most widely used positron emission tomography (PET) tracer to evaluate severe hypoxia in vivo. Because severe hypoxia causes necrosis, we hypothesized that intratumoral necrosis can be detected by FMISO PET in brain tumors regardless of their histopathology. We applied FMISO PET to various types of brain tumors before tumor resection and evaluated the correlation between histopathological necrosis and FMISO uptake. METHODS: This study included 59 brain tumor patients who underwent FMISO PET/computed tomography before any treatments. According to the pathological diagnosis, the brain tumors were divided into three groups: astrocytomas (group 1), neuroepithelial tumors except for astrocytomas (group 2), and others (group 3). Two experienced neuropathologists evaluated the presence of necrosis in consensus. FMISO uptake in the tumor was evaluated visually and semi-quantitatively using the tumor-to-normal cerebellum ratio (TNR). RESULTS: In visual analyses, 26/27 cases in the FMISO-positive group presented with necrosis, whereas 28/32 cases in the FMISO-negative group did not show necrosis. Mean TNRs with and without necrosis were 3.49 ± 0.97 and 1.43 ± 0.42 (p < 0.00001) in group 1, 2.91 ± 0.83 and 1.44 ± 0.20 (p < 0.005) in group 2, and 2.63 ± 1.16 and 1.35 ± 0.23 (p < 0.05) in group 3, respectively. Using a cut-off value of TNR = 1.67, which was calculated by normal reference regions of interest, we could predict necrosis with sensitivity, specificity, and accuracy of 96.7, 93.1, and 94.9 %, respectively. CONCLUSIONS: FMISO uptake within the lesion indicated the presence of histological micro-necrosis. When we used a TNR of 1.67 as the cut-off value, intratumoral micro-necrosis was sufficiently predictable. Because the presence of necrosis implies a poor prognosis, our results suggest that FMISO PET could provide important information for treatment decisions or surgical strategies of any type of brain tumor.
  • Hirata Kenji, Takeuchi Wataru, Yamaguchi Shigeru, Kobayashi Hiroyuki, Terasaka Shunsuke, Toyonaga Takuya, Watanabe Shiro, Kobayashi Kentaro, Manabe Osamu, Kobashi Keiji, Shiga Tohru, Tamaki Nagara
    JOURNAL OF NUCLEAR MEDICINE 57 0161-5505 2016/05/01 [Refereed][Not invited]
  • Manabe Osamu, Yoshinaga Keiichiro, Ohira Hiroshi, Oyama-Manabe Noriko, Tsujino Ichizo, Hirata Kenji, Kikuchi Hisaya, Nishimura Masaharu, Tamaki Nagara
    JOURNAL OF NUCLEAR MEDICINE 57 0161-5505 2016/05/01 [Refereed][Not invited]
  • Osamu Manabe, Keiichiro Yoshinaga, Hiroshi Ohira, Atsuro Masuda, Takahiro Sato, Ichizo Tsujino, Asuka Yamada, Noriko Oyama-Manabe, Kenji Hirata, Masaharu Nishimura, Nagara Tamaki
    Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology 23 (2) 244 - 52 1071-3581 2016/04 [Refereed][Not invited]
     
    BACKGROUND: (18)F-fluorodeoxyglucose (FDG) PET plays an important role in the detection of cardiac involvement sarcoidosis (CS). However, diffuse left ventricle (LV) wall uptake sometimes makes it difficult to distinguish between positive uptake and physiological uptake. The aims of this study were to evaluate the effects of 18-h fasting with low-carbohydrate diet (LCD) vs a minimum of 6-h fasting preparations on diffuse LV FDG uptake and free fatty acid (FFA) levels in patients with suspected CS. METHODS: Eighty-two patients with suspected CS were divided into 2 preparation protocols: one with a minimum 6-h fast without LCD preparation (group A, n = 58) and the other with a minimum 18-h fast with LCD preparation (group B, n = 24). All patients also received intravenous unfractionated heparin (UFH; 50 IU/kg) before the injection of FDG. RESULTS: Group A showed a higher percentage of diffuse LV uptake than did group B (27.6 vs 0.0%, P = .0041). Group B showed higher FFA levels (1159.1  ±  393.0, 650.5  ±  310.9 μEq/L, P < .0001) than did group A. Patients with diffuse LV uptake (n = 16) showed lower FFA levels than did other patients (n = 66) (432.1  ±  296.1, 888.4  ±  381.4 μEq/L, P < .0001). UFH administration significantly increased FFAs in both groups, even in the patients with diffuse LV FDG uptake. CONCLUSIONS: The 18-h fast with LCD preparation significantly reduced diffuse LV uptake and increased FFA levels. In particular, the FFA level was significantly lower in patients with LV diffuse uptake than in patients without LV diffuse uptake. Acutely increasing plasma FFA through the use of UFH may not have a significant role in reducing physiological LV FDG uptake.
  • Kenji Hirata, Nagara Tamaki
    JOURNAL OF NUCLEAR MEDICINE 57 (2) 169 - 170 0161-5505 2016/02 [Refereed][Not invited]
     
    Gliomas account for 70% of primary brain tumors (1). Among the various types of glioma, glioblastoma is the most aggressive astrocytic tumor, being classified grade IV by the World Health Organization (2). Although CT and MRI are indispensable in providing morphologic information, functional imaging using PET plays an important role in grading tumors, delineating tumor boundaries, monitoring treatment, and discriminating recurrent tumor from treatment-induced changes (3). F-18-FDG is the best-established PET tracer for various malignancies; however, the high, glucose metabolism of the brain prevents accurate evaluation of brain neoplasms using F-18-PDG PET. In addition, although higher-grade gliomas metabolize more glucose than lower-grade gliomas, even glioblastomas sometimes show lower uptake than the surrounding brain tissue, making F-18-FDG PET images difficult to interpret especially in evaluating tumor expansion. In this context, other tracers for brain tumors have been extensively investigated over the past few decades. Among them, amino acid tracers such as C-11-methionine (4,5) and F-18-fluoroethyltyrosine (6,7) have been the most successful, followed by hypoxia imaging agents such as F-18-fluoromisonidazole (8) and nucleic acid analogs such as F-18-fiuorothymidine (9). Now, urokinase-type plasminogen activator receptor (uPAR) has been added to the array of available tracers for imaging.
  • 中咽頭癌に合併し多発骨転移との鑑別が困難であった急性リンパ性白血病の一例
    渡邊 史郎, 真鍋 治, 平田 健司, 菊地 恒矢, 牧野 俊一, 豊永 拓哉, 小林 健太郎, 内山 裕子, 志賀 哲, 加納 里志, 玉木 長良
    核医学 (一社)日本核医学会 53 (1) 507 - 507 0022-7854 2016/02 [Not refereed][Not invited]
  • Maruo Ayaka, Manabe Osamu, Yoshinaga Keiichiro, Naya Masanao, Tomiyama Yuuki, Oyama-Manabe Noriko, Hirata Kenji, Magota Keiichi, Tsutsui Hiroyuki, Katoh Chietsugu, Tamaki Nagara
    Annals of Nuclear Cardiology 日本心臓核医学会 2 (1) 30 - 37 2016 
    Purpose: The quantification of coronary flow reserve (CFR) calculated as the ratio of the myocardial blood flow (MBF) during adenosine triphosphate (ATP) stress to MBF at rest is a useful method for evaluating the functional severity of coronary artery disease (CAD) using 15O-H2O positron emission tomography (PET). The shorter acquisition time may reduce dyspnea and other side effects of ATP stress and may also reduce the effect of body movements during data acquisition. However, the impact of the shorter data acquisition time on the accuracy of MBF quantification has not been studied. In this retrospective study, we evaluated the accuracy of the MBF and CFR values obtained with shorter scan times using 15O-H2O PET.
    Methods: Thirty patients suspected of having CAD (22 males, 8 females; age 56.5±8.8 yrs) and 17 healthy controls (17 males; age 27.7±6.2 yrs) underwent PET during rest and PET with ATP stress dynamic 15O-H2O. The MBF was estimated with a one-tissue compartment model analysis. MBF and CFR values were calculated using the first 2-min and 3-min PET data of 15O-H2O as shorter data acquisitions. These data were compared to the standard 6-min PET acquisition data.
    Results: With the use of the 3-min data, the regions of interest (ROIs) in the left ventricular (LV) chamber and myocardium could be set for all of the subjects. The intraclass correlation coefficients (ICCs) between the 3-min data and 6-min data of the rest MBF, stress MBF and CFR were 0.869, 0.870, and 0.819 in the patients, and 0.912, 0.910, and 0.930 in the controls. The 3-min CFR data showed a significant difference between the patients and controls (2.22±1.02 vs. 4.02±1.50, p<0.01), as did the 6-min data (2.19±0.92 vs. 4.16±1.39, p<0.01). However, the CFR based on 2-min data did not show a significant difference (1.96±1.66 vs. 2.73±1.03, p=0.088). Using a receiver operating characteristic (ROC) analysis, we observed that both the 3-min and 6-min CFR data could be used to separate the CAD patients and controls.
    Conclusions: A 3-min, but not 2-min, scan with 15O-H2O PET can be used for the quantitative evaluation of MBF and CFR.
  • S. Kitamura, H. Hata, Y. Inamura, K. Imafuku, T. Sakashita, K. Hirata, H. Shimizu
    British Journal of Dermatology 173 (5) 1263 - 1265 1365-2133 2015/11/01 [Refereed][Not invited]
     
    Primary mucinous carcinoma of the skin (PMCS) is a rare cutaneous malignant neoplasm its regional node metastasis is also rare. Currently, positron emission tomography-computed tomography (PET-CT) is known to be a useful tool to search for early metastatic lesions in various carcinomas. However, PET-CT is not always specific for head and neck lesions because of physiological uptake in the brain, palatine tonsil, salivary gland, thyroid etc. Herein we present two cases of head and neck PMCS in which metastasis was diagnosed accurately by PET-CT. In these cases, nodal uptake of fluorodeoxy-d-glucose (FDG) histopathologically proved PMCS metastasis, verifying the utility of PET-CT in detail. A surgeon was involved in the verification to compare the histopathological manifestations with the imaging results. Histopathologically, two of 13 nodes were positive in case 1, and one of 41 nodes was positive in case 2. These positive nodes were completely in accordance with the FDG uptake findings with no false negative findings. In treating PMCS on head and neck lesions, PET-CT may be useful in the preoperative assessment when planning the extent of resection. What's already known about this topic? Primary mucinous carcinoma of the skin (PMCS) is a rare cutaneous malignant neoplasm. Positron emission tomography-computed tomography (PET-CT) is known to be a useful tool to search for early metastatic lesions in various carcinomas however, its applicability for detecting PMCS metastasis is unknown. What does this study add? This is the first study to address the applicability of PET-CT for detecting PMCS metastasis on the head and neck area, and PMCS in which metastasis is diagnosed accurately by PET-CT.
  • Yuuki Tomiyama, Osamu Manabe, Noriko Oyama-Manabe, Masanao Naya, Hiroyuki Sugimori, Kenji Hirata, Yuki Mori, Hiroyuki Tsutsui, Kohsuke Kudo, Nagara Tamaki, Chietsugu Katoh
    Journal of magnetic resonance imaging : JMRI 42 (3) 754 - 62 1053-1807 2015/09 [Refereed][Not invited]
     
    BACKGROUND: To develop and validate a method for quantifying myocardial blood flow (MBF) using dynamic perfusion magnetic resonance imaging (MBFMRI ) at 3.0 Tesla (T) and compare the findings with those of (15) O-water positron emission tomography (MBFPET ). METHODS: Twenty healthy male volunteers underwent magnetic resonance imaging (MRI) and (15) O-water positron emission tomography (PET) at rest and during adenosine triphosphate infusion. The single-tissue compartment model was used to estimate the inflow rate constant (K1). We estimated the extraction fraction of Gd-DTPA using K1 and MBF values obtained from (15) O-water PET for the first 10 subjects. For validation, we calculated MBFMRI values for the remaining 10 subjects and compared them with the MBFPET values. In addition, we compared MBFMRI values of 10 patients with coronary artery disease with those of healthy subjects. RESULTS: The mean resting and stress MBFMRI values were 0.76 ± 0.10 and 3.04 ± 0.82 mL/min/g, respectively, and showed excellent correlation with the mean MBFPET values (r = 0.96, P < 0.01). The mean stress MBFMRI value was significantly lower for the patients (1.92 ± 0.37) than for the healthy subjects (P < 0.001). CONCLUSION: The use of dynamic perfusion MRI at 3T is useful for estimating MBF and can be applied for patients with coronary artery disease.
  • Kenji Hirata, Naoya Hattori, Wataru Takeuchi, Tohru Shiga, Yuichi Morimoto, Kikuo Umegaki, Kentaro Kobayashi, Osamu Manabe, Shozo Okamoto, Nagara Tamaki
    Journal of nuclear medicine : official publication, Society of Nuclear Medicine 56 (8) 1206 - 11 0161-5505 2015/08 [Refereed][Not invited]
     
    UNLABELLED: The red nucleus (RN) is a pair of small gray matter structures located in the midbrain and involved in muscle movement and cognitive functions. This retrospective study aimed to investigate the metabolism of human RN and its correlation to other brain regions. METHODS: We developed a high-resolution semiconductor PET system to image small brain structures. Twenty patients without neurologic disorders underwent whole-brain scanning after injection of 400 MBq of (18)F-FDG. The individual brain (18)F-FDG PET images were spatially normalized to generate a surface projection map using a 3-dimensional stereotactic surface projection technique. The correlation between the RN and each voxel on the cerebral and cerebellar cortices was estimated with Pearson product-moment correlation analysis. RESULTS: Both right and left RNs were visualized with higher uptake than that in the background midbrain. The maximum standardized uptake values of RN were 7.64 ± 1.92; these were higher than the values for the dentate nucleus but lower than those for the caudate nucleus, putamen, and thalamus. The voxel-by-voxel analysis demonstrated that the right RN was correlated more with ipsilateral association cortices than contralateral cortices, whereas the left RN was equally correlated with ipsilateral and contralateral cortices. The left RN showed a stronger correlation with the motor cortices and cerebellum than the right RN did. CONCLUSION: Although nonspecific background activity around RNs might have influenced the correlation patterns, these metabolic relationships suggested that RN cooperates with association cortices and limbic areas to conduct higher brain functions.
  • Primary mucinous cell carcinoma of the skinのリンパ節転移に関するPET-CT所見の検討
    北村 真也, 秦 洋郎, 稲村 有香, 今福 恵輔, 坂下 智博, 平田 健司, 清水 宏
    日本皮膚科学会雑誌 (公社)日本皮膚科学会 125 (8) 1601 - 1602 0021-499X 2015/07
  • Yae Harada, Kenji Hirata, Naoki Nakayama, Shigeru Yamaguchi, Michiharu Yoshida, Shunsuke Onodera, Osamu Manabe, Tohru Shiga, Satoshi Terae, Hiroki Shirato, Nagara Tamaki
    Acta radiologica open 4 (6) 2058460115584112 - 2058460115584112 2015/06 [Refereed][Not invited]
     
    A 55-year-old woman underwent radiosurgery for a left cerebral hemisphere arteriovenous malformation (AVM) and developed radiation-induced necrosis causing a massive edema in the surrounding brain tissues. Despite various therapies, the edema expanded to the ipsilateral hemisphere and induced neurological symptoms. The radiation-induced necrotic lesion was surgically removed 4 years after radiosurgery. While the preoperative FDG PET revealed severe hypometabolism in the left cerebrum, the necrotomy significantly ameliorated the brain edema, glucose metabolism (postoperative FDG PET), and symptoms. This case indicates that radiation necrosis-induced neurological deficits may be associated with brain edema and hypometabolism, which could be reversed by appropriate necrotomy.
  • Kentaro Kobayashi, Kenji Hirata, Shigeru Yamaguchi, Osamu Manabe, Shunsuke Terasaka, Hiroyuki Kobayashi, Tohru Shiga, Naoya Hattori, Shinya Tanaka, Yuji Kuge, Nagara Tamaki
    European journal of nuclear medicine and molecular imaging 42 (7) 1071 - 80 1619-7070 2015/06 [Refereed][Not invited]
     
    PURPOSE: (11)C-methionine (MET) PET is an established diagnostic tool for glioma. Studies have suggested that MET uptake intensity in the tumor is a useful index for predicting patient outcome. Because MET uptake is known to reflect tumor expansion more accurately than MRI, we aimed to elucidate the association between volume-based tumor measurements and patient prognosis. METHODS: The study population comprised 52 patients with newly diagnosed glioma who underwent PET scanning 20 min after injection of 370 MBq MET. The tumor was contoured using a threshold of 1.3 times the activity of the contralateral normal cortex. Metabolic tumor volume (MTV) was defined as the total volume within the boundary. Total lesion methionine uptake (TLMU) was defined as MTV times the mean standardized uptake value (SUVmean) within the boundary. The tumor-to-normal ratio (TNR), calculated as the maximum standardized uptake value (SUVmax) divided by the contralateral reference value, was also recorded. All patients underwent surgery (biopsy or tumor resection) targeting the tissue with high MET uptake. The Kaplan-Meier method was used to estimate the predictive value of each measurement. RESULTS: Grade II tumor was diagnosed in 12 patients (3 diffuse astrocytoma, 2 oligodendroglioma, and 7 oligoastrocytoma), grade III in 18 patients (8 anaplastic astrocytoma, 6 anaplastic oligodendroglioma, and 4 anaplastic oligoastrocytoma), and grade IV in 22 patients (all glioblastoma). TNR, MTV and TLMU were 3.1 ± 1.2, 51.6 ± 49.9 ml and 147.7 ± 153.3 ml, respectively. None of the three measurements was able to categorize the glioma patients in terms of survival when all patients were analyzed. However, when only patients with astrocytic tumor (N = 33) were analyzed (i.e., when those with oligodendroglial components were excluded), MTV and TLMU successfully predicted patient outcome with higher values associated with a poorer prognosis (P < 0.05 and P < 0.01, respectively), while the predictive ability of TNR did not reach statistical significance (P = NS). CONCLUSION: MTV and TLMU may be useful for predicting outcome in patients with astrocytic tumor.
  • Osamu Manabe, Naoya Hattori, Shigeru Yamaguchi, Kenji Hirata, Kentaro Kobayashi, Shunsuke Terasaka, Hiroyuki Kobayashi, Hiroaki Motegi, Tohru Shiga, Keiichi Magota, Noriko Oyama-Manabe, Ken-ichi Nishijima, Yuji Kuge, Nagara Tamaki
    European journal of nuclear medicine and molecular imaging 42 (6) 896 - 904 1619-7070 2015/05 [Refereed][Not invited]
     
    PURPOSE: Previous radiological investigations have generally shown the superiority of metabolic imaging in distinguishing high-grade from low-grade glioma, but the presence of an oligodendroglial component may affect the diagnostic accuracy. We investigated the diagnostic accuracy of PET imaging using (11)C-methionine (MET) and (18)F-fluorodeoxyglucose (FDG) in distinguishing high-grade from low-grade glioma, in correlation with the oligodendroglial component. METHODS: The study population comprised adult patients who underwent preoperative PET imaging using both MET and FDG within 1 week and successful excision of the tumour tissue, which confirmed WHO grade II-IV glioma. We examined the tumour metabolic activity in terms of lesion-to-normal uptake ratios (L/N ratio) in both MET PET and FDG PET images. We assessed the correlation between the imaging results and the histological findings to determine the diagnostic accuracy of receiver operating characteristics (ROC) analysis in detecting high-grade tumours. RESULTS: We studied 46 patients with glioma (13 low-grade and 33 high-grade), including 26 with an oligodendroglial components. The L/N ratios of the PET images showed significantly higher metabolic activities in high-grade gliomas than in low-grade gliomas for both MET (4.29 ± 1.22 and 2.36 ± 0.72, respectively; p < 0.0001) and FDG (1.72 ± 0.91 and 0.77 ± 0.26, respectively; p = 0.0007) images, although significant overlaps in L/N ratio were observed between high-grade and low-grade gliomas. Excluding the 26 patents with an oligodendroglial component improved the separation for both MET (4.62 ± 1.14 vs. 2.16 ± 0.63; p < 0.001) and FDG (1.76 ± 0.87 vs. 0.71 ± 0.14; p < 0.05) images. The ROC analyses demonstrated the clinical utility of the metabolic radiotracers in distinguishing high-grade from low-grade gliomas, showing similar AUC values for MET (0.91) and FDG (0.92). Excluding the 26 patents with an oligodendroglial component also further improved the diagnostic accuracy for both MET (AUC 0.98), and FDG (AUC 1.00) images. The metabolic radiotracers were significantly correlated with the MIB-1 labelling index (R = 0.52, p < 0.05 for MET; R = 0.52, p < 0.05, for FDG) only in gliomas without an oligodendroglial component. CONCLUSION: For better characterization of gliomas and for risk assessment, the results of metabolic PET imaging should be revised after obtaining the pathological report, because oligodendroglial differentiation may positively influence the substrate metabolism and thus complicated the preoperative evaluation.
  • Satoko Sudo, Naoya Hattori, Osamu Manabe, Fumi Kato, Rie Mimura, Keiichi Magota, Hiroyuki Sugimori, Kenji Hirata, Noriaki Sakuragi, Nagara Tamaki
    European journal of nuclear medicine and molecular imaging 42 (5) 676 - 84 1619-7070 2015/04 [Refereed][Not invited]
     
    PURPOSE: The staging of endometrial cancer requires surgery which carries the risk of morbidity. FDG PET/CT combined with anatomical imaging may reduce the number of unnecessary lymphadenectomies by demonstrating the risk of extrapelvic infiltration. The purpose of this study was to optimize FDG PET/CT diagnostic criteria for risk assessment in endometrial cancer after first-line risk triage with MRI. METHODS: The study population comprised 37 patients who underwent curative surgery for the treatment of endometrial cancer. First, the risk of extrapelvic infiltration was triaged using MRI. Second, multiple glucose metabolic profiles of the primary lesion were assessed with FDG PET/CT, and these were correlated with the histopathological risk of extrapelvic infiltration including lymphovascular space invasion (LVSI) and high-grade malignancy (grades 2 and 3). The results of histological correlation were used to adjust FDG PET/CT diagnostic criteria. RESULTS: Presurgical assessment using MRI was positive for deep (>50 %) myometrial invasion in 17 patients. The optimal FDG PET/CT diagnostic criteria vary depending on the results of MRI. Specifically, SUVmax (≥16.0) was used to indicate LVSI risk with an overall diagnostic accuracy of 88.2 % in patients with MRI findings showing myometrial invasion. High-grade malignancy did not correlate with any of metabolic profiles in this patient group. In the remaining patients without myometrial invasion, lesion glycolysis (LG) or metabolic volume were better indicators of LVSI than SUVmax with the same diagnostic accuracy of 80.0 %. In addition, LG (≥26.9) predicted high-grade malignancy with an accuracy of 72.2 %. Using the optimized cut-off criteria for LVSI, glucose metabolic profiling of primary lesions correctly predicted lymph node metastasis with an accuracy of 73.0 %, which was comparable with the accuracy of visual assessment for lymph node metastasis using MRI and FDG PET/CT. CONCLUSION: FDG PET/CT diagnostic criteria may need adjustment based on the anatomical information provided by MRI. The optimized criteria can predict the risk of pathology-proven LVSI correctly in 83.8 % of patients before surgery, and thus would improve presurgical treatment planning.
  • Shigeru Yamaguchi, Kenji Hirata, Sadahiro Kaneko, Hiroyuki Kobayashi, Tohru Shiga, Kentaro Kobayashi, Rikiya Onimaru, Hiroki Shirato, Nagara Tamaki, Shunsuke Terasaka, Kiyohiro Houkin
    ACTA NEUROCHIRURGICA 157 (2) 187 - 194 0001-6268 2015/02 [Refereed][Not invited]
     
    Although histological diagnosis is indispensable in treating primary central nervous system lymphoma (PCNSL), we sometimes face an intractable situation in which tissue can be obtained only from a deep-seated brain lesion. In place of a histological diagnosis, the diagnostic adequacy of the combined use of 18 F-FDG PET and corticosteroid administration for PCNSL located in a deep-seated brain structure is reported.Patients with a deep-seated tumor were treated as having PCNSL without histological confirmation, based on the following criteria: (1) there was no evidence of systemic malignancy; (2) the tumor showed an extremely high FDG uptake relative to normal gray matter on pretreatment 18 F-FDG PET; (3) the tumor decreased in size 1 week after diagnostic therapy by corticosteroid administration on contrast-enhanced T1-weighted magnetic resonance imaging (MRI). FDG uptake of the lesion was evaluated by the maximum of standardized uptake values (SUVmax) and tumor-to-normal ratio of the SUV (T/N ratio). The extent of the tumor reduction was calculated by volumetric analysis for the treatment response to corticosteroid administration.Ten patients (4 males and 6 females) matched these criteria. On pretreatment 18 F-FDG PET, mean SUVmax in the tumor was 24.8 (8.75-60.75), and mean T/N ratio was 3.24 (2.17-5.12). The extent of tumor volume reduction was shown to be 21 to 68 % 1 week after diagnostic therapy by corticosteroids. Mean total dose and duration of corticosteroids were 719 mg as prednisolone and 6.5 days, respectively. Nine patients achieved complete response and one patient achieved partial response on MRI after standard treatment for PCNSL with high-dose methotrexate and/or whole-brain irradiation.Although the value of biopsy is universal, combining 18 F-FDG PET and corticosteroid administration is an important alternative method that may lead to the diagnosis of deep-seated PCNSLs in cases with intractable histopathological confirmations.
  • Kentaro Kobayashi, Naoya Hattori, Osamu Manabe, Kenji Hirata, Keiichi Magota, Tsuyoshi Shimamura, Nagara Tamaki
    Annals of transplantation 20 51 - 8 1425-9524 2015/01/26 [Refereed][Not invited]
     
    BACKGROUND: Living liver donation is associated with size-dependent complications. The resectable size and its safety margin should be defined for the safety of donors. The purpose of the present study was to determine if the current partial hepatectomies are done under the safety margin of the resectable size, by measuring asialoglycoprotein receptor (ASGPR) function of donor's remnant liver. MATERIAL AND METHODS: Seventy-four living donors (age 35±11 years) underwent Technetium-99m-diethylenetriaminepentaacetic acid-galactosyl-human serum albumin (Tc-99m GSA) scintigraphy at postoperative week 1. We evaluated the scintigraphic results using established parameters of GSA uptake (LHL15) and its clearance from the blood pool (HH15). Based on the literature, we consider HH15 <0.55 to indicate normal ASGPR function, and 0.55£ HH15 <0.65 to indicate mild impairment. In terms of the hepatic uptake, we consider LHL15>0.93 to indicate normal ASGPR function, and 0.87< LHL15 £0.93 to indicate mild impairment. RESULTS: The average resected size was 337±170 mL, corresponding to 28±12% of the original donor's whole liver volume. No donors showed 0.65≤ HH15 or LHL15 <0.87, suggesting moderate or severely impaired ASGPR function. However, larger resection size (35-53%) was positively associated with higher HH15 values (R=0.53, p<0.001). In the range of HH15 (0.35-0.64) among present donors, higher HH15 values did not affect the regeneration volume (R=0.03, p=NS). CONCLUSIONS: Larger partial resection (≥35% of the original liver volume) may impair postsurgical ASGPR function, but smaller resection (<35%) was considered to be under the safety margin of the hepatectomy. Although mildly impaired postsurgical ASGPR function did not indicate poor prognosis, careful attention may be required for donors undergoing larger (³35%) partial resection.
  • Yuki Mori, Osamu Manabe, Masanao Naya, Yuuki Tomiyama, Keiichiro Yoshinaga, Keiichi Magota, Noriko Oyama-Manabe, Kenji Hirata, Hiroyuki Tsutsui, Nagara Tamaki, Chietsugu Katoh
    Annals of nuclear medicine 29 (1) 15 - 20 0914-7187 2015/01 [Refereed][Not invited]
     
    OBJECTIVE: (11)C-acetate has been applied for evaluation of myocardial oxidative metabolism and can simultaneously estimate myocardial blood flow (MBF). We developed a new method using two-parameter spillover correction to estimate regional MBF (rMBF) with (11)C-acetate PET in reference to MBF derived from (15)O-H2O PET. The usefulness of our new approach was evaluated compared to the conventional method using one-parameter spillover correction. METHODS: Sixty-three subjects were examined with (11)C-acetate and (15)O-H2O dynamic PET at rest. Inflow rate of (11)C-acetate (K1) was compared with MBF derived from (15)O-H2O PET. For the derivation, the relationship between K1 and MBF from (15)O-H2O was linked by the Renkin-Crone model in 20 subjects as a pilot group. One-parameter and two-parameter corrections were applied to suppress the spillover between left ventricular (LV) wall and LV cavity. Validation was set using the other 43 subjects' data. Finally, rMBFs were calculated using relational expression derived from the pilot-group data. RESULTS: The relationship between K1 and MBF derived from (15)O-H2O PET was approximated as K1 = [1-0.764 × exp(-1.001/MBF)] MBF from the pilot data using the two-parameter method. In the validation set, the correlation coefficient between rMBF from (11)C-acetate and (15)O-H2O demonstrated a significantly higher relationship with the two-parameter spillover correction method than the one-parameter spillover correction method (r = 0.730, 0.592, respectively, p < 0.05). CONCLUSION: In (11)C-acetate PET study, the new two-parameter spillover correction method dedicated more accurate and robust myocardial blood flow than the conventional one-parameter method.
  • Satoshi Kuroda, Daina Kashiwazaki, Kenji Hirata, Tohru Shiga, Kiyohiro Houkin, Nagara Tamaki
    STROKE 45 (9) 2717 - 2721 0039-2499 2014/09 [Refereed][Not invited]
     
    Background and Purpose-This prospective study was aimed to evaluate the effects of surgical revascularization on cerebral oxygen metabolism in moyamoya disease. Methods-This study included totally 69 hemispheres of 42 patients who underwent superficial temporal artery to middle cerebral artery anastomosis and indirect bypass for moyamoya disease between 2000 and 2011. There were 12 children and 30 adults. MRI and O-15-gas positron emission tomography were performed before and 3 to 4 months after surgery. Hemodynamic and metabolic parameters were precisely quantified and statistically analyzed. Results-Preoperative positron emission tomographic scans revealed that cerebral blood flow was decreased, cerebral blood volume was increased, and cerebral metabolic rate for oxygen was decreased in both pediatric and adult patients. Cerebral metabolic rate for oxygen reduction was observed in approximate to 80% of pediatric (16/21; 76%) and adult hemispheres (38/48; 79%). Surgical revascularization resolved hemodynamic compromise in all operated hemispheres. Cerebral metabolic rate for oxygen significantly improved in pediatric patients without parenchymal lesions (n=8), but not those with parenchymal lesions (n=8). Multivariate analysis revealed that cerebral metabolic rate for oxygen significantly improved in younger adult patients without parenchymal lesions (P=0.0264; odds ratio, 0.88; 95% confidence interval, 0.79-0.99). Conclusions-Cerebral oxygen metabolism is significantly depressed in approximate to 80% of the involved hemispheres of moyamoya disease and improves in pediatric and younger adult patients without parenchymal lesions after bypass surgery. Cerebral oxygen metabolism may be reversibly depressed in response to cerebral ischemia in them although the underlying mechanisms are still unclear.
  • Hirata K, Fujima N, Mizumachi T, Bandarchi B, Roesler JM
    Acta radiologica short reports 3 (8) 2047981614549497 - 2047981614549497 2014/09 [Refereed][Not invited]
     
    A 34-year-old man found a mildly tender preauricular mass. Ultrasonography revealed an anechoic mass in the superficial lobe of the parotid gland. Magnetic resonance imaging showed thin ring-like contrast enhancement and homogenously high intensity on T2-weighted images. The mass was resected due to its rapid growth. The cystic lesion contained keratine-like material and a stratified squamous epithelium without granular layers, which was consistent with keratocystoma.
  • Shigeru Yamaguchi, Kenji Hirata, Hiroyuki Kobayashi, Tohru Shiga, Osamu Manabe, Kentaro Kobayashi, Hiroaki Motegi, Shunsuke Terasaka, Kiyohiro Houkin
    Annals of nuclear medicine 28 (7) 603 - 9 0914-7187 2014/08 [Refereed][Not invited]
     
    OBJECTIVE: (18)F-FDG PET has become one of the most important methods for studying malignant lymphoma, but its diagnostic role for primary central nervous system lymphoma (PCNSL) has not been established. The aim of this study was to determine the appropriate cut-off values of FDG uptake and to investigate how corticosteroid administration influences PCNSL. METHODS: We retrospectively reviewed 82 patients with contrast-enhanced brain tumors who underwent an FDG PET scan at onset, including 19 PCNSLs. FDG uptake of the lesion was assessed by the maximum standardized uptake value (SUVmax) and the ratio of tumor to normal contralateral cortex activity (T/N ratio). Receiver operating characteristic (ROC) curves were generated from the SUVmax and T/N ratios. To investigate the influence of corticosteroid application before a FDG PET scan, we evaluated the association between the FDG uptake of the lesion and the cumulative dose of corticosteroid administration on 13 PCNSL patients who had received steroid treatment before an FDG PET examination. RESULTS: The mean FDG SUVmax and T/N ratio of PCNSLs were 22.6 and 2.79, respectively, and these values were significantly higher than those of the other malignant brain tumors. ROC analysis indicated that the evaluation of FDG uptake using the T/N ratio was more reliable than the SUVmax with respect to the differential diagnosis. When PCNSL patients went without steroid application before FDG PET, the accuracy of the T/N ratio with a cut-off point of 2.0 was 91.1%, the sensitivity was 94.7%, and the specificity was 87.3%. Although there are no significant differences in the FDG T/N ratio for PCNSL patients with or without steroid treatment, a negative correlation was found between the T/N ratio and cumulative dose of corticosteroid before PET study (r = -0.71, p = 0.032). CONCLUSIONS: We concluded that the T/N ratio was superior to SUVmax for FDG uptake assessment as for distinguishing PCNSLs from other malignant brain tumors; the appropriate T/N ratio cut-off point was 2.0. In addition, FDG uptake could be influenced by cumulative doses of corticosteroid before a PET scan, and thus this fact should be taken into consideration when evaluating FDG PET for PCNSL diagnosis.
  • Naoki Kubo, Kenji Hirata, Kazuki Matsuzaki, Yuichi Morimoto, Wataru Takeuchi, Naoya Hattori, Tohru Shiga, Yuji Kuge, Nagara Tamaki
    NUCLEAR MEDICINE COMMUNICATIONS 35 (6) 677 - 682 0143-3636 2014/06 [Refereed][Not invited]
     
    Objective PET using semiconductor detectors provides high-quality images of the human brain because of its high spatial resolution. To quantitatively evaluate the delineation of image details in clinical PET images, we used normalized mutual information (NMI) to quantify the similarity with images obtained through MRI. NMI is used to evaluate image quality by determining similarity with a reference image. The aim of this study was to evaluate quantitatively the delineation of image details provided by semiconductor PET. Materials and methods To quantitatively evaluate anatomical delineation in clinical PET images, MRI scans of patients were used as T1-weighted images. [F-18]-fluorodeoxyglucose (F-18-FDG) PET brain images were obtained from six patients using (a) a Hitachi semiconductor PET scanner and (b) a ECAT HR+ scintillator PET scanner. The NMI calculated from the semiconductor PET and MRI was denoted by NMIsemic, whereas the NMI calculated from conventional scintillator PET and MRI was denoted by NMIconve. The higher the value of NMI, the greater the similarity to MRI. Results NMIsemic ranged from 1.22 to 1.29, whereas NMIconve ranged from 1.13 to 1.18 (P < 0.05). Furthermore, all the NMI values of the semiconductor PET were higher than those of the conventional scintillator PET. Conclusion Utilizing NMI, we quantitatively evaluated the delineation of image details in clinical PET images. The results reveal that semiconductor PET has superior anatomical delineation and physical performance compared with conventional scintillator PET. This improved delineation of image details makes semiconductor PET promising for clinical applications.
  • Satoshi Kuroda, Masahito Kawabori, Kenji Hirata, Tohru Shiga, Daina Kashiwazaki, Kiyohiro Houkin, Nagara Tamaki
    ACTA NEUROCHIRURGICA 156 (1) 77 - 83 0001-6268 2014/01 [Refereed][Not invited]
     
    Even after the recent randomized clinical trials JET and COSS, it is still unclear that impaired cerebrovascular reactivity (CVR) to acetazolamide and oxygen extraction fraction (OEF) can identify the candidates for superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis. This prospective study was aimed to evaluate the benefits of STA-MCA "double" anastomosis on long-term outcome in patients with reduced cerebral blood flow (CBF) and CVR (Type 3 ischemia) and elevated OEF attributable to occlusive carotid diseases. This study included 49 patients with reduced CBF and CVR on SPECT in the ipsilateral MCA area. Using O-15-gas PET, OEF was also measured in all patients. STA-MCA double anastomosis was recommended to the patients with Type 3 and elevated OEF. Those with Type 3 but normal OEF were medically treated. Of 36 patients with Type 3 and elevated OEF, 25 consented to surgery. No perioperative morbidity or mortality were noted. The other 11 patients with Type 3 and elevated OEF were medically treated. Annual incidence of ipsilateral stroke was 0.7 % and 6.5 % in surgically and medically treated patients with Type 3 and elevated OEF, respectively (P = 0.0188). None of patients with Type 3 but normal OEF developed ipsilateral stroke during follow-up periods. STA-MCA "double" anastomosis significantly decreased OEF. STA-MCA "double" anastomosis may still have the potential to reduce the risk of recurrent ipsilateral stroke in hemodynamically compromised patients. Further studies would be essential to advance diagnosis, surgical procedures, and perioperative managements to bring out maximal effects of bypass surgery.
  • Kenji Hirata, Kentaro Kobayashi, Koon-Pong Wong, Osamu Manabe, Andrew Surmak, Nagara Tamaki, Sung-Cheng Huang
    PloS one 9 (8) e105682  2014 [Refereed][Not invited]
     
    BACKGROUND: 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)-computed tomography (CT) has been an essential modality in oncology. We propose a semi-automated algorithm to objectively determine liver standardized uptake value (SUV), which is used as a threshold for tumor delineation. METHODS: A large spherical volume of interest (VOI) was placed manually to roughly enclose the right lobe (RL) of the liver. For each voxel in this VOI, a coefficient of variation of voxel values (CVv) was calculated for neighboring voxels within a radius of d/2. The voxel with the minimum CVv was then selected, where a 30-mm spherical VOI was placed at that voxel in accordance with PERCIST criteria. Two nuclear medicine physicians independently defined 30-mm VOIs manually on 124 studies in 62 patients to generate the standard values, against which the results from the new method were compared. RESULTS: The semi-automated method was successful in determining the liver SUV that was consistent between the two physicians in all the studies (d = 80 mm). The liver SUV threshold (mean +3 SD within 30-mm VOI) determined by the new semi-automated method (3.12±0.61) was not statistically different from those determined by the manual method (Physician-1: 3.14±0.58, Physician-2: 3.15±0.58). The semi-automated method produced tumor volumes that were not statistically different from those by experts' manual operation. Furthermore, the volume change in the two sequential studies had no statistical difference between semi-automated and manual methods. CONCLUSIONS: Our semi-automated method could define the liver SUV robustly as the threshold value used for tumor volume measurements according to PERCIST. The method could avoid possible subjective bias of manual liver VOI placement and is thus expected to improve clinical performance of volume-based parameters for prediction of cancer treatment response.
  • Masahito Kawabori, Satoshi Kuroda, Naoki Nakayama, Kenji Hirata, Toru Shiga, Kiyohiro Houkin, Nagara Tamaki
    WORLD NEUROSURGERY 80 (5) 612 - 619 1878-8750 2013/11 [Refereed][Not invited]
     
    BACKGROUND: Headache is one of the major clinical presentations in pediatric Moyamoya disease. However, the clinical features and underlying mechanisms are not fully understood. This study aimed to clarify the clinical feature of headache in pediatric Moyamoya disease and the effect of surgical revascularization. METHODS: This study included 29 pediatric patients who underwent superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and indirect bypass for Moyamoya disease. Their medical records were precisely evaluated to identify the clinical features of their headache. The findings on magnetic resonance imaging, positron emission tomography, and single-photon emission computed tomography also were analyzed. RESULTS: Preoperative headache was documented in 11 (38%) of 29 patients. The majority of them complained of severe headache in the frontal or temporal region in the morning. Headache was significantly related to more advanced disease stage and to the decreases in cerebral blood flow and its reactivity to acetazolamide. Surgical revascularization completely resolved headache in all 11 patients. CONCLUSIONS: These findings strongly suggest that disturbed cerebral hemodynamics may play key roles in developing severe headache in pediatric Moyamoya disease. STA-MCA anastomosis and encephalo-duro-myo-arterio-pericranial synangiosis may be effective procedures to rapidly resolve headache by widely supplying collateral blood flow to the operated hemispheres.
  • Hiroyuki Kobayashi, Kenji Hirata, Shigeru Yamaguchi, Shunsuke Terasaka, Tohru Shiga, Kiyohiro Houkin
    NEUROLOGIA MEDICO-CHIRURGICA 53 (11) 773 - 778 0470-8105 2013/11 [Refereed][Not invited]
     
    Glioma is one of the most common brain tumors in adults. Its diagnosis and management have been determined by histological classifications. It is difficult to establish new paradigms because the pathology has matured and a great deal of knowledge has accumulated. On the other hand, we understand that there are limitations to this gold-standard because of the heterogeneity of glioma. Thus, it is necessary to find new criteria independent of conventional morphological diagnosis. Molecular imaging such as positron emission tomography (PET) is one of the most promising approaches to this challenge. PET provides live information of metabolism through the behavior of single molecules. The advantage of PET is that its noninvasive analysis does not require tissue sample, therefore examination can be performed repeatedly. This is very useful for capturing changes in the biological nature of tumor without biopsy. In the present clinical practice for glioma, F-18-fluorodeoxyglucose (FDG) PET is the most common tracer for predicting prognosis and differentiating other malignant brain tumors. Amino acid tracers such as C-11-methionine (MET) are the most useful for detecting distribution of glioma, including low-grade. Tracers to image hypoxia are under investigation for potential clinical use, and recently, F-18-fluoromisonidazole (FMISO) has been suggested as an effective tracer to distinguish glioblastoma multiforme from others.
  • Songji Zhao, Yuji Kuge, Yan Zhao, Satoshi Takeuchi, Kenji Hirata, Toshiki Takei, Tohru Shiga, Hirotoshi Dosaka-Akita, Nagara Tamaki
    BMC CANCER 13 525  1471-2407 2013/11 [Refereed][Not invited]
     
    Background: The purpose of this study was to evaluate whether early changes in 3'-deoxy-3'-H-3-fluorothymidine (H-3-FLT) uptake can reflect the antiproliferative effect of gefitinib in a human tumor xenograft, in comparison with the histopathological markers, Ki-67 and phosphorylated EGFR (phospho-EGFR). Methods: An EGFR-dependent human tumor xenograft model (A431) was established in female BALB/c athymic mice, which were divided into three groups: one control group and two treatment groups. Mice in the treatment groups were orally administered a partial regression dose (100 mg/kg/day) or the maximum tolerated dose of gefitinib (200 mg/kg/day), once daily for 2 days. Mice in the control group were administered the vehicle (0.1% Tween 80). Tumor size was measured before and 3 days after the start of treatment. Biodistribution of H-3-FLT and F-18-FDG (%ID/g/kg) was examined 3 days after the start of the treatment. Tumor cell proliferative activity with Ki-67 was determined. Immunohistochemical staining of EGFR and measurement of phospho-EGFR were also performed. Results: High expression levels of EGFR and Ki-67 were observed in the A431 tumor. After the treatment with 100 and 200 mg/kg gefitinib, the uptake levels of H-3-FLT in the tumor were significantly reduced to 67% and 61% of the control value, respectively (0.39 +/- 0.09, 0.36 +/- 0.06, 0.59 +/- 0.11% ID/g/kg for 100 mg/kg, 200 mg/kg, and control groups, respectively; p < 0.01 vs. control), but those of F-18-FDG were not. After the treatment with 100 and 200 mg/kg gefitinib, the expression levels of Ki-67 in the tumor were markedly decreased (4.6 +/- 2.4%, 6.2 +/- 1.8%,and 10.4 +/- 5.7% for 100 mg/kg, 200 mg/kg, and control groups, respectively, p < 0.01 vs. control). The expression levels of the phospho-EGFR protein also significantly decreased (29% and 21% of the control value for 100, and 200 mg/kg, respectively p < 0.01 vs. control). There was no statistically significant difference in tumor size between pre- and post-treatments in each group. Conclusion: In our animal model, H-3-FLT uptake levels significantly decreased after the treatment with two different doses of gefitinib before a significant change in tumor size was observed. These results were confirmed by the immunohistochemical staining of Ki-67 and phospho-EGFR protein immunoassay. Thus, it was indicated that early changes in H-3-FLT uptake may reflect the antiproliferative effect of gefitinib in a mouse model of a human epidermoid cancer.
  • Kenji Hirata, Kouzou Kubo
    EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 40 (7) 1119 - 1119 1619-7070 2013/07 [Refereed][Not invited]
  • Naoya Hattori, Ichiro Yabe, Kenji Hirata, Tohru Shiga, Ken Sakushima, Sachiko Tsuji-Akimoto, Hidenao Sasaki, Nagara Tamaki
    CLINICAL NUCLEAR MEDICINE 38 (5) 315 - 320 0363-9762 2013/05 [Refereed][Not invited]
     
    Purpose: Cognitive impairment is a representative neuropsychiatric presentation that accompanies Parkinson disease (PD). The purpose of this study was to localize the cerebral regions associated with cognitive impairment in patients with PD using quantitative SPECT. Patients and Methods: Thirty-two patients with PD (mean [SD] age, 75 [8] years; 25 women; Hoehn-Yahr scores from 2 to 5) underwent quantitative brain SPECT using I-123 iodoamphetamine. Parametric images of regional cerebral blood flow (rCBF) were spatially normalized to the standard brain atlas. First, voxel-by-voxel comparison between patients with PD with versus without cognitive impairment was performed to visualize overall trend of regional differences. Next, the individual quantitative rCBF values were extracted in representative cortical regions using a standard region-of-interest template to compare the quantitative rCBF values. Results: Patients with cognitive impairment showed trends of lower rCBF in the left frontal and temporal cortices as well as in the bilateral medial frontal and anterior cingulate cortices in the voxel-by-voxel analyses. Region-of-interest-based analysis demonstrated significantly lower rCBF in the bilateral anterior cingulate cortices (right, 25.8 [5.5] vs 28.9 [5.7] mL per 100 g/min, P < 0.05; left, 25.8 [5.8] vs 29.1 [5.7] mL per 100 g/min, P < 0.05) associated with cognitive impairment. Conclusions: Patients with cognitive impairment showed lower rCBF in the left frontal and temporal cortices as well as in the bilateral medial frontal and anterior cingulate cortices. The results suggested dysexecutive function as an underlining mechanism of cognitive impairment in patients with PD.
  • Osamu Manabe, Naoya Hattori, Kenji Hirata, Kazuo Itoh, Masao Hosokawa, Hiroaki Takahashi, Noriko Oyama-Manabe, Nagara Tamaki
    Journal of nuclear medicine : official publication, Society of Nuclear Medicine 54 (5) 670 - 6 0161-5505 2013/05 [Refereed][Not invited]
     
    UNLABELLED: The metabolic activity of the primary tumor is an important variable in (18)F-FDG PET interpretation for presurgical staging, because this activity is likely to affect the possibility of detection of malignant involvement in lymph nodes (LNs). The purpose of this study was to reevaluate the diagnostic accuracy of (18)F-FDG PET/CT for the presurgical staging of esophageal squamous cell carcinoma (SCC) in correlation with the (18)F-FDG avidity of the primary lesions. METHODS: One hundred fifty-six patients (mean age ± SD, 61.4 ± 8.0 y) underwent (18)F-FDG PET/CT before surgical esophagectomy and LN dissection. LN metastasis was identified using the fusion of PET and CT images with increased (18)F-FDG uptake greater than the background activity of the adjacent structures. The results of the patients' (18)F-FDG PET/CT examinations for LN involvement were compared with the histopathologic results to investigate the diagnostic accuracy of (18)F-FDG PET/CT for tumor staging. In addition, we examined the correlation between the diagnostic accuracy of (18)F-FDG PET/CT for LN involvement and the (18)F-FDG avidity of the primary lesions, to investigate the effect of tumor aggressiveness on the diagnosis of LN metastasis. RESULTS: The diagnostic accuracy of (18)F-FDG PET/CT for LN metastasis showed a low sensitivity, ranging from 29.3% to 53.3%, whereas the specificity was higher than 89.8% in regional thoracic nodes and in remote areas of the cervical and abdominal regions. The (18)F-FDG uptake of the primary lesions positively correlated with that of the metastatic LNs in the thoracic field (R = 0.52, P < 0.05). As a result, our receiver-operating-characteristic analyses demonstrated an area under the curve value of 0.73, with the optimal cutoff value at a maximum standardized uptake value of 3.3 in patients with mid to high (18)F-FDG avidity in the primary lesions (maximum standardized uptake value ≥ 5). CONCLUSION: This study showed that the avidity of the primary esophageal SCCs affected the detectability of lymph nodal metastases. If primary lesions of esophageal SCC present with a low (18)F-FDG uptake, PET/CT may have a limited role for initial staging because of low sensitivity to detect lymph node metastases.
  • Hisayasu Saito, Satoshi Kuroda, Kenji Hirata, Keiichi Magota, Tohru Shiga, Nagara Tamaki, Daisuke Yoshida, Satoshi Terae, Naoki Nakayama, Kiyohiro Houkin
    CEREBROVASCULAR DISEASES 35 (4) 370 - 377 1015-9770 2013 [Refereed][Not invited]
     
    Background: Vulnerable and inflamed plaques in the carotid artery are at high risk of ischemic stroke, suggesting the importance of diagnostic modalities to detect them in patients with carotid stenosis with high sensitivity and specificity. Although many investigators have reported that magnetic resonance imaging (MRI) is a useful tool to predict the vulnerable components of carotid plaque, its validity is not established. On the other hand, F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) may be an alternative modality to directly identify the inflamed plaque in carotid artery stenosis. Therefore, this study aimed at evaluating the validity of MRI and FDG-PET to predict vulnerable and inflamed carotid plaque. Methods: This prospective study totally included 25 patients who underwent carotid endarterectomy (CEA) for carotid artery stenosis at our institute between January 2009 and January 2012. Prior to CEA, FDG-PET, black-blood T1-weighted imaging (BB-T1WI), and 3-dimensional time-of-flight (TOF) imaging were performed. The specimens were stained with hematoxylin-eosin to assess the different plaque components (lipid, hemorrhage, calcification, and fibrous tissue). In addition, they were stained with primary antibodies against CD68 (activated macrophages) and matrix metalloproteinase (MMP)-9. Results: High FDG uptake was detected in 13 (52.0%) of 25 patients. All of them had lipid-rich plaque. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) to identify the lipid-rich plaques were all 100% for FDG-PET. More importantly, all of the FDG-positive plaques had strong immunoreactivity against both CD68 and MMP-9. There was a significant correlation between the findings on FDG-PET and those on immunohistochemistry against CD68 and MMP-9 (p = 0.006 and 0.004, respectively). On the other hand, 16 (64.0%) of 25 patients had high signal intensity plaque on BB-T1WI. In 7 of these 16 patients, the lesions also showed high signal intensity on TOF imaging. All of them had a large intraplaque hemorrhage. The sensitivity, specificity, PPV, and NPV to identify a large intraplaque hemorrhage were 70, 100, 100, and 83%, respectively, for MRI. Conclusions: These findings suggest that FDG-PET and MRI are complementary to predict high-risk carotid plaque, such as lipid-rich or hemorrhagic plaque. FDG-PET can accurately predict the lipid-rich and inflamed plaque. MRI is valuable to identify unstable plaque with a large intraplaque hemorrhage. The combination of these two modalities may play an important role in predicting carotid plaque at high risk of ischemic stroke. Copyright (C) 2013 S. Karger AG, Basel
  • Kenji Hirata, Tohru Shiga, Noriyuki Fujima, Osamu Manabe, Reiko Usui, Yuji Kuge, Nagara Tamaki
    Acta radiologica (Stockholm, Sweden : 1987) 53 (10) 1155 - 7 0284-1851 2012/12/01 [Refereed][Not invited]
     
    Encephalitis is generally diagnosed by clinical symptoms, cerebrospinal fluid examination, and imaging studies including CT, magnetic resonance imaging (MRI), and perfusion single photon emission tomography (SPECT). However, the role of positron emission tomography (PET) in diagnosis of encephalitis remains unclear. A 49-year-old woman presenting with coma and elevated inflammatory reaction was diagnosed as having encephalitis according to slow activity on electroencephalogram, broad cortical lesion in MR fluid attenuated inversion recovery image, and increased blood flow demonstrated by SPECT. PET revealed increased accumulation of (11)C-methionine (MET) in the affected brain tissues. After the symptom had improved 2 months later, the accumulation of MET as well as the abnormal findings of MR imaging and SPECT was normalized. This case indicated that MET PET may monitor the activity of encephalitis.
  • Alisa Klaipetch, Osamu Manabe, Noriko Oyama-Manabe, Satoru Chiba, Masanao Naya, Shiro Yamada, Kenji Hirata, Hiroyuki Tsutsui, Nagara Tamaki
    Clinical nuclear medicine 37 (12) 1184 - 5 0363-9762 2012/12 [Refereed][Not invited]
     
    We report the usefulness of F-FDG PET/CT for the detection and therapy evaluation of the infective vegetation. A 64-year-old man with history of aortic valve replacement presented with 2 months of fever without identifiable cause. Echocardiogram showed no inflammation vegetation or abnormality of mechanical valve function. FDG PET/CT with 50 IU/kg IV heparin revealed focal uptakes near the mechanical aortic valve. After antibiotics therapy, fever was ameliorated, and FDG PET/CT findings showed markedly decreased uptake of the lesions. FDG PET/CT is a powerful tool to detect endocarditis even in patients with no anatomical abnormalities.
  • Haruto Uchino, Satoshi Kuroda, Kenji Hirata, Tohru Shiga, Kiyohiro Houkin, Nagara Tamaki
    STROKE 43 (10) 2610 - 2616 0039-2499 2012/10 [Refereed][Not invited]
     
    Background and Purpose-Clinical features and pathophysiology of postoperative hyperperfusion in moyamoya disease are still unclear. This study was aimed to clarify the incidence and time course of postoperative hyperperfusion and to determine the independent predictors of postoperative hyperperfusion in moyamoya disease. Methods-This prospective study included 41 patients who underwent surgical revascularization for moyamoya disease. Using O-15-gas positron emission tomography, hemodynamic and metabolic parameters were quantified before surgery. Using single photon emission computed tomography, cerebral blood flow was serially measured just after surgery and on 2 and 7 days postsurgery. A multivariate logistic regression analysis was conducted to test the effect of multiple variables on postoperative hyperperfusion. Results-Postoperative hyperperfusion was observed in 29 (50.0%) of 58 operated hemispheres. The incidence of both radiological and symptomatic hyperperfusion was significantly higher in adult patients than in pediatric ones (P=0.026 and P=0.0037, respectively). Hyperperfusion just after surgery more often led to subsequent neurological deficits (P=0.033). A multivariate analysis revealed that preoperative cerebral blood volume increase was an independent predictor of both radiological and symptomatic hyperperfusion after surgery in adult moyamoya disease (OR, 6.6 and 12.3, respectively). Conclusions-Postoperative hyperperfusion after surgical revascularization is not rare in moyamoya disease. Adult patients with a cerebral blood volume increase may be at high risk for radiological and symptomatic hyperperfusion after surgery. Careful perioperative management would reduce surgical complications and improve long-term outcome in moyamoya disease. (Stroke. 2012; 43:2610-2616.)
  • Osamu Manabe, Noriko Oyama-Manabe, Klaipetch Alisa, Kenji Hirata, Kazuo Itoh, Satoshi Terae, Yoshiro Matsui, Nagara Tamaki
    Clinical nuclear medicine 37 (6) 599 - 601 0363-9762 2012/06 [Refereed][Not invited]
     
    We report 2 rare cases of primary cardiac paraganglioma demonstrated with multimodality imaging. Both a 46-year-old woman who presented with hypertension (case 1) and a 46-year-old woman without any symptoms (case 2) had mediastinal tumors depicted by CT and MRI. Both cases showed intense focal uptakes in the tumors with iodine-123-meta-iodobenzylguanidine SPECT. Case 2 also underwent 18F-FDG PET/CT and revealed a focal uptake. CT angiography detected the arterial feeder and venous drainages, information that was useful for the operation. After surgical removal, pathology confirmed primary cardiac paraganglioma in both cases. 18F-FDG PET/CT was also useful in ruling out residual or recurrent tumors.
  • Shiga Tohru, Takeuchi Wataru, Morimoto Yuichi, Kubo Naoki, Hirata Kenji, Kobashi Keiji, Hattori Naoya, Tamaki Nagara
    JOURNAL OF NUCLEAR MEDICINE 53 0161-5505 2012/05/01 [Refereed][Not invited]
  • Kenji Hirata, Shunsuke Terasaka, Tohru Shiga, Naoya Hattori, Keiichi Magota, Hiroyuki Kobayashi, Shigeru Yamaguchi, Kiyohiro Houkin, Shinya Tanaka, Yuji Kuge, Nagara Tamaki
    EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 39 (5) 760 - 770 1619-7070 2012/05 [Refereed][Not invited]
     
    Purpose Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor and its prognosis is significantly poorer than those of less malignant gliomas. Pathologically, necrosis is one of the most important characteristics that differentiate GBM from lower grade gliomas; therefore, we hypothesized that F-18 fluoromisonidazole (FMISO), a radiotracer for hypoxia imaging, accumulates in GBM but not in lower grade gliomas. We aimed to evaluate the diagnostic value of FMISO positron emission tomography (PET) for the differential diagnosis of GBM from lower grade gliomas. Methods This prospective study included 23 patients with pathologically confirmed gliomas. All of the patients underwent FMISO PET and 18F-fluorodeoxyglucose (FDG) PET within a week. FMISO images were acquired 4 h after intravenous administration of 400 MBq of FMISO. Tracer uptake in the tumor was visually assessed. Lesion to normal tissue ratios and FMISO uptake volume were calculated. Results Of the 23 glioma patients, 14 were diagnosed as having GBM (grade IV glioma in the 2007 WHO classification), and the others were diagnosed as having non-GBM (5 grade III and 4 grade II). In visual assessment, all GBM patients showed FMISO uptake in the tumor greater than that in the surrounding brain tissues, whereas all the non-GBM patients showed FMISO uptake in the tumor equal to that in the surrounding brain tissues (p <= 0.001). One GBM patient was excluded from FDG PET study because of hyperglycemia. All GBM patients and three of the nine (33%) non-GBM patients showed FDG uptake greater than or equal to that in the gray matter. The sensitivity and specificity for diagnosing GBM were 100 and 100% for FMISO, and 100 and 66% for FDG, respectively. The lesion to cerebellum ratio of FMISO uptake was higher in GBM patients (2.74 +/- 0.60, range 1.71-3.81) than in non-GBM patients (1.22 +/- 0.06, range 1.09-1.29, p <= 0.001) with no overlap between the groups. The lesion to gray matter ratio of FDG was also higher in GBM patients (1.46 +/- 0.75, range 0.91-3.79) than in non-GBM patients (1.07 +/- 0.62, range 0.66-2.95, p <= 0.05); however, overlap of the ranges did not allow clear differentiation between GBM and non-GBM. The uptake volume of FMISO was larger in GBM ( 27.18 +/- 10.46%, range 14.02- 46.67%) than in non- GBM ( 6.07 +/- 2.50%, range 2.12- 9.22%, p <= 0.001). Conclusion These preliminary data suggest that FMISO PET may distinguish GBM from lower grade gliomas.
  • Masaaki Hokari, Satoshi Kuroda, Yusuke Simoda, Haruto Uchino, Kenji Hirata, Tohru Shiga, Naoki Nakayama, Kiyohiro Houkin, Nagara Tamaki
    NEUROLOGIA MEDICO-CHIRURGICA 52 (5) 350 - 353 0470-8105 2012/05 [Refereed][Not invited]
     
    Crossed cerebellar diaschisis (CCD) often occurs after ischemic or hemorrhagic stroke that damages the cortico-ponto-cerebellar pathway. However, CCD due to cerebral hyperperfusion following cerebrovascular reconstruction is rare. A 61-year-old woman presented with transient CCD due to cerebral hyperperfusion following bypass surgery for adult moyamoya disease. She developed transient weakness of the right extremities and was diagnosed with moyamoya disease. First, she underwent superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis with indirect synangiosis on the left. Postoperative course was uneventful. Subsequently, she underwent STA-MCA anastomosis with indirect synangiosis on the right. She complained of mild headache on the right, and single photon emission computed tomography (SPECT) performed on the 7th postoperative day demonstrated hyperperfusion in the right frontal and temporal lobes associated with hypoperfusion in the left cerebellum. Magnetic resonance (MR) imaging demonstrated no new lesions and MR angiography showed patent STA-MCA bypass. Subsequent SPECT showed disappearance of both hyperperfusion and CCD. This case strongly suggests that cerebral hyperperfusion after bypass surgery for moyamoya disease may cause transient CCD. Although the clinical significance is still obscure, this phenomenon indicates the cortico-ponto-cerebellar pathway is interrupted due to hyperperfusion, suggesting the development of hyperperfusion syndrome. Careful observation of cerebral hemodynamics after bypass surgery is warranted to avoid hyperperfusion-related complications.
  • Takashi Kato, Shuji Ikari, Kenji Hirata, Takuro Machida, Hideaki Nakamura, Takashi Meguro, Takayuki Morita, Toshiyuki Takahashi, Nagara Tamaki, Shoichi Horita
    Case Reports in Gastroenterology 6 (2) 415 - 424 1662-0631 2012/05 [Refereed][Not invited]
     
    Intraductal oncocytic papillary neoplasm (IOPN) of the pancreas is a rare pancreatic tumor. To date, there have been three case reports of IOPN which showed strong positivity on 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), raising the possibility of distinguishing IOPNs from other intraductal papillary mucinous neoplasms (IPMNs) using FDG-PET. However, all three cases had large tumors, approximately 10 cm in diameter, and there are no case reports of FDG-PET findings of small IOPNs, i.e. tumors the average size of malignant IPMNs (3-5 cm). We report two cases with IOPN of average size with FDG-PET findings. Computed tomography (CT) showed a multilocular cystic lesion 4 cm in diameter with a mural nodule 1 cm in diameter (case 1) and a cystic lesion 5 cm in diameter with a papillary mural nodule 4 cm in diameter (case 2). FDG-PET showed abnormal uptake at the same location as the pancreatic tumor revealed by CT in both cases. The maximum standardized uptake values of the lesions were 3.4 and 4.2, respectively. Surgical resection was performed and the tumor was diagnosed as IOPN with carcinoma in situ (case 1) and IOPN with minimal invasion (case 2). FDG-PET may be useful for diagnosing malignancy in IOPN, as it is in IPMN. However, in our two cases, strong accumulation was not observed in the IOPNs, which were within the average size range of malignant IPMNs. Copyright © 2012 S. Karger AG, Basel.
  • Ichiro Yabe, Sachiko Tsuji-Akimoto, Tohru Shiga, Shinsuke Hamada, Kenji Hirata, Mika Otsuki, Yuji Kuge, Nagara Tamaki, Hidenao Sasaki
    JOURNAL OF THE NEUROLOGICAL SCIENCES 315 (1-2) 55 - 59 0022-510X 2012/04 [Refereed][Not invited]
     
    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by loss of motor neuron and various cognitive deficits including writing errors. C-11-flumazenil (FMZ), the positron emission tomography (PET) GABA(A) receptor ligand, is a marker of cortical dysfunction. The objective of this study was to investigate the relationship between cognitive deficits and loss of neuronal integrity in ALS patients using C-11-FMZ PET. Ten patients with ALS underwent both neuropsychological tests and C-11-FMZ-PET. The binding potential (BP) of FMZ was calculated from C-11-FMZ PET images. There were no significant correlations between the BP and most test scores except for the writing error index (WEI), which was measured by the modified Western Aphasia Battery - VB (WAB-IVB) test. The severity of writing error was associated with loss of neuronal integrity in the bilateral anterior cingulate gyrus with mild right predominance (n = 9; x = 4 mm, y = 36 mm, z = 4 mm, Z = 5.1). The results showed that writing errors in our patients with ALS were related to dysfunction in the anterior cingulate gyrus. (c) 2011 Elsevier B.V. All rights reserved.
  • Takuhito Narita, Hidefumi Aoyama, Kenji Hirata, Shunsuke Onodera, Tohru Shiga, Hiroyuki Kobayashi, Junichi Murata, Shunsuke Terasaka, Shinya Tanaka, Kiyohiro Houkin
    JAPANESE JOURNAL OF CLINICAL ONCOLOGY 42 (2) 120 - 123 0368-2811 2012/02 [Refereed][Not invited]
     
    Two glioblastoma multiforme patients underwent F-18-FMISO (fluoromisonidazole) positron emission tomography study to access the tumor oxygenation status before and immediately after fractionated radiotherapy concomitant with temozolomide chemotherapy. In both cases, a prominent F-18-FMISO tumor accumulation observed in the first study was notably decreased in the second study, which was supposed to be a reoxygenation of the tumor. As far as we investigated, this is the first report of the changes of oxygenation status in glioblastoma multiforme treated through radiation therapy with temozolomide.
  • Shimbo Daisuke, Kuroda Satoshi, Nakayama Naoki, Kazumata Ken, Hirata Kenji, Shiga Tohru, Houkin Kiyohiro, Tamaki Nagara
    CEREBROVASCULAR DISEASES 34 19  1015-9770 2012 [Refereed][Not invited]
  • Yae Harada, Kenji Hirata, Hiroyuki Kobayashi, Reiko Usui, Tohru Shiga, Satoshi Terae, Hiroki Shirato, Nagara Tamaki
    CLINICAL NUCLEAR MEDICINE 37 (1) 110 - 111 0363-9762 2012/01 [Refereed][Not invited]
     
    A 31-year-old woman presenting with tonic seizures was radiologically investigated using CT, MR imaging, and positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) and C-11 methionine (MET). Initial CT, C-11 MET PET, and F-18 FDG PET suggested a low-grade tumor such as oligodendroglial tumor. However, MR imaging findings strongly suggested venous infarction. We chose observation rather than surgical intervention. Two months later, self-regression of the lesion confirmed the diagnosis of venous infarction. Therefore, to avoid unnecessary invasive operations, we should keep in mind that high C-11 MET accumulation does not always signify a tumoral lesion but is sometimes the result of vascular pathology.
  • Hiroaki Motegi, Satoshi Kuroda, Naoki Nakayama, Kenji Hirata, Tohru Shiga, Nagara Tamaki
    NEUROLOGIA MEDICO-CHIRURGICA 51 (10) 720 - 723 0470-8105 2011/10 [Refereed][Not invited]
     
    A 47-year-old male presented with asymptomatic mild (45%) internal carotid artery (ICA) stenosis associated with familial hypercholesterolemia. Fluorine-18-fluorodeoxyglucose ([(18)F]FDG) positron emission tomography (PET) showed that the carotid plaque had high uptake of [(18)F]FDG on the initial scan. He was treated with antiplatelet agent, but subsequently developed retinal artery occlusion on the ipsilateral side. The patient safely underwent carotid endarterectomy (CEA). Histological examination revealed that the plaque was rich in lipids and activated macrophages. Previous large randomized clinical trials have clarified that CEA is an effective therapeutic option to reduce the risk for subsequent ischemic stroke in patients with severe (more than 70%) ICA stenosis. The case strongly suggests that [18F]FDG PET may be a useful modality to identify inflamed and/or vulnerable carotid plaque and may be useful to predict the risk for subsequent ischemic stroke even in patients with mild to moderate ICA stenosis (less than 70%).
  • Rinnosuke Kuramoto, Kenji Hirata, Toshiki Takei, Nobuhiko Oridate, Seigo Suzuki, Yosuke Yamada, Masahiro Imamura, Nagara Tamaki
    CLINICAL NUCLEAR MEDICINE 36 (7) 582 - 583 0363-9762 2011/07 [Refereed][Not invited]
     
    We report a case that fluorodeoxyglucose positron emission tomography (FDG PET)/computed tomography (CT) depicted systemically multiple lesions of methotrexate (MTX)-associated lymphoproliferative disorders. A 70-year-old man receiving MTX for rheumatoid arthritis complained of neck swelling. FDG PET/CT revealed multiple FDG-avid lesions in lymph nodes, lungs, bones, and muscles. Lesions in bones and muscles were not detected on X-CT. Final diagnosis of cervical node was confirmed as MTX-associated lymphoproliferative disorders. FDG PET/CT performed 148 days after discontinuing MTX demonstrated complete remission.
  • Shiga Tohru, Takeuchi Wataru, Kubo Naoki, Hirata Kenji, Hattori Naoya, Usui Reiko, Morimoto Yuichi, Kobashi Keiji, Umegaki Kikuo, Tamaki Nagara
    JOURNAL OF NUCLEAR MEDICINE 52 0161-5505 2011/05/01 [Refereed][Not invited]
  • Kenji Hirata, Yuji Kuge, Chiaki Yokota, Akina Harada, Koichi Kokame, Hiroyasu Inoue, Hidekazu Kawashima, Hiroko Hanzawa, Yuji Shono, Hideo Saji, Kazuo Minematsu, Nagara Tamaki
    NEUROSCIENCE LETTERS 495 (3) 210 - 215 0304-3940 2011/05 [Refereed][Not invited]
     
    Although an enriched environment enhances functional recovery after ischemic stroke, the mechanism underlying this effect remains unclear. We previously reported that brain derived neurotrophic factor (BDNF) gene expression decreased in rats housed in an enriched environment for 4 weeks compared to those housed in a standard cage for the same period. To further clarify the relationship between the decrease in BDNF and functional recovery, we investigated the effects of differential 2-week housing conditions on the mRNA of BDNF and protein levels of proBDNF and mature BDNF (matBDNF). After transient occlusion of the right middle cerebral artery of male Sprague-Dawley rats, we divided the rats into two groups: (1) an enriched group housed multiply in large cages equipped with toys, and (2) a standard group housed alone in small cages without toys. Behavioral tests before and after 2-week differential housing showed better neurological recovery in the enriched group than in the standard group. Synaptophysin immunostaining demonstrated that the density of synapses in the pen-infarct area was increased in the enriched group compared to the standard group, while infarct volumes were not significantly different. Real-time reverse transcription polymerase chain reaction. Western blotting and immunostaining all revealed no significant difference between the groups. The present results suggest that functional recovery cannot be ascribed to an increase in matBDNF or a decrease in proBDNF but rather to other underlying mechanisms. (C) 2011 Elsevier Ireland Ltd. All rights reserved.
  • Kuroda Satoshi, Maruichi Katsuhiko, Nakayama Naoki, Houkin Kiyohiro, Hirata Kenji, Shiga Tohru, Tamaki Nagara
    STROKE 42 (3) E183  0039-2499 2011/03 [Refereed][Not invited]
  • Masanao Naya, Koichi Morita, Keiichiro Yoshinaga, Osamu Manabe, Daisuke Goto, Kenji Hirata, Chietsugu Katoh, Nagara Tamaki, Hiroyuki Tsutsui
    European journal of nuclear medicine and molecular imaging 38 (3) 491 - 8 1619-7070 2011/03 [Refereed][Not invited]
     
    PURPOSE: Smoking cessation has been shown to normalize the coronary endothelial dysfunction in healthy young smokers. However, its effect has not been explored in middle-aged smokers with a longer history of smoking. Therefore, we compared the effects of smoking cessation on coronary vasomotor response between both young and middle-aged smokers and identified the predictor for its improvement. METHODS: This study investigated 14 young healthy smokers (age 25.2 ± 2.3 years), 13 middle-aged smokers (age 42.0 ± 6.5 years) and 10 non-smokers. Myocardial blood flow (MBF) was measured by using (15)O-water positron emission tomography (PET). RESULTS: At baseline, the ratio of MBF during the cold pressor test (CPT) to that at rest (MBF(CPT/rest)), the index of coronary endothelial function, was significantly decreased in both young and middle-aged smokers compared to non-smokers (1.24 ± 0.20 and 1.10 ± 0.39 vs 1.53 ± 0.18, p < 0.05 and p < 0.001, respectively). The ratio of MBF during adenosine triphosphate infusion to that at rest was significantly decreased in middle-aged smokers compared to young smokers and non-smokers (3.34 ± 1.52 vs 4.43 ± 0.92 and 4.69 ± 1.25, p < 0.05, respectively). MBF(CPT/rest) at 1 month after smoking cessation significantly increased in young smokers, but not in middle-aged smokers. By multivariate analysis, baseline serum malondialdehyde-modified low-density lipoprotein (MDA-LDL) was an independent predictor for the changes in MBF(CPT/rest) after smoking cessation (β = -0.45, p < 0.05). CONCLUSION: Coronary endothelial dysfunction was reversible by short-term smoking cessation in young smokers, but not in middle-aged smokers, which was associated with serum MDA-LDL levels. Long-term smoking exposure could lead to more advanced coronary endothelial dysfunction and atherosclerosis possibly via oxidative stress.
  • Yuji Shono, Chiaki Yokota, Yuji Kuge, Shinsuke Kido, Akina Harada, Koichi Kokame, Hiroyasu Inoue, Mariko Hotta, Kenji Hirata, Hideo Saji, Nagara Tamaki, Kazuo Minematsu
    BRAIN RESEARCH 1376 60 - 65 0006-8993 2011/02 [Refereed][Not invited]
     
    Recent studies have demonstrated that animals housed in an enriched environment after an experimental stroke obtained a better functional outcome than those housed in a standard cage; however, little is known about the gene expression associated with this functional recovery. The purpose of the present study was to elucidate the expression of genes in an enriched environment after experimental stroke in the ischemic and non-ischemic sides of the cortices. Transient focal brain ischemia was produced by the occlusion of the right middle cerebral artery (t-MCAO) in male Sprague Dawley rats. The rats were divided into 3 groups: ischemic rats housed in the enriched environment, ischemic rats housed in standard cages, and non-ischemic rats in standard cages. Four weeks after t-MCAO, the rats were sacrificed and gene expression was examined. Motor function was improved in ischemic rats housed in the enriched environment compared with those in standard cages; however, there were no significant differences in the size of the infarct area between the ischemic rats in the enriched environment and those in standard cages. Decreases in the expression of Egr-1, -2, and BDNF mRNA in both sides of the cortices were detected in rats housed in the enriched environment, indicating that gene expression was altered throughout the brain at 4 weeks after transient focal ischemia. (C) 2010 Elsevier B.V. All rights reserved.
  • Shigeru Yamaguchi, Hiroyuki Kobayashi, Kenji Hirata, Tohru Shiga, Shinya Tanaka, Junichi Murata, Shunsuke Terasaka
    JOURNAL OF NEURO-ONCOLOGY 101 (2) 335 - 341 0167-594X 2011/01 [Refereed][Not invited]
     
    Gliomas are regionally heterogeneous tumors. Positron emission tomography (PET) with F-18-fluorodeoxyglucose (FDG) and C-11-methionine (MET) evaluates the heterogeneity of histological malignancy within the tumor. We present two patients with oligodendrocytic tumors that showed discrepancies in the highest uptake areas with these two tracers. PET studies with MET and FDG were performed on the same day, 2 weeks before surgery. In both cases, biopsy specimens were separately obtained from the highest MET and FDG uptake areas guided by intraoperative neuronavigation. Histological examinations demonstrated that the specimens from the highest MET uptake area revealed low-grade oligoastrocytoma or oligodendroglioma, whereas histological anaplasias were contained in the specimens from the highest FDG uptake area. With gliomas with oligodendroglial components, the MET uptake ratio does not always correspond to histological anaplasia, which can be detected only by FDG PET. Sole application of MET PET for preoperative evaluation may lead to misunderstanding of histological heterogeneity in gliomas, especially those with oligodendroglial components. FDG and MET tracers play complementary roles in preoperative evaluation of gliomas.
  • Kenji Hirata, Naoya Hattori, Chietsugu Katoh, Tohru Shiga, Satoshi Kuroda, Naoki Kubo, Reiko Usui, Yuji Kuge, Nagara Tamaki
    NUCLEAR MEDICINE COMMUNICATIONS 32 (1) 63 - 70 0143-3636 2011/01 [Refereed][Not invited]
     
    Objective Cerebral blood flow (CBF) estimation with C(15)O(2) PET usually assumes a single tissue compartment model and a fixed brain-blood partition coefficient of water. However, the partition coefficient may change in pathological conditions. The purpose of this study was to investigate the changes in the partition coefficient of water in pathological regions and its effect on regional CBF assessment. Methods The study protocol included 22 patients with occlusive cerebrovascular disease to compare the partition coefficients among three regions (infarction area, noninfarct hypoperfusion area, and contralateral area) in the pathological brain (analysis A), and to compare the CBF estimated by using a fixed partition coefficient and CBF estimated using floating partition coefficients (analysis B). Results The partition coefficient in the infarction area (0.55 +/- 0.07 ml/g) was lower than that in the contralateral normal cortex (0.68 +/- 0.05 ml/g), whereas noninfarct hypoperfusion area did not show a significant change (0.67 +/- 0.06 ml/g). As a result, the use of a fixed partition coefficient of normal volunteers (0.70 ml/g) resulted in an underestimation in regional CBF by 12% in infarction area (P<0.05), whereas the estimation errors were smaller and induced no significant difference in the noninfarct hypoperfusion area or in contralateral areas. Conclusion The partition coefficient is stable except for the infarction area, and CBF estimation using a fixed partition coefficient of normal volunteers provides clinically appreciable information in patients with cerebrovascular disease. Nucl Med Commun 32:63-70 (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.
  • 黒田敏, 中山若樹, 平田健司, 志賀哲, 玉木長良, 宝金清博
    脳循環代謝 (一社)日本脳循環代謝学会 22 (1) 78 - 78 0915-9401 2010/11 [Not refereed][Not invited]
  • Shigeru Yamaguchi, Shunsuke Terasaka, Hiroyuki Kobayashi, Takuhito Narita, Kenji Hirata, Satoshi Shiga, Reiko Usui, Shinya Tanaka, Kanako Kubota, Junichi Murata, Katsuyuki Asaoka
    Neurological Surgery 38 (7) 621 - 628 0301-2603 2010/07 [Refereed][Not invited]
     
    Object: The aim of this study was to evaluate the usefulness of combined use of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) and 11C-methionine (MET) for the preoperative evaluation of gliomas and to investigate the feasibility of PET in glioma surgery. Methods: Preoperative FDG (n = 25) and/or MET (n = 22) PET studies were performed in 26 patients with primary and recurrent adult gliomas. We qualitatively (visual analysis) and quantitatively evaluated the uptake of both tracers in the tumor location. For quantitative analysis, data were analyzed by a region of interest method using the standard uptake value (SUV) and a calculated uptake ratio. We investigated the correlation among the tracer uptake ratios, histological tumor grading and tumor proliferation activity. Results: On visual inspection, no patient (0/9) with high uptake of FDG had low grade gliomas and 94% (14/15) had high grade gliomas, while uptake of MET was present in all patients. On quantitative analysis, histological tumor grade was most reflected in FDG uptake ratio compared with contralateral white matter. The tumor/normal brain (T/N) uptake ratio of MET increased stepwise with increasing histological grade but was not significantly different from tumor grade. In comparison of FDG and MET uptake ratio with proliferation activity, a significant correlation was shown for FDG uptake ratio, but not for the T/N ratio of MET. Conclusions: MET is useful in detecting and delineating the extent of the tumor, but not in evaluating tumor grade and proliferative activity. The FDG uptake ratio correlates well with tumor grade and proliferative activity. Preoperative PET studies with FDG and MET play complementary roles in the planning of glioma surgery, and integrated information from both tracers helps us to plan the extent of tumor resection.
  • Masami Sato, Masayuki Inubushi, Tohru Shiga, Kenji Hirata, Shozo Okamoto, Tomohito Kamibayashi, Kazuhide Tanimura, Nagara Tamaki
    ANNALS OF NUCLEAR MEDICINE 23 (3) 311 - 316 0914-7187 2009/05 [Refereed][Not invited]
     
    The purpose of this study was to investigate whether improvement of regional inflammatory findings in knee joints of rheumatoid arthritis (RA) could be detected by positron-emission tomography (PET) using F-18-Fluorodeoxyglucose (FDG) after acupuncture treatments, as well as improvement of systemic inflammatory markers. Six RA patients (all female, 61 +/- A 12 years old) received 10 acupuncture treatments in 2 months, to 11 traditional acupuncture points around a knee joint considered effective on RA. A visual analogue scale (VAS) for intensity of pain, knee joint range of motion (ROM), face scale for patient mood, and modified health assessment questionnaire (MHAQ) for disability of daily activities were assessed just before and after acupuncture. Maximum standardized uptake value (SUVmax) and the volume with SUV more than 1.0 [Volume(SUV > 1)] on FDG-PET images as well as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels were also measured before and after the treatments. VAS, ROM, face scale and MHAQ improved in all patients and significantly after acupuncture, but no significant change was detected in ESR, CRP, SUVmax, or Volume(SUV > 1). Acupuncture relieves symptom, remedies physical function, and improves quality of life in RA patients, but may have no or very limited anti-inflammatory effect systemically. The regional effects of acupuncture are unlikely to be induced through reduction of regional inflammation. We believe this clinical study is the first step for elucidating therapeutic mechanisms of acupuncture, which must be important for the rational use and further development of acupuncture.
  • Shigeru Yamaguchi, Shunsuke Terasaka, Hiroyuki Kobayashi, Tohru Shiga, Reiko Usui, Kenji Hirata, Kanako Kubota, Junichi Murata, Yoshinobu Iwasaki
    JOURNAL OF NEUROSURGERY-PEDIATRICS 3 (4) 270 - 275 1933-0707 2009/04 [Refereed][Not invited]
     
    Object. Intrinsic tumors arising in the dorsal midbrain cause obstructive hydrocephalus and have an indolent clinical course. Positron emission tomography (PET) with fluorine-18-labeled fluorodeoxyglucose (FDG) and L-[methyl-(11)C]methionine (MET) was used to evaluate the biological behaviors of dorsal midbrain tumors. Methods. The authors report on 4 patients (3 males and 1 female) with dorsal midbrain tumors who presented with obstructive hydrocephalus. A diagnosis was made with MR imaging in each patient. To manage the hydrocephalus, endoscopic third ventriculostomy was performed in all cases. The patients did not undergo any other surgical procedures except endoscopic biopsy procedure, chemotherapy, or radiation therapy. The patients in 3 cases underwent FDG- and MET-PET within 6 months of CSF-diverting procedures, and the patient in I case underwent PET 10 years after the procedure. Results. After the CSF-diverting procedure, clinical symptoms resolved or improved in all patients. Gliosis or glial proliferation was diagnosed in I patient, and possible low-grade glioma in 2 patients. Although all tumors appeared hyperintense on T2-weighted MR images, their appearance on T1-weighted images was variable (iso- and/or hypointense), and partial lesion enhancement was observed on images from 2 patients. On the other hand, the PET features of these lesions were almost identical, and the scans did not show a high uptake of FDG and MET compared with the cortical uptake in a normal brain. The mean tumor tissue/normal tissue ratio of FDG uptake was 0.65, and that of MET was 0.99. Conclusions. Positron emission tomography findings suggested that the indolent dorsal midbrain lesion had nontumorous characteristics, thus supporting a good prognosis. Positron emission tomography studies may be more informative and predictive of the biological behavior of dorsal midbrain tumors than a biopsy procedure. (DOI: 10.3171/2008.12.PEDS08323)
  • Kenji Hirata, Tohru Shiga, Kanako C. Kubota, Shozo Okamoto, Tomohito Kamibayashi, Nagara Tamaki
    CLINICAL NUCLEAR MEDICINE 34 (3) 180 - 181 0363-9762 2009/03 [Refereed][Not invited]
     
    A 55-year-old woman underwent radioiodine therapy for papillary carcinoma of the thyroid. Post-therapeutic I-131 scan revealed radioiodine uptake in the pelvic region and in the thyroid bed. CT revealed a huge mass connected to the uterus. The tumor was operated on and histologically proven to be a leiomyoma of the uterus. Some physiological conditions or nonthyroidal diseases can cause false positives in patients with postoperative thyroid cancer. We suggest that uterine leiomyoma might be added to the pitfall list, although the mechanism of I-131 uptake remains unclear.
  • Tohru Shiga, Yuichi Morimoto, Naoki Kubo, Norio Katoh, Chietsugu Katoh, Wataru Takeuchi, Reiko Usui, Kenji Hirata, Shinichi Kojima, Kikuo Umegaki, Hiroki Shirato, Nagara Tamaki
    JOURNAL OF NUCLEAR MEDICINE 50 (1) 148 - 155 0161-5505 2009/01 [Refereed][Not invited]
     
    An autoradiography method revealed intratumoral inhomogeneity in various solid tumors. It is becoming increasingly important to estimate intratumoral inhomogeneity. However, with low spatial resolution and high scatter noise, it is difficult to detect intratumoral inhomogeneity in clinical settings. We developed a new PET system with CdTe semiconductor detectors to provide images with high spatial resolution and low scatter noise. Both phantom images and patients' images were analyzed to evaluate intratumoral inhomogeneity. Methods: This study was performed with a cold spot phantom that had 6-mm-diameter cold sphenoid defects, a dual-cylinder phantom with an adjusted concentration of 1:2, and an "H"-shaped hot phantom. These were surrounded with water. Phantom images and (18)F-FDG PET images of patients with nasopharyngeal cancer were compared with conventional bismuth germanate PET images. Profile curves for the phantoms were measured as peak-to-valley ratios to define contrast. Intratumoral inhomogeneity and tumor edge sharpness were evaluated on the images of the patients. Results: The contrast obtained with the semiconductor PET scanner (1.53) was 28% higher than that obtained with the conventional scanner (1.20) for the 6-mm-diameter cold sphenoid phantom. The contrast obtained with the semiconductor PET scanner (1.43) was 27% higher than that obtained with the conventional scanner (1.13) for the dual-cylinder phantom. Similarly, the 2-mm cold region between 1-mm hot rods was identified only by the new PET scanner and not by the conventional scanner. The new PET scanner identified intratumoral inhomogeneity in more detail than the conventional scanner in 6 of 10 patients. The tumor edge was sharper on the images obtained with the new PET scanner than on those obtained with the conventional scanner. Conclusion: These phantom and clinical studies suggested that this new PET scanner has the potential for better identification of intratumoral inhomogeneity, probably because of its high spatial resolution and low scatter noise.
  • 鐘ケ江香久子, 岡本祥三, 平田健司, 上林倫史, 趙松吉, 真鍋治, 久下裕司, 玉木長良
    核医学 (一社)日本核医学会 45 (3) S221 - S185 0022-7854 2008 [Not refereed][Not invited]
  • Tetsuya Inoue, Keiichiro Yoshinaga, Koichi Morita, Tohru Shiga, Kakuko Kanegae, Kenji Hirata, Shozo Okamoto, Nagara Tamaki
    ANNALS OF NUCLEAR MEDICINE 21 (5) 307 - 310 0914-7187 2007/07 [Refereed][Not invited]
     
    Iodine-131 metaiodobenzylguanidine (I-131-MIBG) therapy is an effective treatment for patients with malignant paraganglioma for which surgical resection is not indicated. We performed high-dose I-131-MIBG therapy on two patients with malignant paraganglioma and multiple bone metastases. The bone metastases were diagnosed by magnetic resonance imaging (MRI). Metastatic bone lesions were evaluated by whole-body I-131-MIBG imaging and bone scintigraphy. Whole-body I-131-MIBG imaging showed extensive metastatic bone lesions, whereas conventional bone scintigraphy did not. There was a remarkable discrepancy between I-131-MIBG imaging and bone scintigraphy in the diagnosis of metastatic bone lesions of malignant paraganglioma in our two patients. High-dose I-131-MIBG imaging may detect early stages of bone metastases, compared with bone scintigraphy, in patients with malignant paraganglioma.
  • K Nakada, T Ishibashi, T Takei, K Hirata, K Shinohara, S Katoh, SJ Zhao, N Tamaki, Y Noguchi, S Noguchi
    JOURNAL OF NUCLEAR MEDICINE 46 (2) 261 - 266 0161-5505 2005/02 [Refereed][Not invited]
     
    Salivary gland dysfunction is one of the common side effects of high-dose radioiodine therapy for thyroid cancer. The purpose of this study was to determine whether an early start of sucking lemon candy decreases salivary gland injury after radioiodine therapy. Methods: The incidence of the side effects of radioiodine therapy on the salivary glands was prospectively and longitudinally investigated in 2 groups of patients with postsurgical differentiated thyroid cancer with varying regimens for sucking lemon candy. From August 1999 to October 2000, 116 consecutive patients were asked to suck 1 or 2 lemon candies every 2-3 h in the daytime of the first 5 d after radioiodine therapy (group A). Lemon candy sucking was started within 1 h after radioiodine ingestion. From November 2000 to June 2002, 139 consecutive patients (group B) were asked to suck lemon candies in a manner similar to that of group A. In the group B, lemon candies were withheld until 24 h after the ingestion of radioiodine. Patients with salivary gland disorders, diabetes, collagen tissue diseases, or a previous history of radioiodine therapy or external irradiation to the neck were excluded. Thus, 105 patients in group A and 125 patients in group B were available for analysis. There were no statistical differences in the mean age (55.2 y vs. 58.5 y), average levels of serum free thyroxine (L-3,5,3',5'-tetraiodothyronine) (0.40 ng/dL vs. 0.47 ng/dL), and the mean dose of I-131 administered (3.96 GBq vs. 3.87 GBq) between the 2 groups. The onset of salivary side effects was monitored during hospital admission and regular follow-up on the basis of interviews with patients, a visual analog scale, and salivary gland scintigraphy using Tc-99m-pertechnetate. When a patient showed a persistent (>4 mo) dry mouth associated with a nonfunctioning pattern on salivary gland scintigraphy, a diagnosis of xerostomia was established. Results: The incidences of sialoadenitis, hypogeusia or taste loss, and dry mouth with or without repeated sialadenitis in group A versus group B were 63.8% versus 36.8% (P < 0.001), 39.0% versus 25.6% (P < 0.01), and 23.8% versus 11.2% (P < 0.005), respectively. Permanent xerostomia occurred in 15 patients in group A (14.3%) and 7 patients in group B (5.6%) (P < 0.05). In both groups, bilateral involvement of the parotid gland was the most frequently seen and was followed by bilateral involvement of the submandibular gland. Conclusion: An early start of sucking lemon candy may induce a significant increase in salivary gland damage. Lemon candy should not be given until 24 h after radioiodine therapy.
  • K Furuyama, M Kondo, K Hirata, H Fujita, S Sassa
    Hepatology (Baltimore, Md.) 30 (6) 1532 - 3 0270-9139 1999/12

Books etc

  • 【医療AIの普及拡大とさらなる展開 医療からヘルスケアサービスまで発展に向けた現状と展望】医療AIのための人材育成の現状と展望 北海道大学における医療AI開発者育成プログラムの活動と展望
    唐 明輝, 平田 健司, 杉森 博行, 吉村 高明, 小笠原 克彦, 中谷 純, 工藤 與亮 
    (株)インナービジョン 2023/06 (ISBN: 9784910561301) 
    わが国においては高齢化,医療者の偏在,働き方改革など,多くの医療課題が山積みになっている。それらの課題を解決するため,医療AIの導入および展開が喫緊の課題となっている。そのような背景で,東北大学を主幹に,北海道大学と岡山大学が連携する医療AI人材育成プロジェクト「『Global×Localな医療課題解決を目指した最先端AI研究開発』人材育成教育拠点」が,文部科学省・大学教育再生戦略推進費「保健医療分野におけるAI研究開発加速に向けた人材養成産学協働プロジェクト」に採択された[2020(令和2)～2024(令和6)年度]。北海道大学では,大学院医学研究院連携研究センター医療AI教育研究分野を中心に,東北大学および岡山大学と連携し,協力校である北海道情報大学,北海道科学大学とともに,民間企業や自治体の支援を受けながら,多様性に富んだ事業推進体制による医療AI開発者養成プログラム(Clinical AI Human Resources Development Program:CLAP)を2021(令和3)年度から本格的に展開し始めた。(著者抄録)
  • 玉木, 長良, 平田, 健司, 真鍋, 治 
    文光堂 2022/01 (ISBN: 9784830637643) xii, 321p
  • 平田 健司, 藤間 憲幸, 杉森 博行, 工藤 與亮 
    (株)インナービジョン 2021/09 (ISBN: 9784910561059)
  • 真鍋 治, 小梁川 和宏, 納谷 昌直, 相川 忠夫, 平田 健司, 小林 健太郎, 古家 翔, 真鍋 徳子, 立石 宇貴秀 
    金原出版(株) 2020/08
  • 平田 健司, 藤後 廉, 小川 貴弘, 長谷山 美紀, 志賀 哲 
    (株)インナービジョン 2019/06 
    AI特集号ということで、これを読まれる方々はすでに人工知能(AI)、ディープラーニング、畳み込みニューラルネットワーク(convolutional neural network:CNN)の知識を十分身につけていると考え、早速核医学診断への利用の話を始めたい。核医学においても、AI研究はディープラーニングとディープラーニング以外とに分けて考えるとわかりやすい。ディープラーニング以外のものを先に見ておくと、例えば、骨シンチグラフィの診断を補助して良悪性を提案し、骨転移の広がりを定量するソフトウエアや、心筋血流シンチグラフィから心血管イベントのリスクを予測するソフトウエアなどが想起される。もっと古くは、脳血流画像に解剖学的標準化とノーマルデータベースとの比較を行って、血流低下部位を可視化するソフトウエアもAIと言えるであろう。核医学におけるAI利用の歴史は長いと言える。これらに対して、本稿のテーマであるディープラーニングは、むろん深層のニューラルネットワークを用いる手法のことを指す。図1に示すように、目的に応じて、画像の分類あるいは回帰、病変領域の抽出、セグメンテーション、そして投与量低減、吸収補正(どちらも画像生成タスク)などに分けられる。具体的な研究例を挙げながら解説していきたい。AIの論文を読む時のコツは、何を入力として、何を出力するAIを構築したのかを、最初に見つけることである。複雑なネットワーク構造に注目してしまうと、重要なポイントを見逃しかねない。以下、本稿でも意識的に「入力」「出力」を明示する。(著者抄録)
  • A new PET scanner with semiconductor detector reveals intratumoral inhomogeneous cell activity with high spatial and energy resolution
    Shiga T, Kubo N, Morimoto Y, Katoh N, Katoh C, Ueno Y, Hirata K, Usui R, Kobayashi K, Takeuchi W, Shirato H, Tamaki N 
    2009

Conference Activities & Talks

  • 核医学～近未来核医学の向かう道-診断・治療の精度をあげる最新手法～ 核医学におけるAIの活用と課題
    平田 健司, 杉森 博行, 藤間 憲幸, 豊永 拓哉, 工藤 與亮
    日本医学放射線学会秋季臨床大会抄録集  2022/08  (公社)日本医学放射線学会
  • Tsubasa Kunieda, Ren Togo, Noriko Nishioka, Yukie Shimizu, Shiro Watanabe, Kenji Hirata, Keisuke Maeda, Takahiro Ogawa 0001, Kohsuke Kudo, Miki Haseyama
    GCCE  2022
  • 小林 雄太, 永井 利幸, 平田 健司, 常田 慧徳, 加藤 喜哉, 小森山 弘和, 神谷 究, 小西 崇夫, 佐藤 琢真, 表 和徳, 工藤 與亮, 今野 哲, 安斉 俊久
    日本サルコイドーシス/肉芽腫性疾患学会雑誌  2021/10  日本サルコイドーシス
  • 平田 健司, 藤間 憲幸, 杉森 博行, 工藤 與亮
    INNERVISION  2021/09  (株)インナービジョン
  • IgG4関連肺病変を背景に生じた非角化型扁平上皮癌の一例
    大塚 拓也, 伊藤 祥太郎, 松本 宗人, 氏家 秀樹, 常田 慧徳, 平田 健司, 朝比奈 肇, 加賀 基知三, 松野 吉宏
    日本病理学会会誌  2021/03  (一社)日本病理学会
  • 待機時間2時間は充分か 顎骨SPECT定量解析における撮像待機時間の研究
    秦 浩信, 下村 悟史, 今待 賢治, 舩山 恭祐, 浅香 卓哉, 佐藤 淳, 平田 健司, 松坂 方士, 盛 洋一, 南部 敏和, 北川 善政
    核医学  2021  (一社)日本核医学会
  • パーキンソン病における両側STN-DBS後の体重増加と刺激位置との関連についての検討
    江口 克紀, 白井 慎一, 山崎 和義, 濱内 祝嗣, 松島 理明, 加納 崇裕, 笹森 徹, 平田 健司, 関 俊隆, 志賀 哲, 大槻 美佳, 寳金 清博, 佐々木 秀直, 矢部 一郎
    日本定位・機能神経外科学会プログラム・抄録集  2020/12  (一社)日本定位・機能神経外科学会
  • 河上 壮志, 杉森 博行, 平田 健司, 孫田 惠一, 加藤 千恵次
    核医学技術  2020/10  (NPO)日本核医学技術学会
  • 河上 壮志, 平田 健司, 杉森 博行, 加藤 千恵次
    核医学技術  2019/10  (NPO)日本核医学技術学会
  • FDG PETのテクスチャ解析を用いた心臓サルコイドーシスの予後検討  [Not invited]
    真鍋 治, 平田 健司, 真鍋 徳子, 古家 翔, 小梁川 和宏, 大平 洋, 相川 忠夫, 納谷 昌直, 辻野 一三, 玉木 長良, 志賀 哲
    核医学  2019/10  (一社)日本核医学会
  • 心臓サルコイドーシス評価のFDG-PET/CT撮像にヘパリン注射は必要か?  [Not invited]
    古家 翔, 真鍋 治, 大平 洋, 納谷 昌直, 相川 忠夫, 小梁川 和宏, 辻野 一三, 真鍋 徳子[大山], 平田 健司, 志賀 哲
    核医学  2019/10  (一社)日本核医学会
  • メルケル細胞癌におけるPET-CTのFDG集積に関する細胞学的検討
    北村 真也, 柳 輝希, 高島 有香, 今福 恵輔, 秦 洋郎, 清水 宏, 平田 健司, 上原 治朗, 石田 雄大, 大塚 篤司
    日本皮膚科学会雑誌  2019/03  (公社)日本皮膚科学会
  • Ren Togo, Takahiro Ogawa, Osamu Manabe, Kenji Hirata, Tohru Shiga, Miki Haseyama
    2019 IEEE 1st Global Conference on Life Sciences and Technologies, LifeTech 2019  2019/03 
    © 2019 IEEE. This paper presents a method for extracting important regions for deep learning models in the identification of cardiac sarcoidosis using polar map images. Although deep learning-based detection methods have widely studied, they are still often called black boxes. Since high reliability for provided results from computer-aided diagnosis systems is important toward clinical applications, this problem should be solved. In this paper, we try to visualize important regions for deep learning-based models for improvement of understanding to clinicians. We monitor the variance of confidence of a model constructed with a deep learning-based feature and define it as a contribution value toward the estimated label. We visualize important regions for models based on the contribution value.
  • 123I-FP-CITにおけるシミュレーションを用いたTexture解析のReproducibility評価
    池本 裕貴, 大崎 洋充, 平田 健司, 上原 歩夏, 清水 賢, 野上 敬太, 柏倉 健一, 立石 宇貴秀
    核医学  2018/11  (一社)日本核医学会
  • 15O-水心筋血流PETにおけるMonte Carlo scaling複合型SSS散乱補正の検討  [Not invited]
    孫田 惠一, 志賀 哲, 真鍋 治, 納谷 昌直, 相川 忠夫, 新山 大樹, 平田 健司, 加藤 千恵次, 藤田 勝久, 玉木 長良
    核医学  2018/11  (一社)日本核医学会
  • FMISO-PETによる心臓サルコイドーシス病変の評価  [Not invited]
    古家 翔, 真鍋 治, 大平 洋, 納谷 昌直, 相川 忠夫, 小梁川 和宏, 渡邊 史郎, 小林 健太郎, 平田 健司, 志賀 哲, 真鍋 徳子
    核医学  2018/11  (一社)日本核医学会
  • Strategy to develop convolutional neural network-based classifier for diagnosis of whole-body FDG PET images  [Not invited]
    Keisuke Kawauchi, Kenji Hirata, Seiya Ichikawa, Osamu Manabe, Kentaro Kobayashi, Shiro Watanabe, Miki Haseyama, Takahiro Ogawa, Ren Togo, Tohru Shiga, Chietsugu Katoh
    Society of Nuclear Medicine and Molecular Imaging Annual Meeting (SNMMI)  2018/06
  • 心サルコイドーシスにおけるFDG集積定量評価の再現性  [Not invited]
    真鍋 治, 平田 健司, 大平 洋, 納谷 昌直, 相川 忠夫, 真鍋 徳子, 志賀 哲
    核医学  2017/09  (一社)日本核医学会
  • Use of convolutional neural network as the first step of fully automated tumor detection on 11C-methionine brain PET  [Not invited]
    Hirata Kenji, Takeuchi Wataru, Yamaguchi Shigeru, Kobayashi Hiroyuki, Terasaka Shunsuke, Toyonaga Takuya, Watanabe Shiro, Kobayashi Kentaro, Manabe Osamu, Kobashi Keiji, Shiga Tohru, Tamaki Nagara
    JOURNAL OF NUCLEAR MEDICINE  2016/05
  • Steroid therapy affects the cardiac metabolic shift and requires the careful attention in evaluation of the cardiac sarcoidosis with FDG PET/CT  [Not invited]
    Manabe Osamu, Yoshinaga Keiichiro, Ohira Hiroshi, Oyama-Manabe Noriko, Tsujino Ichizo, Hirata Kenji, Kikuchi Hisaya, Nishimura Masaharu, Tamaki Nagara
    JOURNAL OF NUCLEAR MEDICINE  2016/05
  • 中咽頭癌に合併し多発骨転移との鑑別が困難であった急性リンパ性白血病の一例  [Not invited]
    渡邊 史郎, 真鍋 治, 平田 健司, 菊地 恒矢, 牧野 俊一, 豊永 拓哉, 小林 健太郎, 内山 裕子, 志賀 哲, 加納 里志, 玉木 長良
    核医学  2016/02  (一社)日本核医学会
  • Primary mucinous cell carcinoma of the skinのリンパ節転移に関するPET-CT所見の検討
    北村 真也, 秦 洋郎, 稲村 有香, 今福 恵輔, 坂下 智博, 平田 健司, 清水 宏
    日本皮膚科学会雑誌  2015/07  (公社)日本皮膚科学会
  • 小動物用PETを用いた11C‐FlumazenilのBinding potential解析におけるMaximum a posteriori再構成の評価  [Not invited]
    孫田惠一, 久保直樹, 趙松吉, 久下裕司, 平田健司, 服部直也, 志賀哲, 加藤千恵次, 玉木長良
    核医学  2011
  • 黒田敏, 中山若樹, 平田健司, 志賀哲, 玉木長良, 宝金清博
    脳循環代謝  2010  (一社)日本脳循環代謝学会
  • 長内俊也, 黒田敏, 中山若樹, 平田健司, 平賀哲, 玉木長良, 岩崎喜信
    脳循環代謝  2008
  • 丸一勝彦, 黒田敏, 中山若樹, 志賀哲, 平田健司, 玉木長良, 岩崎喜信
    脳循環代謝  2008
  • 多発性骨髄腫における全身methionine‐PETの有用性:FDG‐PETとの比較  [Not invited]
    鐘ケ江香久子, 岡本祥三, 平田健司, 上林倫史, 趙松吉, 真鍋治, 久下裕司, 玉木長良
    核医学  2008
  • 骨転移マーカー1CTPを用いた骨転移評価の役割―骨シンチグラフィ,FDG‐PETとの比較―  [Not invited]
    鐘ケ江香久子, 真鍋治, 岡本祥三, 平田健司, 吉永恵一郎, 志賀哲, 趙松吉, 玉木長良
    核医学  2007
  • 多発性骨髄腫に対するMET‐PETの有用性の検討‐FDG‐PETとの比較‐  [Not invited]
    鐘ケ江香久子, 森田浩一, 岡本祥三, 真鍋治, 平田健司, 吉永恵一郎, 井上哲也, 趙松吉, 玉木長良
    核医学  2007

Works

  • Metavol
    Kenji Hirata 2014/01 - Today

MISC

Awards & Honors

  • 2023/09 北海道大学医学部 エクセレント・ティーチャー優秀賞
  • 2022/07 Japanese College of Radiology Fellow of Japanese College of Radiology
  • 2021/11 日本核医学会 日本核医学会賞
  • 2019/08 北海道大学医学部 エクセレント・ティーチャー優秀賞
  • 2017/11 核医学画像解析研究会 菅野賞
  • 2016/05 Asian School of Nuclear Medicine Rising NM Professional Challenge, Gold Award
  • 2016/04 日本医学放射線学会 優秀論文賞
  • 2015/11 日本核医学会 リターニー奨励賞
  • 2015/04 日本医学放射線学会 CyPos賞Silver Medal
  • 2013/11 日本核医学会 研究奨励賞 最優秀賞
  • 2013/06 Society of Nuclear Medicine Poster Award, Neuroscience
  • 2012/04 日本医学放射線学会 CyPos賞Gold Medal

Research Grants & Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2023/06 -2026/03 
    Author : 安井 博宣, 稲波 修, 平田 健司, 久下 裕司
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2023/04 -2026/03 
    Author : 工藤 崇, 井手口 怜子, 西 弘大, 平田 健司
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2023/04 -2026/03 
    Author : 玉木 長良, 酒井 晃二, 平田 健司, 真鍋 治, 鈴木 弦, 全 完
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2022/04 -2026/03 
    Author : 小川 美香子, 平田 健司, 久下 裕司, 鍛代 悠一
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2022/04 -2025/03 
    Author : 秦 浩信, 北川 善政, 平田 健司, 三輪 建太, 今待 賢治, 佐藤 淳, 松坂 方士, 浅香 卓哉
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2022/04 -2025/03 
    Author : 山口 秀, 平田 健司, 茂木 洋晃
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2022/04 -2025/03 
    Author : 永井 礼子, 武田 充人, 正木 直樹, 高桑 恵美, 杉森 博行, 平田 健司, 齋木 佳克
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2022/04 -2025/03 
    Author : 北川 善政, 竹内 康人, 渡邊 史郎, 平田 健司, 大賀 則孝, 佐藤 淳, 犬伏 正幸
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2021/04 -2025/03 
    Author : 久下 裕司, 安井 博宣, 小川 美香子, 平田 健司, 水野 雄貴
     
    近年、フェロトーシスと呼ばれる新しい細胞死様式が報告され、フェロトーシスを誘導する薬剤が新たながん治療薬として注目されている。このフェロトーシスの進行には、トランスフェリン受容体1 (TfR1) が深く関与することが知られている。本研究の目的は、TfR1の特異的イメージングを可能とする新たなPETイメージング剤を合成し、PETによるTfR1イメージングがフェロトーシス誘導剤の治療効果予測/判定やフェロトーシス誘導剤の開発に有効な手段となるか否かを明らかにすることにある。 本目的達成のため、これまでに主に新たなPETイメージング剤の合成検討、及びIn vitro細胞実験を行った。その結果、TfR1への親和性を有する7残基直鎖ペプチド (DT7) を母体とした68Ga標識プローブ（68Ga-DT7）が、T98G (TfR1高発現細胞株) に対してTfR1特異的に集積することを見出した。一方で、その集積量はやや低かったことから、分子内に2つのDT7ペプチドを有する2価DT7を新たに設計し、合成に成功した。しかし、68Gaで標識した2価DT7のT98Gへの集積量は予想に反して低かった。さらに、直鎖上のDT7ペプチドを環状化した環化ペプチドを合成し、T98Gへの集積量を評価したが、TfR1特異的集積量の向上には繋がらなかった。 上記検討結果から、TfR1への親和性がより高いリガンドを母体としたプローブを開発する必要性が示唆された。そこで、cystine dense peptideの１種でありTfR1との高い結合親和性を有するTfRB1G3を母体としたプローブの開発を開始した。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2022/06 -2024/03 
    Author : 北川 善政, 平田 健司, 渡邊 史郎, 佐藤 淳, 浅香 卓哉, 竹内 康人, 犬伏 正幸, 網塚 憲生
  • 日本学術振興会：科学研究費助成事業 基盤研究(C)
    Date (from‐to) : 2021/04 -2024/03 
    Author : 加藤 扶美, 松野 吉宏, 平田 健司, 竹下 卓志
     
    乳癌はホルモン受容体やHER2の発現や細胞増殖能といったバイオマーカーにより複数のサブタイプに分類され、使用すべき薬剤などの治療戦略や予後が異なる。 造影ダイナミック撮像や拡散強調像などを含めたMRIからは腫瘍の形態や血流および機能、FDG PET-CTからは糖代謝といった画像バイオマーカーが非侵襲的に取得できる。MRIの機能画像の代表である拡散強調像のみかけの拡散係数（ADC値）や拡散尖度画像のK値は悪性度の指標の一つとされている。 我々の施設では、MRIやFDG PET-CTから得られる血流、機能、代謝などの画像バイオマーカーを用いて乳癌の治療抵抗性や転移・再発、予後などを予測するモデルを確立するため、乳癌患者のMRIやFDG PET-CTの画像データをテキスチャ解析という不均一さなどの人の目では捉えられないような画像の特徴を評価する方法を用いて解析し、乳癌の薬物療法の治療効果、乳癌の再発・転移の有無および予後などの臨床的データと比較し、治療抵抗性や転移・再発リスクに関連するMRIやFDG PET-CT画像の特徴を見いだすために、臨床データの収集および画像解析を進め、検討中である。 これまでにMRIを撮像した乳癌患者の症例リストを作成し、術前療法の有無とその効果、転移・再発の有無といった臨床データを収集中である。また、MRI画像データを収集しテキスチャ解析などの画像解析を行う準備を進めている。MRIの撮像体位とあわせて腹臥位でFDG PET-CTを撮像するためのプロトコール作成を行った。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2021/04 -2024/03 
    Author : 曽山 武士, 工藤 與亮, 平田 健司
     
    2021年度は、当初予定していたフュージョンビューワーの改良やデジタルファントムを用いた照射予想域の表示に留まらず、光量分布集計機能を持つ「高精度光免疫治療システム」の開発に着手した。また、このシステムの基礎的検討を行うために、①臨床解剖に即した構造を有し、②穿刺可能、③開口可能、④CTによる腫瘍・穿刺位置の客観的評価が可能な頭頸部ファントムを開発し、7月3日の第6回 日本穿刺ドレナージ研究会と11月26日の第36回 道東画像診断・治療ケア研究会で報告した。 光免疫療法のためのナビゲーションシステムを臨床で使用する際に、コーンビームCT撮像時にアーチファクトを発生しうる金属製のデバイスが問題であった。そこで、2021年度にCAD でデザインし3Dプリンターで印刷した非金属製開口器と非金属製ガイドニードルを開発し、11月26日の第36回 かしわ画像研究会で報告した。 また、歯肉癌を想定した光免疫療法のためのナビゲーションデバイスとして、2021年度にインプラントの際にドリルで下顎骨に穴を空ける技術を応用し、光ファイバーの穿刺を計画通りに行うことのできる穿刺ガイドプレートを開発し、11月26日の第36回 かしわ画像研究会で報告した。 この他、2021年度は柔軟な舌を有する頭頸部模型を開発し、これを用いて光免疫療法の術前画像と術中画像の非剛体画像レジストレーションの精度評価に取り組んだが、非剛体画像レジストレーションを行うとほとんど重ね合わせの誤差が発生せず、一方で原版の光免疫療法のためのナビゲーションシステムは重ね合わせが出来ないことが判明したため、これらの比較実験は行なっていない。
  • 日本学術振興会：科学研究費助成事業 基盤研究(C)
    Date (from‐to) : 2021/04 -2024/03 
    Author : 孫田 惠一, 山品 博子, 納谷 昌直, 平田 健司
     
    本研究では、デジタル半導体PETに対応する心臓サルコイドーシスおよび冠動脈プラークによる炎症病変を含むヒト心臓を再現したファントムを開発することである。 令和3年度はファントムの完成形を想定した上で数多くの予備実験を遂行した。年度初めに、研究分担者および研究協力者の方々とともにプロジェクト内容の確認を行い、そして製作工程に関する検討を行った。当該年度は、製作するファントムにおいて最も重要な核となる冠動脈部分をいかに再現するかに注力することとなった。冠動脈は直径2-4ミリと細い上に、心拍による心臓そのものによる動きに耐えうるような素材である必要がある。さらに、成形には心臓モデルデータより3Dプリンタを利用して行うため、取り回しが容易であることも素材選定には重要な要素であることがわかった。本報告で具体的な素材名は列挙しないが、様々な素材を用いて多くの予備実験を重ねることで最適な素材を見出すことができた。続いて、冠動脈が貼り付く部分となる心筋および心内腔部分の製作に関して検討を行った。心拍による動きはこの部分に何らかの工夫をすることで再現することとなるが、風船のように内部へ水圧を加えることで動きを再現する方法を採用することとした。従って、心筋部分はこの水圧に耐えうる素材であることが重要であるため、冠動脈部分と同様にいくつかの素材で予備実験を行うことで最適なものを見出すことができた。水圧のコントロールに関しては、様々な心拍数およびリズムを再現できることが重要である。研究計画時には水ポンプとそれをコントロールするためのプログラマブルなPCを組み合わせることで実現することを想定していたが、開発には時間を要することが判明したため研究の遅れが懸念されたため、同性能既製品を用いることを考えている。現在はその機種選定を行っているところである。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2020/04 -2024/03 
    Author : 安斉 俊久, 永井 利幸, 小川 貴弘, 横田 勲, 清水 厚志, 平田 健司, 小柴 生造, 櫻井 美佳
     
    HFpEF計500症例を目標に以下の組み入れ基準・除外基準で北海道大学病院を含む全国24施設からElectronic Data Captureシステムを用いて詳細な臨床情報を含めて登録し、各種解析を並行して実施した。組み入れ基準：外来もしくは入院心不全症例：①20歳以上でフラミンガム心不全診断基準を満足する心不全症状/所見があり、②左室駆出率50％以上かつBNP値100pg/mLを超えるもしくはN末端proBNP値400 pg/mLを超える、③本人からの文書同意が可能。除外基準：①敗血症、②心筋炎、③閉塞型肥大型心筋症、④拘束型心筋症、⑤重度の弁膜症、⑥心臓移植後あるいは待機、⑦1か月以内の予定心臓手術各種解析：①心不全マルチバイオマーカー解析 ②アレイ（ゲノムワイド関連）解析 ③網羅的メタボローム解析 ④人工知能解析 今年度は昨年度に引き続き、上記基準に該当する心不全症例の登録を開始してきた。令和4年3月末の時点で、目標症例数を超えるHFpEF664例の登録が得られ、バイオマーカー、アレイ、メタボローム解析も完了した。また、歩行動画の統一条件撮影に関しては昨年度特許申請に至った撮影アプリケーションを用いて現在歩行動画が回収できた192例に対し、歩行パターンの機械学習によるクラスター解析を行っており、教師なし学習で臨床医が判定した臨床フレイルスケールを高い弁別能で予測出来ることに加え、予後との関連も明らかになりつつある。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2020/04 -2023/03 
    Author : 平田 健司, 竹内 啓, 真鍋 治, 久下 裕司
     
    F-18 fluorodeoxyglucose (FDG)はブドウ糖類似体であり、体内に投与してからポジトロン断層法(PET)で撮影することにより、体内の糖代謝の多寡を画像化できる。原理的には、FDGを投与した直後から連続PET撮影した画像は血流の情報を含む。血流成分を抽出する試みは過去にも行われてきたが、PETの空間分解能の低さによるarterial input function (AIF)取得の困難さ等のため、臨床的に使用されるレベルには至っていない。腫瘍の血流にはdrug deliveryや治療効果判定に関する重要な情報が含まれていると考えられる。そこで本研究では新技術を導入することで、FDGによる腫瘍の糖代謝・血流の同時定量を目指した。今回申請者らが用いる新技術は、ハードウェアとしては高い空間分解能を持つ半導体PETであり、ソフトウェアとしては機械学習の一種であるdeep neural network (DNN)である。高い空間分解能は小さい血管からのAIF取得に役立ち、DNNはコンパートメントモデル・フリーで直接血流を予測するregressorとなりうる。腫瘍血流はO-15標識水のPETによる測定値をgold standardとする。1回のFDG PET撮影で患者負担の増加なしに糖代謝と同時に腫瘍血流が定量することを目指している。2年目である2021年度も新規の前向き臨床試験の立ち上げには到達できなかったが、PETのAI解析に向けて不足するエビデンスを固めるため、O-15標識水やFDGによる後ろ向き研究やファントム実験、画像診断レポートと画像とを組み合わせる研究等を行った。とくにO-15標識水に関しては、PET撮影した肺画像をUCLAの研究者とともに解析し、肺血流の定量値を得ることに成功し、腫瘍血流定量につながる成果が得られた。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2020/04 -2023/03 
    Author : 真鍋 徳子, 大平 洋, 平田 健司, 真鍋 治
     
    2020年から2021年度にかけて、心臓サルコイドーシスの診断基準の主徴候である心臓MRIとPETそれぞれを独立して定性および定量評価した。 PETにおいては、定性評価の診断能向上のために、従来の撮影に加えて後期相を追加することで生理的集積を抑制し、心臓サルコイドーシス病変の検出能と特異度向上が期待されることを報告した（後述論文リスト）。心臓MRIにおいては、従来の評価法である遅延造影の左室全体および左室のセグメント毎の定性および定量評価に加えて、既存のシネMRIデータを用いたfeature tracking法によるセグメント毎の局所的な壁運動の定量化（ストレイン解析）を追加した。遅延造影を用いたテクスチャ解析評価については、すでに先行研究で行った遅延造影CTデータを用いて方法論を確立し報告した（後述論文リスト）。 また、上記画像によるイメージングバイオマーカーに加えて、サルコイドーシス/肉芽腫性疾患学会の診断基準、及びサルコイドーシスの重症度分類結果も追記する心臓関連イベントを含む臨床経過を加えたデータベースを作成した。これらの経過はファーストオーサー1編、コレスポンディングオーサー4編として査読のある国際英文誌に掲載済みである。 また下記学会等での講演においても研究成果を報告している。 虚血および非虚血性心筋症に対する心臓MRIの現在（第61回日本核医学会学術総会 IAEA心臓核医学ワークショップ2021年11月3日WEB）、心臓機能画像のアップデート（第61回日本核医学学術総会 2021年11月5日名古屋）、心臓核医学の最新の話題（Womens Cardiologist Conference 2022年2月10日 WEB）、MRIのマッピング技術による循環器画像診断の新たな潮流．（第1回関東心臓MRI研究会2022年2月26日東京）。
  • 日本学術振興会：科学研究費助成事業 基盤研究(C)
    Date (from‐to) : 2020/04 -2023/03 
    Author : 平田 雄一, 平田 健司, 南須原 康行, 白土 博樹
     
    本研究は、将来的に重要性が増すと予想される人工知能技術を利用した医用画像診断支援システムの倫理リスクを具体化するための新しいリスクマネジメント手法の構築を試み、人工知能技術を利用した医用画像診断支援システムの倫理リスクの低減策の検討を詳細に深く行えるようにすることを目的とした。 具体的には、本研究では、医学物理学の放射線治療分野や放射線安全管理分野において、既に活用されている複雑なシステムを、システムの要素(コンポーネント)間の入力と出力により決定される制御関係の安全性に着目して解析する安全解析手法であるSTAMP(System Theoretic Accident Model and Processes)を、人工知能技術を利用した医用画像診断支援システムの倫理リスクのリスクマネジメントに応用した。 2020年度は、新しい倫理リスク・マネジメント・モデルを、医用画像に関する倫理リスク事項のネットワークを高速に処理するために本研究で購入した高速データ処理が可能な高性能ワークステーション上に実装されたSTAMPのモデリングツールであるSTAMP Workbenchを基盤とした新しい倫理リスク・モデリング・システムにより構築した。 その結果、本研究で構築した、STAMP Workbenchを基盤とした、人工知能技術を利用した医用画像診断支援システムの新しい倫理リスクマネジメント手法は、放射線治療における事故防止のための強力なツールとなりえることが明らかになった。 そして、日本放射線腫瘍学会第33回学術大会において、本研究の分担者全員と共同して上記研究結果を発表した。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2019/04 -2022/03 
    Author : Naya Masanao
     
    After the approval of the voluntary clinical trial at Hokkaido University Hospital, a total of 49 patients, including 6 healthy subjects, 9 patients with stable angina, and 34 patients with acute myocardial infarction, were studied. 18F-FDG digital PET / CT was performed, and inflammatory activity was qunatitatively measured from the SUV value. The imaging protocol was optimized to visualize arterial inflammation of the left main trunk of the coronary artery, the left anterior descending branch, the left circumflex branch, and the right coronary artery. The accumulation intensity and range of FDG accumulated in the carotid artery, thoracic aorta, and abdominal aorta could be objectively and quantitatively assessed. When the SUVmax value in the proximal part of the left anterior descending branch was compared in the three groups of healthy subjects, patients with stable angina, and patients with acute myocardial infarction, it was higher in patients with acute myocardial infarction.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    Date (from‐to) : 2016/04 -2018/03 
    Author : Hirata Kenji
     
    In this study, we first aimed to evaluate clinical usefulness of 123I-IIMU, a SPECT tracer we developed for visualizing thymidine phosphorylase expression, in patients with head-and-neck cancer. However, we were not able to administer IIMU to patients during the research period because the composition of 123I-NaI solution (purchased from the manufacturer to use for synthesis of IIMU) was changed by the manufacturer, and thus the synthesis yield was significantly reduced. Therefore, during this period, we optimized the protocol of IIMU radiosynthesis and purification conditions according to the new solution composition. We finally confirmed that IIMU was produced at a yield of 50% or more. We also administered IIMU to mice to confirm that thymidine phosphorylase was imaged. In parallel, we investigate FDG PET clinical images of thyroid cancer retrospectively and demonstrated clinical usefulness of metabolic tumor volume and heterogeneity indices (i.e., texture features).
  • 日本学術振興会：科学研究費助成事業 若手研究(B)
    Date (from‐to) : 2012 -2012 
    Author : 平田 健司
     
    原発性脳腫瘍の臨床において、手術を行わずに非侵襲的な方法で腫瘍の性質を明らかにする画像診断の果たす役割は大きい。本研究では、MRI等の既存の診断法に加えて、低酸素イメージング製剤F-18 fluoromisonidazole(FMISO)を用いたポジトロン断層撮影法(PET)を用いることで、神経膠腫の非侵襲的な鑑別診断法の確立を目指すことを目的とした。神経膠腫23症例に対して、FMISOPETを行い、その画像所見を術後病理所見と比較した。23例中14例が病理学的にWHO grade IVの神経膠芽腫であったが、これらはすべてFMISO集積亢進を示した。また残りの9例はgrade IIまたはIIIの神経膠腫であったが、これらはすべてFMISO集積陰性であった。この結果からFMISO PETによってgrade IVか、grade III以下かを鑑別することができると考えられた。さらに、神経膠芽腫のうち10例に、高分解能半導体PETでのFMISO PETおよび糖代謝を反映するFDG PETを行った。半導体PETの高い空間分解能を利用して腫瘍内の局所的な集積強弱を評価することによって、腫瘍内の分布のFMISOとFDGの分布がよく一致する症例(N=4)と、乖離する症例(N=6)が存在することを見出した。前者は嫌気性糖代謝が中心で、後者は好気性糖代謝が中心と考えられ、神経膠芽腫の中にも好気性のものと嫌気性のものが存在することがわかった。両者の治療反応性や予後の差異について今後研究を進める予定である。また、本研究に関連して、脳腫瘍の診断に用いられるメチオニンPETが、非腫瘍性の脳炎の診断にも有用であることを見出したので、これを報告した。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2006 -2008 
    Author : INUBUSHI Masayuki, TAMAKI Nagara, MORITA Koichi, SHIGA Tohru, KANEGAE Kakuko, INOUE Tetsuya, OKAMOTO Shouzo, HIRATA Kenji, YOSHINAGA Keiichiro, HATAKEYAMA Masanori
     
    近年、虚血性心疾患に対して、血管新生因子を発現する遺伝子を投与することによって血管を再生させる血管新生遺伝子治療の研究が活発に行われている。しかしこれまでは治療遺伝子の発現部位や量を生体内で確認することができず、治療効果を正確に評価することが困難であった。本研究では、治療遺伝子の発現を生体内で画像として捉える方法を確立し、さらに幹細胞/前駆細胞の細胞移植治療における移植細胞の追跡への応用を試みた。

Educational Activities

Teaching Experience

  • Machine LearningMachine Learning Hokkaido University
  • Research in Diagnostic ImagingResearch in Diagnostic Imaging Hokkaido University
  • Master's Thesis Research in Medical Sciences
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 医学院
    キーワード : 画像診断、CT、MRI、PET、SPECT、血管造影、超音波、IVR、RI内用療法
  • Basic Principles of Medicine
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 医学院
    キーワード : 画像診断、CT、MRI、PET、SPECT、血管造影、超音波、IVR、RI内用療法
  • Inter-Graduate School Classes(Educational Program):Medical AI developer training program (intensive course)
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 医学、医療、AI、機械学習、情報科学、ディープ・ラーニング、数学、統計、臨床研究
  • Inter-Graduate School Classes(Educational Program):Medical AI developer training program (intensive course)
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 医学、医療、AI、ビッグデータ、倫理、IRB、法律、産学連携、臨床研究、プロトコル
  • Inter-Graduate School Classes(Educational Program):Medical AI developer training program (intensive course)
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 医学、医療、AI、ディープ・ニューラル・ネットワーク、倫理、法律、特許、薬事承認
  • Inter-Graduate School Classes(Educational Program):Medical AI developer training program (intensive course)
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 画像診断、AI、CT、MRI、PET、超音波、インターベンショナルラジオロジー、DICOM、プログラミング、定量、遠隔画像診断
  • Inter-Graduate School Classes(Educational Program):Medical AI developer training program (intensive course)
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : AI、ゲノム、次世代シークエンサー、遺伝子パネル検査、プリシジョン・メディシン
  • Inter-Graduate School Classes(Educational Program):Medical AI developer training program (intensive course)
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 診断、治療、AI、認知症、動画解析、医薬品開発
  • Inter-Graduate School Classes(Educational Program):Medical AI developer training program (intensive course)
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : AI、手術、AI支援手術、動画解析
  • Inter-Graduate School Classes(Educational Program):Medical AI developer training program (intensive course)
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : AI、機械学習、ディープ・ラーニング、画像分類、異常検知、画像セグメンテーション、画像生成、画質改善、自然言語処理、プログラミング
  • Inter-Graduate School Classes(Educational Program):Medical AI developer training program (intensive course)
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : AI、データ・ハンドリング、DICOM、プログラミング、ディープ・ニューラル・ネットワーク、教師データ、機械学習、性能評価
  • Basic Principles of Medicine
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 医学院
    キーワード : 医学、医療、AI、ディープ・ニューラル・ネットワーク、倫理、法律、特許、薬事承認
  • Basic Principles of Medicine
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 医学院
    キーワード : 医学、医療、AI、機械学習、情報科学、ディープ・ラーニング、数学、統計、臨床研究
  • Basic Principles of Medicine
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 医学院
    キーワード : 医学、医療、AI、ビッグデータ、倫理、IRB、法律、産学連携、臨床研究、プロトコル
  • Basic Principles of Medicine
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 医学院
    キーワード : AI、ゲノム、次世代シークエンサー、遺伝子パネル検査、プリシジョン・メディシン
  • Basic Principles of Medicine
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 医学院
    キーワード : AI、データ・ハンドリング、DICOM、プログラミング、ディープ・ニューラル・ネットワーク、教師データ、機械学習、性能評価
  • Basic Principles of Medicine
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 医学院
    キーワード : AI、手術、AI支援手術、動画解析
  • Basic Principles of Medicine
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 医学院
    キーワード : AI、機械学習、ディープ・ラーニング、画像分類、異常検知、画像セグメンテーション、画像生成、画質改善、自然言語処理、プログラミング
  • Basic Principles of Medicine
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 医学院
    キーワード : 画像診断、AI、CT、MRI、PET、超音波、インターベンショナルラジオロジー、DICOM、プログラミング、定量、遠隔画像診断
  • Basic Principles of Medicine
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 医学院
    キーワード : 診断、治療、AI、認知症、動画解析、医薬品開発
  • Principles of Medicine
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 医学院
    キーワード : 画像診断、CT、MRI、PET、SPECT、血管造影、超音波、IVR、RI内用療法
  • Dissertation Research in Medical Sciences
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 医学院
    キーワード : 画像診断、CT、MRI、PET、SPECT、血管造影、超音波、IVR、RI内用療法
  • Dissertation Research in Clinical Medicine
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 医学院
    キーワード : 画像診断、CT、MRI、PET、SPECT、血管造影、超音波、IVR、RI内用療法
  • Principles of Medicine
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 医学院
    キーワード : 医学、医療、AI、ディープ・ニューラル・ネットワーク、倫理、法律、特許、薬事承認
  • Principles of Medicine
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 医学院
    キーワード : 医学、医療、AI、機械学習、情報科学、ディープ・ラーニング、数学、統計、臨床研究
  • Principles of Medicine
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 医学院
    キーワード : 医学、医療、AI、ビッグデータ、倫理、IRB、法律、産学連携、臨床研究、プロトコル
  • Principles of Medicine
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 医学院
    キーワード : AI、ゲノム、次世代シークエンサー、遺伝子パネル検査、プリシジョン・メディシン
  • Principles of Medicine
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 医学院
    キーワード : AI、データ・ハンドリング、DICOM、プログラミング、ディープ・ニューラル・ネットワーク、教師データ、機械学習、性能評価
  • Principles of Medicine
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 医学院
    キーワード : AI、手術、AI支援手術、動画解析
  • Principles of Medicine
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 医学院
    キーワード : AI、機械学習、ディープ・ラーニング、画像分類、異常検知、画像セグメンテーション、画像生成、画質改善、自然言語処理、プログラミング
  • Nuclear Medicine
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 医学部
    キーワード : 画像診断　PET　SPECT　IVR　画像定量化　アイソトープ治療

Committee Membership

  • 2023/10 - Today   European Journal of Nuclear Medicine and Molecular Imaging   Editorial Board
  • 2023/04 - Today   Japanese Association for Medical Artificial Intelligence   Councilor
  • 2015/09 - Today   BMC Cancer   Associate Editor

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