我妻 慧 (ワガツマ ケイ)

保健科学研究院 保健科学部門 医用生体理工学分野准教授
Last Updated :2025/07/16

■研究者基本情報

学位

  • 博士(保健学), 九州大学, 2018年03月
  • 修士(医科学), 横浜市立大学, 2014年03月

Researchmap個人ページ

研究者番号

  • 40738283

研究キーワード

  • SPECT
  • 神経変性疾患
  • 分子イメージング
  • 核医学
  • PET
  • Neuloimaging
  • 放射線管理学
  • 放射線技術学

研究分野

  • ライフサイエンス, 放射線科学

■経歴

経歴

  • 2025年04月 - 現在
    北里大学, 医療衛生学部, 非常勤講師, 日本国
  • 2025年04月 - 現在
    北海道大学, 大学院保健科学研究院, 准教授, 日本国
  • 2023年09月 - 現在
    聖マリアンナ医科大学, 放射線診断・IVR学講座, 研究員, 日本国
  • 2021年 - 現在
    東京都健康長寿医療センター研究所, 神経画像研究チーム, 非常勤研究員
  • 2018年 - 現在
    駒澤大学医療健康科学研究所, 客員研究員
  • 2021年05月 - 2025年03月
    北里大学, 医療衛生学部, 講師, 日本国
  • 2014年03月 - 2021年04月
    東京都健康長寿医療センター研究所, 神経画像研究チーム, 研究員
  • 2020年 - 2020年
    東洋公衆衛生学院, 非常勤講師
  • 2018年 - 2020年
    東京都立大学, 客員准教授
  • 2015年 - 2019年
    駒澤大学, 医療健康科学部 診療放射線技術科学科, 特別講師
  • 2008年04月 - 2014年02月
    公益財団法人がん研究会有明病院, 画像診断センター, 診療放射線技師, 日本国

学歴

  • 2015年04月 - 2018年03月, 九州大学, 大学院医学系学府, 保健学専攻, 日本国
  • 2012年04月 - 2014年03月, 横浜市立大学, 大学院医学研究科, 日本国
  • 2004年04月 - 2008年03月, 駒澤大学, 医療健康科学部, 診療放射線技術科学科, 日本国

委員歴

  • 2016年 - 現在
    日本核医学技術学会, 評議員, 学協会
  • 2016年 - 現在
    日本核医学技術学会関東地方会, 学術委員, 学協会
  • 2014年 - 現在
    日本放射線技術学会, 標準・企画委員会ワーキンググループ委員, 学協会
  • 2021年 - 2024年
    神奈川PET・SPECT研究会, 世話人, 学協会
  • 2019年 - 2024年
    日本放射線技術学会東京支部, 核医学技術研究班, 学協会
  • 2019年 - 2024年
    日本放射線技術学会, 代議員, 学協会
  • 2018年 - 2024年
    日本放射線技術学会東京支部, 国際化推進委員, 学協会
  • 2017年 - 2024年
    東京核医学技術研究会, 世話人, 学協会
  • 2021年11月 - 2022年05月
    第76回東京支部春期学術大会, 実行委員長, 学協会
  • 2015年 - 2018年
    日本放射線技術学会, 編集委員, 学協会
  • 2015年 - 2016年
    日本核医学技術学会, PET委員, 学協会

■研究活動情報

受賞

  • 2025年04月, 第81回日本放射線技術学会総会学術大会, 学生賞 優秀賞               
  • 2024年04月, 第80回日本放射線技術学会総会学術大会, CyPos賞 銅賞               
  • 2024年04月, 第80回日本放射線技術学会総会学術大会, 学生賞 優秀賞               
  • 2023年12月, 日本放射線技術学会東京支部・関東支部, 東京・関東支部合同研究発表大会2023優秀演題賞               
    我妻慧
  • 2023年09月, 日本核医学技術学会, 国際研究奨励賞               
    我妻慧
  • 2023年05月, 日本放射線技術学会東京支部, 第76回東京支部春期学術大会 学術奨励賞               
  • 2023年05月, 日本放射線技術学会東京支部, 第76回東京支部春期学術大会 新人研究奨励賞               
  • 2022年05月, 日本放射線技術学会, 第78回日本放射線技術学会総会学術大会 学生賞 優秀賞               
  • 2022年05月, 日本放射線技術学会東京支部, 第75回東京支部学術大会 新人研究奨励賞               
  • 2022年04月, 日本放射線技術学会東京支部, 東京支部 Reserch Award               
  • 2020年11月, 日本核医学会, 第17回日本核医学会研究奨励賞               
    我妻慧
  • 2020年05月, 日本放射線技術学会第76回総会学術大会, Bronze Award               
  • 2020年05月, 日本放射線技術学会第76回総会学術大会, Gold Award               
  • 2019年06月, 米国核医学会(SNMMI)2019, Technologist Travel Grant Award 2019               
  • 2019年04月, 日本放射線技術学会第75回総会学術大会, Bronze Award               
  • 2018年10月, 日本放射線技術学会第46回秋季学術大会, 銀賞               
  • 2018年08月, 国際医療福祉大学学会第8回学術大会, 優秀演題賞               
  • 2018年06月, 米国核医学会(SNMMI)2018, Technologist Travel Grant Award 2018               
    我妻慧
  • 2018年04月, 日本放射線技術学会第74回総会学術大会, Bronze Award               
    我妻慧
  • 2018年04月, 第12回世界核医学会(WFNMB 2018), Best Poster Award               
    我妻慧
  • 2017年11月, 日本核医学会, 2017年久田賞 銀賞               
  • 2017年11月, 日本放射線技術学会, 平成29年度 研究奨励賞・技術賞奨励賞(核医学分野)               
    我妻慧
  • 2017年10月, 日本放射線技術学会第45回秋季学術大会, 優秀演題賞               
  • 2017年04月, 日本放射線技術学会第73回総会学術大会, Gold Award               
    我妻慧
  • 2015年04月, 日本放射線技術学会第71回総会学術大会, Bronze Award               
  • 2014年11月, 日本放射線技術学会, 平成26年度 研究奨励賞・技術新人賞(核医学分野)               
    我妻慧

論文

  • Effects of a deep learning-based image quality enhancement method on a digital-BGO PET/CT system for 18F-FDG whole-body examination
    Kenta Miwa, Shin Yamagishi, Shun Kamitaki, Kouichi Anraku, Shun Sato, Tensho Yamao, Noriaki Miyaji, Kaito Wachi, Naochika Akiya, Kei Wagatsuma, Kazuhiro Oguchi
    EJNMMI Physics, 12, 1, Springer Science and Business Media LLC, 2025年03月28日, [査読有り]
    英語, 研究論文(学術雑誌), Abstract

    Background

    The digital-BGO PET/CT system, Omni Legend 32, incorporates modified block sequential regularized expectation maximization (BSREM) image reconstruction and a deep learning-based time-of-flight (TOF)-like image quality enhancement process called Precision DL (PDL). The present study aimed to define the fundamental characteristics of PDL using phantom and clinical images.

    Methods

    A NEMA IEC body phantom was scanned using the Omni Legend 32 PET/CT system. All PET/CT images were acquired over 60 and 90 s per bed position, with a 384 × 384 matrix. Phantom images were reconstructed using OSEM + PSF and BSREM at β values of 100–1,000, combined with low (LPDL), medium (MPDL), and high (HPDL) PDL. We evaluated contrast recovery, background variability, and the contrast-to-noise ratio (CNR) of a 10 mm hot sphere. Thirty clinical whole-body 18F-FDG PET/CT examinations were included. Clinical images were reconstructed using OSEM + PSF and BSREM at β values of 200, 300, 400, 500, and 600, determined based on findings from the phantom study, combined with the three PDL models. Noise levels, mean SUV (SUVmean), and the signal-to-noise ratio (SNR) of the liver as well as signal-to-background ratios (SBR) and maximum SUV (SUVmax) of lesions were evaluated. Two blinded readers evaluated visual image quality and rated several aspects to complement the analysis.

    Results

    Contrast recovery and background variability decreased as the β value increased. This trend was consistent even when PDL processing was added to BSREM. Increased strength of the PDL models led to higher CNR. Noise levels decreased as a function of increasing β values in BSREM, resulting in a higher SNR, but lower SBR. Combining PDL with BSREM resulted in all β values producing better results in terms of noise, SBR, and SNR than OSEM + PSF. As the PDL increased (LPDL < MPDL < HPDL), noise levels, SBR, and SNR became higher. The β values of 400, 200, 300, and 300 for BSREM, LPDL, MPDL, and HPDL, respectively, resulted in noise equivalent to OSEM + PSF but significantly increased the SUVmax (9%, 15%, 18%, and 27%), SBR (16%, 17%, 20%, and 32%), and SNR (17%, 19%, 31%, and 36%), respectively. The visual evaluation of image quality yielded similar scores across BSREM + PDL reconstructions, although BSREM with β = 600 combined with MPDL delivered the best overall image quality and total mean score.

    Conclusion

    The combination of BSREM and PDL significantly enhanced the SUVmax of lesions and image quality compared with OSEM + PSF. A combination of BSREM at β values of 500–600 and MPDL is recommended for oncological whole-body PET/CT imaging when using PDL on the Omni Legend.
  • 放射性医薬品投与後の患者による超音波検査者の被ばくに関する検討
    塚田 亮太, 我妻 慧, 鈴木 宏明
    日本放射線技術学会雑誌, 80, 9, 937, 942, Japanese Society of Radiological Technology, 2024年09月, [査読有り]
    日本語, 研究論文(学術雑誌)
  • Phantom test procedures for a new neuro-oncological amino acid PET tracer: [18F]fluciclovine
    Kaede Tsuzura, Kei Wagatsuma, Yuto Kamitaka, Kenta Miwa, Noriaki Miyaji, Takashi Kamiya, Noriyo Yokotsuka, Kenji Ishii
    Annals of Nuclear Medicine, Springer Science and Business Media LLC, 2024年08月29日, [査読有り], [責任著者]
    英語, 研究論文(学術雑誌)
  • Optimization of penalization function in Bayesian penalized likelihood reconstruction algorithm for [18F]flutemetamol amyloid PET images
    Shohei Fukuda, Kei Wagatsuma, Kenta Miwa, Yu Yakushiji, Yuto Kamitaka, Tensho Yamao, Noriaki Miyaji, Kenji Ishii
    Physical and Engineering Sciences in Medicine, Springer Science and Business Media LLC, 2024年08月12日, [査読有り], [責任著者]
    英語, 研究論文(学術雑誌), 31628848
  • Development of a novel phantom for tau PET imaging
    Kei Wagatsuma, Kenta Miwa, Tensho Yamao, Yuto Kamitaka, Go Akamatsu, Kanta Nakajima, Noriaki Miyaji, Kenji Ishibashi, Kenji Ishii
    Physica Medica, 123, 103399, 103399, Elsevier BV, 2024年07月, [査読有り], [筆頭著者, 責任著者]
    英語, 研究論文(学術雑誌), 31628848
  • Phantom and clinical evaluation of the Bayesian penalised likelihood reconstruction algorithm Q.Clear without PSF correction in amyloid PET images
    Kei Wagatsuma, Muneyuki Sakata, Kenta Miwa, Yumi Hamano, Hirofumi Kawakami, Yuto Kamitaka, Tensho Yamao, Noriaki Miyaji, Kenji Ishibashi, Tetsuro Tago, Jun Toyohara, Kenji Ishii
    EJNMMI Physics, 11, 1, 37, Springer Science and Business Media LLC, 2024年04月22日, [査読有り], [筆頭著者, 責任著者]
    英語, 研究論文(学術雑誌), Abstract

    Purpose

    Bayesian penalised likelihood (BPL) reconstruction, which incorporates point-spread-function (PSF) correction, provides higher signal-to-noise ratios and more accurate quantitation than conventional ordered subset expectation maximization (OSEM) reconstruction. However, applying PSF correction to brain PET imaging is controversial due to Gibbs artefacts that manifest as unpredicted cortical uptake enhancement. The present study aimed to validate whether BPL without PSF would be useful for amyloid PET imaging.

    Methods

    Images were acquired from Hoffman 3D brain and cylindrical phantoms for phantom study and 71 patients administered with [18F]flutemetamol in clinical study using a Discovery MI. All images were reconstructed using OSEM, BPL with PSF correction, and BPL without PSF correction. Count profile, %contrast, recovery coefficients (RCs), and image noise were calculated from the images acquired from the phantoms. Amyloid β deposition in patients was visually assessed by two physicians and quantified based on the standardised uptake value ratio (SUVR).

    Results

    The overestimated radioactivity in profile curves was eliminated using BPL without PSF correction. The %contrast and image noise decreased with increasing β values in phantom images. Image quality and RCs were better using BPL with, than without PSF correction or OSEM. An optimal β value of 600 was determined for BPL without PSF correction. Visual evaluation almost agreed perfectly (κ = 0.91–0.97), without depending on reconstruction methods. Composite SUVRs did not significantly differ between reconstruction methods.

    Conclusion

    Gibbs artefacts disappeared from phantom images using the BPL without PSF correction. Visual and quantitative evaluation of [18F]flutemetamol imaging was independent of the reconstruction method. The BPL without PSF correction could be the standard reconstruction method for amyloid PET imaging, despite being qualitatively inferior to BPL with PSF correction for [18F]flutemetamol amyloid PET imaging.
  • Deep Learning-Driven Estimation of Centiloid Scales from Amyloid PET Images with 11C-PiB and 18F-Labeled Tracers in Alzheimer’s Disease
    Tensho Yamao, Kenta Miwa, Yuta Kaneko, Noriyuki Takahashi, Noriaki Miyaji, Koki Hasegawa, Kei Wagatsuma, Yuto Kamitaka, Hiroshi Ito, Hiroshi Matsuda
    Brain Sciences, 14, 4, 406, 406, MDPI AG, 2024年04月21日, [査読有り]
    英語, 研究論文(学術雑誌), Background: Standard methods for deriving Centiloid scales from amyloid PET images are time-consuming and require considerable expert knowledge. We aimed to develop a deep learning method of automating Centiloid scale calculations from amyloid PET images with 11C-Pittsburgh Compound-B (PiB) tracer and assess its applicability to 18F-labeled tracers without retraining. Methods: We trained models on 231 11C-PiB amyloid PET images using a 50-layer 3D ResNet architecture. The models predicted the Centiloid scale, and accuracy was assessed using mean absolute error (MAE), linear regression analysis, and Bland–Altman plots. Results: The MAEs for Alzheimer’s disease (AD) and young controls (YC) were 8.54 and 2.61, respectively, using 11C-PiB, and 8.66 and 3.56, respectively, using 18F-NAV4694. The MAEs for AD and YC were higher with 18F-florbetaben (39.8 and 7.13, respectively) and 18F-florbetapir (40.5 and 12.4, respectively), and the error rate was moderate for 18F-flutemetamol (21.3 and 4.03, respectively). Linear regression yielded a slope of 1.00, intercept of 1.26, and R2 of 0.956, with a mean bias of −1.31 in the Centiloid scale prediction. Conclusions: We propose a deep learning means of directly predicting the Centiloid scale from amyloid PET images in a native space. Transferring the model trained on 11C-PiB directly to 18F-NAV4694 without retraining was feasible.
  • Impact of [11C]methionine PET with Bayesian penalized likelihood reconstruction on glioma grades based on new WHO 2021 classification
    Kei Wagatsuma, Kensuke Ikemoto, Motoki Inaji, Yuto Kamitaka, Shoko Hara, Kaoru Tamura, Kenta Miwa, Kaede Tsuzura, Taisei Tsuruki, Noriaki Miyaji, Kenji Ishibashi, Kenji Ishii
    Annals of Nuclear Medicine, 38, 5, 400, 407, Springer Science and Business Media LLC, 2024年03月11日, [査読有り], [筆頭著者, 責任著者]
    英語, 研究論文(学術雑誌)
  • Impact of irregular waveforms on data-driven respiratory gated PET/CT images processed using MotionFree algorithm
    Noriaki Miyaji, Kenta Miwa, Kosuke Yamashita, Kazuki Motegi, Kei Wagatsuma, Yuto Kamitaka, Tensho Yamao, Mitsutomi Ishiyama, Takashi Terauchi
    Annals of Nuclear Medicine, 37, 12, 665, 674, Springer Science and Business Media LLC, 2023年10月05日, [査読有り]
    英語, 研究論文(学術雑誌)
  • Toward standardization of tau PET imaging corresponding to various tau PET tracers: a multicenter phantom study
    Kei Wagatsuma, Kenta Miwa, Go Akamatsu, Tensho Yamao, Yuto Kamitaka, Minoru Sakurai, Naotoshi Fujita, Kohei Hanaoka, Hiroshi Matsuda, Kenji Ishii
    Annals of Nuclear Medicine, 37, 9, 494, 503, Springer Science and Business Media LLC, 2023年05月27日, [査読有り], [筆頭著者, 責任著者]
    英語, 研究論文(学術雑誌)
  • Impact of γ factor in the penalty function of Bayesian penalized likelihood reconstruction (Q.Clear) to achieve high-resolution PET images
    Kenta Miwa, Tokiya Yoshii, Kei Wagatsuma, Shogo Nezu, Yuto Kamitaka, Tensho Yamao, Rinya Kobayashi, Shohei Fukuda, Yu Yakushiji, Noriaki Miyaji, Kenji Ishii
    EJNMMI Physics, 10, 1, Springer Science and Business Media LLC, 2023年01月22日, [査読有り]
    英語, 研究論文(学術雑誌), Abstract

    Background

    The Bayesian penalized likelihood PET reconstruction (BPL) algorithm, Q.Clear (GE Healthcare), has recently been clinically applied to clinical image reconstruction. The BPL includes a relative difference penalty (RDP) as a penalty function. The β value that controls the behavior of RDP determines the global strength of noise suppression, whereas the γ factor in RDP controls the degree of edge preservation. The present study aimed to assess the effects of various γ factors in RDP on the ability to detect sub-centimeter lesions.

    Methods

    All PET data were acquired for 10 min using a Discovery MI PET/CT system (GE Healthcare). We used a NEMA IEC body phantom containing spheres with inner diameters of 10, 13, 17, 22, 28 and 37 mm and 4.0, 5.0, 6.2, 7.9, 10 and 13 mm. The target-to-background ratio of the phantom was 4:1, and the background activity concentration was 5.3 kBq/mL. We also evaluated cold spheres containing only non-radioactive water with the same background activity concentration. All images were reconstructed using BPL + time of flight (TOF). The ranges of β values and γ factors in BPL were 50–600 and 2–20, respectively. We reconstructed PET images using the Duetto toolbox for MATLAB software. We calculated the % hot contrast recovery coefficient (CRChot) of each hot sphere, the cold CRC (CRCcold) of each cold sphere, the background variability (BV) and residual lung error (LE). We measured the full width at half maximum (FWHM) of the micro hollow hot spheres ≤ 13 mm to assess spatial resolution on the reconstructed PET images.

    Results

    The CRChot and CRCcold for different β values and γ factors depended on the size of the small spheres. The CRChot, CRCcold and BV increased along with the γ factor. A 6.2-mm hot sphere was obvious in BPL as lower β values and higher γ factors, whereas γ factors ≥ 10 resulted in images with increased background noise. The FWHM became smaller when the γ factor increased.

    Conclusion

    High and low γ factors, respectively, preserved the edges of reconstructed PET images and promoted image smoothing. The BPL with a γ factor above the default value in Q.Clear (γ factor = 2) generated high-resolution PET images, although image noise slightly diverged. Optimizing the β value and the γ factor in BPL enabled the detection of lesions ≤ 6.2 mm.
  • Dedicated phantom tools using traceable 68Ge/68Ga point-like sources for dedicated-breast PET and positron emission mammography scanners
    Mio Okamoto, Tomoyuki Hasegawa, Keiichi Oda, Hiroki Miyatake, Kei Kikuchi, Yusuke Inoue, Yoko Satoh, Yuichi Inaoka, Masami Kawamoto, Koji Shima, Kenji Kanbayashi, Miho Yoshii, Tomoyuki Kanno, Kei Wagatsuma, Masatoshi Hashimoto
    Radiological Physics and Technology, 16, 1, 49, 56, Springer Science and Business Media LLC, 2023年01月09日, [査読有り]
    英語, 研究論文(学術雑誌)
  • Determination of a reliable assessment for occupational eye lens dose in nuclear medicine
    Noriaki Miyaji, Kenta Miwa, Takashi Iimori, Kei Wagatsuma, Hiroyuki Tsushima, Noriyo Yokotsuka, Taisuke Murata, Tetsuharu Kasahara, Takashi Terauchi
    Journal of Applied Clinical Medical Physics, 23, 8, e13713, Wiley, 2022年07月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), The most recent statement published by the International Commission on Radiological Protection describes a reduction in the maximum allowable occupational eye lens dose from 150 to 20 mSv/year (averaged over 5-year periods). Exposing the eye lens to radiation is a concern for nuclear medicine staff who handle radionuclide tracers with various levels of photon energy. This study aimed to define the optimal dosimeter and means of measuring the amount of exposure to which the eye lens is exposed during a routine nuclear medicine practice. A RANDO human phantom attached to Glass Badge and Luminess Badge for body or neck, DOSIRIS and VISION for eyes, and nanoDot for body, neck, and eyes was exposed to 99m Tc, 123 I, and 18 F radionuclides. Sealed syringe sources of each radionuclide were positioned 30 cm from the abdomen of the phantom. Estimated exposure based on measurement conditions (i.e., air kerma rate constants, conversion coefficient, distance, activity, and exposure time) was compared measured dose equivalent of each dosimeter. Differences in body, neck, and eye lens dosimeters were statistically analyzed. The 10-mm dose equivalent significantly differed between the Glass Badge and Luminess Badge for the neck, but these were almost equivalent at the body. The 0.07-mm dose equivalent for the nanoDot dosimeters was greatly overestimated compared to the estimated exposure of 99m Tc and 123 I radionuclides. Measured dose equivalents of exposure significantly differed between the body and eye lens dosimeters with respect to 18 F. Although accurately measuring radiation exposure to the eye lenses of nuclear medicine staff is conventionally monitored using dosimeters worn on the chest or abdomen, eye lens dosimeters that provide a 3-mm dose equivalent near the eye would be a more reliable means of assessing radiation doses in the mixed radiation environment of nuclear medicine.
  • Decreased imaging time of amyloid PET using [18F]florbetapir can maintain quantitative accuracy
    Kei Wagatsuma, Kenji Ishibashi, Masashi Kameyama, Muneyuki Sakata, Kenta Miwa, Yuto Kamitaka, Kenji Ishii
    Radiological Physics and Technology, 15, 2, 116, 124, Springer Science and Business Media LLC, 2022年06月, [査読有り], [筆頭著者, 責任著者], [国内誌]
    英語, 研究論文(学術雑誌), Shortening the amount of time required to acquire amyloid positron emission tomography (PET) brain images while maintaining the accuracy of quantitative evaluation would help to overcome motion artifacts associated with Alzheimer's disease patients. The present study aimed to validate the quantitative accuracy of [18F]florbetapir ([18F]FBP) imaging over a shorter acquisition duration. Forty participants were injected with [18F]FBP, and PET images were acquired for 50-55, 50-60, and 50-70 min after injection. Three physicians visually assessed the reprocessed [18F]FBP images using a binary scale to classify them as amyloid β (Aβ) negative or positive. A mean composite standard uptake value ratio (cSUVR) > 1.075 was defined as Aβ-positive based on receiver operating characteristic curves. Inter-reader and inter-acquisition duration agreements with visual assessment were evaluated using Cohen's kappa (κ). Binary visual discrimination of 102 for the 120 [18F]FBP images, was consistent among the three readers. Sixteen, sixteen, and fourteen of the 40 [18F]FBP images acquired for 50-55, 50-60, and 50-70 min after injection, respectively, were deemed Aβ-positive by visual assessment. The inter-rater agreement was high, and the inter-acquisition duration agreement was almost perfect. The cSUVR did not change significantly among the acquisition durations, and the acquisition duration did not affect the outcome of discrimination based on the cSUVR cutoff. A shorter acquisition duration changed the visual assessment outcomes. Stable quantitative values were derived from [18F]FBP images acquired within 5 min. cSUVR helped to improve the performance and confidence in the outcomes of visual assessment.
  • Determination of optimal regularization factor in Bayesian penalized likelihood reconstruction of brain PET images using [ 18 F]FDG and [ 11 C]PiB
    Kei Wagatsuma, Kenta Miwa, Yuto Kamitaka, Emiya Koike, Tensho Yamao, Tokiya Yoshii, Rinya Kobayashi, Shogo Nezu, Yuta Sugamata, Noriaki Miyaji, Etsuko Imabayashi, Kenji Ishibashi, Jun Toyohara, Kenji Ishii
    Medical Physics, 49, 5, 2995, 3005, Wiley, 2022年05月, [査読有り], [筆頭著者, 責任著者], [国際誌]
    英語, 研究論文(学術雑誌), PURPOSE: The Bayesian penalized likelihood (BPL) reconstruction algorithm, Q.Clear, can achieve a higher signal-to-noise ratio on images and more accurate quantitation than ordered subset-expectation maximization (OSEM). The reconstruction parameter (β) in BPL requires optimization according to the radiopharmaceutical tracer. The present study aimed to define the optimal β value in BPL required to diagnose Alzheimer disease from brain positron emission tomography (PET) images acquired using 18 F-fluoro-2-deoxy-D-glucose ([18 F]FDG) and 11 C-labeled Pittsburg compound B ([11 C]PiB). METHODS: Images generated from Hoffman 3D brain and cylindrical phantoms were acquired using a Discovery PET/computed tomography (CT) 710 and reconstructed using OSEM + time-of-flight (TOF) under clinical conditions and BPL + TOF (β = 20-1000). Contrast was calculated from images generated by the Hoffman 3D brain phantom, and noise and uniformity were calculated from those generated by the cylindrical phantom. Five cognitively healthy controls and five patients with Alzheimer disease were assessed using [18 F]FDG and [11 C]PiB PET to validate the findings from the phantom study. The β values were restricted by the findings of the phantom study, then one certified nuclear medicine physician and two certified nuclear medicine technologists visually determined optimal β values by scoring the quality parameters of image contrast, image noise, cerebellar stability, and overall image quality of PET images from 1 (poor) to 5 (excellent). RESULTS: The contrast in BPL satisfied the Japanese Society of Nuclear Medicine (JSNM) criterion of ≥55% and exceeded that of OSEM at ranges of β = 20-450 and 20-600 for [18 F]FDG and [11 C]PiB, respectively. The image noise in BPL satisfied the JSNM criterion of ≤15% and was below that in OSEM when β = 150-1000 and 400-1000 for [18 F]FDG and [11 C]PiB, respectively. The phantom study restricted the ranges of β values to 100-300 and 300-500 for [18 F]FDG and [11 C]PiB, respectively. The BPL scores for gray-white matter contrast and image noise, exceeded those of OSEM in [18 F]FDG and [11 C]PiB images regardless of β values. Visual evaluation confirmed that the optimal β values were 200 and 450 for [18 F]FDG and [11 C]PiB, respectively. CONCLUSIONS: The BPL achieved better image contrast and less image noise than OSEM, while maintaining quantitative standardized uptake value ratios (SUVR) due to full convergence, more rigorous noise control, and edge preservation. The optimal β values for [18 F]FDG and [11 C]PiB brain PET were apparently 200 and 450, respectively. The present study provides useful information about how to determine optimal β values in BPL for brain PET imaging.
  • Possibility of Enlargement in Left Medial Temporal Areas Against Cerebral Amyloid Deposition Observed During Preclinical Stage
    Etsuko Imabayashi, Kenji Ishii, Jun Toyohara, Kei Wagatsuma, Muneyuki Sakata, Tetsuro Tago, Kenji Ishibashi, Narumi Kojima, Noriyuki Kohda, Aya M. Tokumaru, Hunkyung Kim
    Frontiers in Aging Neuroscience, 14, Frontiers Media SA, 2022年04月, [査読有り]
    研究論文(学術雑誌), Neurodegenerative changes in the preclinical stage of Alzheimer’s disease (AD) have recently been the focus of attention because they may present a range of treatment opportunities. A total of 134 elderly volunteers who lived in a local community were investigated and grouped into preclinical and mild cognitive impairment stages according to the Clinical Dementia Rating test; we also estimated amyloid deposition in the brain using positron emission tomography (PET). A significant interaction between clinical stage and amyloid PET positivity on cerebral atrophy was observed in the bilateral parietal lobe, parahippocampal gyri, hippocampus, fusiform gyrus, and right superior and middle temporal gyri, as previously reported. Early AD-specific voxel of interest (VOI) analysis was also applied and averaged Z-scores in the right, left, bilateral, and right minus left medial temporal early AD specific area were computed. We defined these averaged Z-scores in the right, left, bilateral, and right minus left early AD specific VOI in medial temporal area as R-MedT-Atrophy-score, L-MedT-Atrophy-score, Bil-MedT-Atrophy-score, and R_L-MedT-Atrophy-score, respectively. It revealed that the R_L-MedT-Atrophy-scores were significantly larger in the amyloid-positive than in the amyloid-negative cognitively normal (CN) elderly group, that is, the right medial temporal areas were smaller than left in amyloid positive CN group and these left-right differences were significantly larger in amyloid positive than amyloid negative CN elderly group. The L-MedT-Atrophy-score was slightly larger (p = 0.073), that is, the left medial temporal area was smaller in the amyloid-negative CN group than in the amyloid-positive CN group. Conclusively, the left medial temporal area could be larger in CN participants with amyloid deposition than in those without amyloid deposition. The area under the receiver operating characteristic curve for differentiating amyloid positivity among CN participants using the R_L-MedT-Atrophy-scores was 0.73; the sensitivity and specificity were 0.828 and 0.606, respectively. Although not significant, a negative correlation was observed between the composite cerebral standardized uptake value ratio in amyloid PET images and L-MedT-Atrophy-score in CN group. The left medial temporal volume might become enlarged because of compensatory effects against AD pathology occurring at the beginning of the amyloid deposition.
  • Adenosine A 2A Receptor Occupancy by Caffeine After Coffee Intake in Parkinson's Disease
    Kenji Ishibashi, Yoshiharu Miura, Kei Wagatsuma, Jun Toyohara, Kiichi Ishiwata, Kenji Ishii
    Movement Disorders, 37, 4, 853, 857, Wiley, 2022年04月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), BACKGROUND: Coffee intake can decrease the risk for Parkinson's disease (PD). Its beneficial effects are allegedly mediated by caffeine through adenosine A2A receptor (A2A R) antagonist action. OBJECTIVE: We aimed to calculate occupancy rates of striatal A2A Rs by caffeine after coffee intake in PD. METHODS: Five patients with PD underwent 11 C-preladenant positron emission tomography scanning at baseline and after intake of coffee containing 129.5 mg (n = 3) or 259 mg (n = 2) of caffeine. Concurrently, serum caffeine levels were measured. RESULTS: The mean serum caffeine level (μg/mL) was 0.374 at baseline and increased to 4.48 and 8.92 by 129.5 and 259 mg of caffeine, respectively. The mean occupancy rates of striatal A2A Rs by 129.5 and 259 mg of caffeine were 54.2% and 65.1%, respectively. CONCLUSIONS: A sufficient A2A R occupancy can be obtained by drinking a cup of coffee, which is equivalent to approximately 100 mg of caffeine. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
  • Test–retest reproducibility of cerebral adenosine A2A receptor quantification using [11C]preladenant
    Jun Toyohara, Muneyuki Sakata, Kei Wagatsuma, Tetsuro Tago, Kenji Ishibashi, Kenji Ishii, Philip Elsinga, Kiichi Ishiwata
    Annals of Nuclear Medicine, 36, 1, 15, 23, Springer Science and Business Media LLC, 2022年01月, [査読有り], [国内誌]
    英語, 研究論文(学術雑誌), OBJECTIVE: To evaluate the reproducibility of cerebral adenosine A2A receptor (A2AR) quantification using [11C]preladenant ([11C]PLN) and PET in a test-retest study. METHODS: Eight healthy male volunteers were enrolled. Dynamic 90 min PET scans were performed twice at the same time of the day to avoid the effect of diurnal variation. Subjects refrained from caffeine from 12 h prior to scanning, and serum caffeine was measured before radioligand injection. Arterial blood was sampled repeatedly during scanning and the fraction of the parent compound in plasma was determined. Total distribution volume (VT) was estimated using 1- and 2-tissue compartment models (1-TCM and 2-TCM, respectively) and Logan graphical analysis (Logan plot) (t* = 30 min). Plasma-free fraction (fP) of [11C]PLN was measured and used for correction of VT values. Distribution volume ratio (DVR) was calculated from VT of target and reference regions and obtained by noninvasive Logan graphical reference tissue model (LGAR) (t* = 30 min). Absolute test-retest variability (aTRV), and intra-class correlation coefficient (ICC) of VT and DVR were calculated as indexes of repeatability. Correlation between DVR and serum concentration of caffeine (a nonselective A2AR blocker) was analyzed by Pearson's correlation analysis. RESULTS: Regional time-activity curves were well described by 2-TCM models. Estimation of VT by 2-TCM produced some erroneous values; therefore, the more robust Logan plot was selected as the appropriate model. Global mean aTRV was 20% for VT and 14% for VT/fP (ICC, 0.72 for VT and 0.87 for VT/fP). Global mean aTRV of DVR was 13% for Logan plot and 10% for LGAR (ICC, 0.70 for Logan plot and 0.81 for LGAR). DVR estimates using LGAR and Logan plot were in good agreement (r2 = 0.96). Coefficients of variation for VT, VT/fP, DVR (Logan plot), and DVR (LGAR) were 47%, 47%, 27%, and 18%, respectively. Despite low serum caffeine levels, significant concentration-dependent effects on [11C]PLN binding to target regions were observed (p < 0.01). CONCLUSIONS: In this study, moderate test-retest reproducibility and large inter-subject differences were observed with [11C]PLN PET, possibly attributable to competition by baseline amount of caffeine. Analysis of plasma caffeine concentration is recommended during [11C]PLN PET studies. TRIAL REGISTRATION: UMIN000030040.
  • First clinical assessment of [18F]MC225, a novel fluorine-18 labelled PET tracer for measuring functional P-glycoprotein at the blood–brain barrier
    Jun Toyohara, Muneyuki Sakata, Kenji Ishibashi, Pascalle Mossel, Masamichi Imai, Kei Wagatsuma, Tetsuro Tago, Etsuko Imabayashi, Nicola A. Colabufo, Gert Luurtsema, Kenji Ishii
    Annals of Nuclear Medicine, 35, 11, 1240, 1252, Springer Science and Business Media LLC, 2021年11月, [査読有り], [国内誌]
    英語, 研究論文(学術雑誌), OBJECTIVE: 5-(1-(2-[18F]fluoroethoxy))-[3-(6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl)-propyl]-5,6,7,8-tetrahydronaphthalen ([18F]MC225) is a selective substrate for P-glycoprotein (P-gp), possessing suitable properties for measuring overexpression of P-gp in the brain. This is the first-in-human study to examine safety, radiation dosimetry and P-gp function at the blood-brain barrier (BBB) of [18F]MC225 in healthy subjects. METHODS: [18F]MC225 biodistribution and dosimetry were determined in 3 healthy male subjects, using serial 2 h and intermittent 4 and 6 h whole-body PET scans acquired after [18F]MC225 injection. Dynamic [18F]MC225 brain PET (90 min) was obtained in 5 healthy male subjects. Arterial blood was sampled at various time intervals during scanning and the fraction of unchanged [18F]MC225 in plasma was determined. T1-weighted MRI was performed for anatomical coregistration. Total distribution volume (VT) was estimated using 1- and 2-tissue-compartment models (1-TCM and 2-TCM, respectively). VT was also estimated using the Logan graphical method (Logan plot) (t* = 20 min). Surrogate parameters without blood sampling (area-under the curve [AUC] of regional time-activity curves [TACs] and negative slope of calculated TACs) were compared with the VT values. RESULTS: No serious adverse events occurred throughout the study period. Although biodistribution implied hepatobiliary excretion, secretion of radioactivity from liver to small intestine through the gallbladder was very slow. Total renal excreted radioactivity recovered during 6 h after injection was < 2%ID. Absorbed dose was the highest in the pancreas (mean ± SD, 203 ± 45 μGy/MBq) followed by the liver (83 ± 11 μGy/MBq). Mean effective dose with and without urination was 17 ± 1 μSv/MBq. [18F]MC225 readily entered the brain, distributing homogeneously in grey matter regions. 2-TCM provided lower Akaike information criterion scores than did 1-TCM. VT estimated by Logan plot was well correlated with that of 2-TCM (r2 > 0.9). AUCs of TACs were positively correlated with VT (2-TCM) values (r2: AUC0-60 min = 0.61, AUC0-30 min = 0.62, AUC30-60 min = 0.59, p < 0.0001). Negative slope of SUV TACs was negatively correlated with VT (2-TCM) values (r2 = 0.53, p < 0.0001). CONCLUSIONS: This initial evaluation indicated that [18F]MC225 is a suitable and safe PET tracer for measuring P-gp function at the BBB.
  • 医療放射線に係るリスクコミュニケーションの実態調査
    大塚駿, 新井知大, 我妻慧, 菅原康晴, 堀川大輔, 篠ヶ瀬知, 吉川宏起
    日本放射線技術学会雑誌, 77, 7, 691, 699, 2021年07月, [査読有り]
    日本語, 研究論文(学術雑誌)
  • Brain 11 C-ITMM PET to longitudinally assess type 1 metabotropic glutamate receptor availability in Alzheimer's disease
    Kenji Ishibashi, Yoshiharu Miura, Kei Wagatsuma, Masashi Kameyama, Kenji Ishii
    Journal of Neuroimaging, 31, 5, 864, 868, Wiley, 2021年06月18日, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), BACKGROUND AND PURPOSE: Little evidence exists on the role of type 1 metabotropic glutamate receptor (mGluR1) in the pathophysiology of Alzheimer's disease (AD), although mGluR1 may be involved in the regulation of neuronal excitability and synaptic plasticity. We have recently reported that mGluR1 availability in the early stage of AD is equivalent to that in healthy subjects. This study aimed to address whether mGluR1 availability changes with the progression of AD. METHODS: Eight patients with AD (79.1 ± 4.6 years) underwent a total of two positron emission tomography (PET) examinations using the mGluR1 radioligand during the early-to-middle stages of AD. The mean interval was 2.8 years. Volumes-of-interest were placed on the frontal, parietal, and temporal cortices, hippocampus, anterior and posterior lobes, and vermis in the cerebellum. The binding potential (BPND ) was calculated to estimate mGluR1 availability, applying partial volume correction to the BPND values. RESULTS: No significant difference was observed in BPND values between the first and second PET examinations in the frontal cortex (p = 0.94), parietal cortex (p = 0.67), temporal cortex (p = 0.20), hippocampus (p = 0.17), anterior lobe (p = 0.73), posterior lobe (p = 0.21), and vermis (p = 0.22). CONCLUSION: This study suggests that mGluR1 availability is unchanged in the follow-up period of a few years during the early-to-middle stages of AD.
  • Centiloid scale analysis for 18F-THK5351 PET imaging in Alzheimer’s disease
    Tensho Yamao, Kenta Miwa, Kei Wagatsuma, Yoko Shigemoto, Noriko Sato, Go Akamatsu, Hiroshi Ito, Hiroshi Matsuda
    Physica Medica, 82, 249, 254, Elsevier BV, 2021年02月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), PURPOSE: A standardized method for quantification is required for analyzing PET data, but such standards have not been established for tau PET imaging. The Centiloid scale has recently been proposed as a standard method for quantifying amyloid deposition on PET imaging. Therefore, the present study aimed to apply the Centiloid scale to 18F-THK5351 PET imaging in Alzheimer's disease (AD). METHODS: We acquired 18F-THK5351 PET, 11C-PiB PET, and MR images from 47 cognitively normal (CN) individuals and 28 patients with AD with mild to moderate dementia. PET images were spatially normalized to Montreal Neurological Institute space. The PET signals were then normalized using the signal in the reference volume of interest (VOI). Target VOI for specific 18F-THK5351 retention in AD was extracted by voxel-wise comparison of PET images between the 47 CN individuals and 16 AD patients with moderate dementia. Scale anchor points were defined by the CN individuals as 0-anchor points and by that of the average of the typical AD patients as 100-anchor points. RESULTS: Specific retention of 18F-THK5351 was predominant in the angular gyrus, inferior temporal cortex, and parieto-occipital regions in patients with AD. Standardized uptake value ratio (SUVR) of 1.227 and 1.797 were defined as 0- and 100-anchor points, respectively. 18F-THK5351 PET data could be expressed using the Centiloid scale, with the SUVR of the 18F-THK5351 PET images converted to Centiloid using our VOI, the standard Centiloid reference VOI, and the following equation: Centiloid = 169.0 × SUVR-204.6. CONCLUSION: Centiloid methods can be applied to tau PET imaging using 18F-THK5351.
  • 18F-florbetapirアミロイドPETイメージングの定量解析ソフトウェアの交差検証
    我妻 慧, 三輪 建太, 坂田 宗之, 石橋 賢士, 石井 賢二
    日本放射線技術学会雑誌, 77, 1, 32, 40, (公社)日本放射線技術学会, 2021年01月, [査読有り], [筆頭著者, 責任著者]
    日本語
  • Direct comparison of brain [18F]FDG images acquired by SiPM-based and PMT-based PET/CT: phantom and clinical studies.
    Kei Wagatsuma, Muneyuki Sakata, Kenji Ishibashi, Akira Hirayama, Hirofumi Kawakami, Kenta Miwa, Yukihisa Suzuki, Kenji Ishii
    EJNMMI physics, 7, 1, 70, 70, 2020年11月23日, [査読有り], [筆頭著者, 責任著者], [国際誌]
    英語, 研究論文(学術雑誌), BACKGROUND: Silicon photomultiplier-positron emission tomography (SiPM-PET) has better sensitivity, spatial resolution, and timing resolution than photomultiplier tube (PMT)-PET. The present study aimed to clarify the advantages of SiPM-PET in 18F-fluoro-2-deoxy-D-glucose ([18F]FDG) brain imaging in a head-to-head comparison with PMT-PET in phantom and clinical studies. METHODS: Contrast was calculated from images acquired from a Hoffman 3D brain phantom, and image noise and uniformity were calculated from images acquired from a pool phantom using SiPM- and PMT-PET. Sequential PMT-PET and SiPM-PET [18F]FDG images were acquired over a period of 10 min from 22 controls and 10 patients. All images were separately normalized to a standard [18F]FDG PET template, then the mean standardized uptake values (SUVmean) and Z-score were calculated using MIMneuro and CortexID Suite, respectively. RESULTS: Image contrast, image noise, and uniformity in SiPM-PET changed 19.2, 3.5, and - 40.0% from PMT-PET, respectively. These physical indices of both PET scanners satisfied the criteria for acceptable image quality published by the Japanese Society of Nuclear Medicine of contrast > 55%, CV ≤ 15%, and SD ≤ 0.0249, respectively. Contrast was 70.0% for SiPM-PET without TOF and 59.5% for PMT-PET without TOF. The TOF improved contrast by 3.5% in SiPM-PET. The SUVmean using SiPM-PET was significantly higher than PMT-PET and did not correlate with a time delay. Z-scores were also significantly higher in images acquired from SiPM-PET (except for the bilateral posterior cingulate) than PMT-PET because the peak signal that was extracted by the calculation of Z-score in CortexID Suite was increased. The hypometabolic area in statistical maps was reduced and localized using SiPM-PET. The trend was independent of whether the images were derived from controls or patients. CONCLUSIONS: The improved spatial resolution and sensitivity of SiPM-PET contributed to better image contrast and uniformity in brain [18F]FDG images. The SiPM-PET offers better quality and more accurate quantitation of brain PET images. The SUVmean and Z-scores were higher in SiPM-PET than PMT-PET due to improved PVE. [18F]FDG images acquired using SiPM-PET will help to improve diagnostic outcomes based on statistical image analysis because SiPM-PET would localize the distribution of glucose metabolism on Z-score maps.
  • Adenosine A2A Receptor Occupancy by Long-Term Istradefylline Administration in Parkinson's Disease.
    Kenji Ishibashi, Yoshiharu Miura, Kei Wagatsuma, Jun Toyohara, Kiichi Ishiwata, Kenji Ishii
    Movement disorders : official journal of the Movement Disorder Society, 36, 1, 268, 269, 2020年11月16日, [査読有り], [国際誌]
    英語
  • Neural substrate of a cognitive intervention program using Go game: a positron emission tomography study.
    Ai Iizuka, Kenji Ishii, Kei Wagatsuma, Kenji Ishibashi, Airin Onishi, Mika Tanaka, Hiroyuki Suzuki, Shuichi Awata, Yoshinori Fujiwara
    Aging clinical and experimental research, 32, 11, 2349, 2355, 2020年11月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), BACKGROUND: Influence of cognitive intervention programs on brain activity has not been enough explored. AIMS: The aims of the present study were to clarify changes in brain activity from a cognitive intervention program utilizing the board game "Go" and to examine the relationship between brain activity and the acquisition of Go skills. METHODS: Eighteen community-dwelling older adults were randomly assigned either to an intervention group (IG), in which members attended 12 Go lessons either in groups or individually using tablet computers, or a control group (CG), in which members attended health education lectures unrelated to Go. Fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography (PET), cognitive assessments, and Go tests were performed before and after the intervention. RESULTS: The results showed different patterns of regional FDG uptake in both groups: regional cerebral glucose metabolism was significantly increased in the left middle temporal gyrus (MTG) and bilateral putamen (p < 0.01; cluster level) in the IG, and in the left superior frontal gyrus in the CG, (p < 0.01; cluster level). Furthermore, Go test scores were significantly improved in the IG (p < 0.05), and a significant association was observed between changes in Go test scores and glucose metabolism in the left MTG (p < 0.05). CONCLUSIONS AND DISCUSSION: This study indicates that a cognitive intervention program using Go may enhance brain activity. Further studies with larger populations and longer observation periods are needed to clarify the neural mechanisms underlying our Go intervention program.
  • Voxel-based morphometry focusing on medial temporal lobe structures has a limited capability to detect amyloid β, an Alzheimer's disease pathology.
    Masashi Kameyama, Kenji Ishibashi, Jun Toyohara, Kei Wagatsuma, Yumi Umeda-Kameyama, Keigo Shimoji, Kazutomi Kanemaru, Shigeo Murayama, Sumito Ogawa, Aya M Tokumaru, Kenji Ishii
    Aging, 12, 19, 19701, 19710, 2020年10月05日, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), Voxel-based morphometry (VBM) analysis of nuclear Magnetic Resonance Imaging (MRI) data allows the identification of medial temporal lobe (MTL) atrophy and is widely used to assist the diagnosis of Alzheimer's disease (AD). However, its reliability in the clinical environment has not yet been confirmed. To determine the credibility of VBM, amyloid positron emission tomography (PET) and VBM studies were compared retrospectively. Patients who underwent Pittsburgh Compound B (PiB) PET were retrospectively recruited. Ninety-seven patients were found to be amyloid negative and 116 were amyloid positive. MTL atrophy in the PiB positive group, as quantified by thin sliced 3D MRI and VBM software, was significantly more severe (p =0.0039) than in the PiB negative group. However, data histogram showed a vast overlap between the two groups. The area under the ROC curve (AUC) was 0.646. MMSE scores of patients in the amyloid negative and positive groups were also significantly different (p = 0.0028), and the AUC was 0.672. Thus, MTL atrophy could not reliably differentiate between amyloid positive and negative patients in a clinical setting, possibly due to the wide array of dementia-type diseases that exist other than AD.
  • Detection of sub-centimeter lesions using digital TOF-PET/CT system combined with Bayesian penalized likelihood reconstruction algorithm.
    Kenta Miwa, Kei Wagatsuma, Reo Nemoto, Masaki Masubuchi, Yuto Kamitaka, Tensho Yamao, Seiya Hiratsuka, Masashi Yamaguchi, Tokiya Yoshii, Rinya Kobayashi, Noriaki Miyaji, Kenji Ishii
    Annals of nuclear medicine, 34, 10, 762, 771, 2020年10月, [査読有り], [国内誌]
    英語, 研究論文(学術雑誌), OBJECTIVE: Many advances in PET/CT technology can potentially improve image quality and the ability to detect small lesions. A new digital TOF-PET/CT scanner based on silicon photomultipliers (SiPM) integrated with a Bayesian penalized likelihood (BPL) PET reconstruction algorithm (Q.Clear; GE Healthcare) has been introduced into clinical practice. The present study aimed to quantify the ability of a digital TOF-PET/CT scanner combined with BPL reconstruction to detect small lesions, and to determine the optimal penalization factor (β) in BPL to accurately detect such lesions. METHODS: All PET data were acquired from a NEMA body phantom using a Discovery MI (DMI) PET/CT system (GE Healthcare). The phantom included six spheres with diameters of 4, 5, 6, 8, 10, and 13 mm, and contained a background activity level of 5.3 kBq/mL, with target-to-background ratios (TBR) of 4:1 and 8:1. Images were reconstructed using a baseline OSEM algorithm, with OSEM + PSF, OSEM + TOF, OSEM + PSF + TOF, and BPL + PSF + TOF (β: 50-400). The matrix size was 192 × 192 and 384 × 384. Data acquired in 100-min list mode were re-binned into acquisition times ranging from 2 to 100 min. The quantitative accuracy and detectability of small hot spheres were evaluated by physical assessment of a recovery coefficient (RC) and a detectability index (DI), as well as visual assessment of PET images at each acquisition time. RESULTS: The RC and DI of sub-centimeter spheres were improved, because the digital TOF-PET/CT scanner has a larger TOF performance gain due to better timing resolution. The RC and DI were higher with BPL in sub-centimeter spheres, than with other OSEM-based types of reconstruction. The BPL for an 8-mm sphere overestimated uptake due to edge artifact overshoot induced by PSF modeling. The variability of RC and DI for acquisition times and TBR differed considerably according to β values. The RC for ~ 8-mm spheres were > 1 at β values between 50 and 100, but were close to 1 at β value of 200. The visual scores for β = 200 in BPL were maximal, whereas those for spheres that were ≥ 6 mm exceeded the criterion of 3. CONCLUSION: The BPL in the digital TOF-PET/CT scanner improved the quantitation and detectability of sub-centimeter spheres compared with OSEM-based reconstruction. Optimization of the β value in BPL might allow the detection of lesions ≤ 6 mm, although detectability depended on the TBR of lesions. A β value of 200 seemed optimal for detecting sub-centimeter lesions.
  • Optimization of a Bayesian penalized likelihood algorithm (Q.Clear) for 18F-NaF bone PET/CT images acquired over shorter durations using a custom-designed phantom.
    Tokiya Yoshii, Kenta Miwa, Masashi Yamaguchi, Kai Shimada, Kei Wagatsuma, Tensho Yamao, Yuto Kamitaka, Seiya Hiratsuka, Rinya Kobayashi, Hajime Ichikawa, Noriaki Miyaji, Tsuyoshi Miyazaki, Kenji Ishii
    EJNMMI physics, 7, 1, 56, 56, 2020年09月11日, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), BACKGROUND: The Bayesian penalized likelihood (BPL) algorithm Q.Clear (GE Healthcare) allows fully convergent iterative reconstruction that results in better image quality and quantitative accuracy, while limiting image noise. The present study aimed to optimize BPL reconstruction parameters for 18F-NaF PET/CT images and to determine the feasibility of 18F-NaF PET/CT image acquisition over shorter durations in clinical practice. METHODS: A custom-designed thoracic spine phantom consisting of several inserts, soft tissue, normal spine, and metastatic bone tumor, was scanned using a Discovery MI PET/CT scanner (GE Healthcare). The phantom allows optional adjustment of activity distribution, tumor size, and attenuation. We reconstructed PET images using OSEM + PSF + TOF (2 iterations, 17 subsets, and a 4-mm Gaussian filter), BPL + TOF (β = 200 to 700), and scan durations of 30-120 s. Signal-to-noise ratios (SNR), contrast, and coefficients of variance (CV) as image quality indicators were calculated, whereas the quantitative measures were recovery coefficients (RC) and RC linearity over a range of activity. We retrospectively analyzed images from five persons without bone metastases (male, n = 1; female, n = 4), then standardized uptake values (SUV), CV, and SNR at the 4th, 5th, and 6th thoracic vertebra were calculated in BPL + TOF (β = 400) images. RESULTS: The optimal reconstruction parameter of the BPL was β = 400 when images were acquired at 120 s/bed. At 90 s/bed, the BPL with a β value of 400 yielded 24% and 18% higher SNR and contrast, respectively, than OSEM (2 iterations; 120 s acquisitions). The BPL was superior to OSEM in terms of RC and the RC linearity over a range of activity, regardless of scan duration. The SUVmax were lower in BPL, than in OSEM. The CV and vertebral SNR in BPL were superior to those in OSEM. CONCLUSIONS: The optimal reconstruction parameters of 18F-NaF PET/CT images acquired over different durations were determined. The BPL can reduce PET acquisition to 90 s/bed in 18F-NaF PET/CT imaging. Our results suggest that BPL (β = 400) on SiPM-based TOF PET/CT scanner maintained high image quality and quantitative accuracy even for shorter acquisition durations.
  • 18F-sodium fluoride positron emission tomography may help determine better treatment for thigh pain after hip arthroplasty-A case report.
    Shinya Nakamura, Shigehito Uezono, Yuko Nagai, Masakazu Kanetaka, Kei Wagatsuma, Kenji Ishii, Takeshi Kumakawa, Kensuke Yasue, Yorito Anamizu, Fumiaki Tokimura, Tsuyoshi Miyazaki
    Clinical case reports, 8, 9, 1651, 1658, 2020年09月, [査読有り], [国際誌]
    英語, Thigh pain after hip arthroplasty is multifactorial; uncovering its etiology is paramount for optimal treatment. This is the first case where 18F-sodium fluoride positron emission tomography substantially helped in diagnosing the post-hip arthroplasty persistent thigh pain and appropriate treatment selection. This imaging modality warrants further study and more widespread application.
  • Longitudinal 18F-FDG Images in Patients With Alzheimer Disease Over More Than 9 Years From a Preclinical Stage.
    Kenji Ishibashi, Airin Onishi, Kei Wagatsuma, Yoshinori Fujiwara, Kenji Ishii
    Clinical nuclear medicine, 45, 4, e185-e189, 2020年04月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), BACKGROUND: Brain F-FDG uptake reportedly starts to decline more than 10 years before the onset of cognitive decline in dominantly inherited Alzheimer disease (AD). We compared longitudinal F-FDG images in sporadic AD to aging data from a large sample size to expand the current knowledge of F-FDG reduction for AD progression. METHODS: Participants comprised 2 individuals (subjects A and B at ages 65 and 68 years, respectively) and 107 control subjects (67.9 [SD, 4.9] years). Subject A underwent F-FDG PET a total of 8 times over 9 years from the preclinical to early dementia stages. Subject B underwent F-FDG PET a total of 11 times over 12 years from the preclinical to mild cognitive impairment stages. Control subjects underwent F-FDG PET twice over a mean follow-up period of 7.8 years. After placing the volume of interest on the AD-related hypometabolic regions, the longitudinal F-FDG images were compared among the subjects and control subjects. RESULTS: For the control group, the rate of F-FDG reduction was 2.2% per decade (ie, aging effects). The rates of F-FDG reduction were 9.41% over 9 years and 9.07% over 12 years in subjects A and B, respectively. We estimated that F-FDG uptake started to decrease 4 and 2 years before indications of memory loss in subjects A and B, respectively. CONCLUSIONS: The present study suggests that the time between the beginning of F-FDG reduction and the onset of cognitive decline may be shorter in elderly individuals with AD compared with the recently estimated period in dominantly inherited AD.
  • Metabolic Network Topology of Alzheimer's Disease and Dementia with Lewy Bodies Generated Using Fluorodeoxyglucose Positron Emission Tomography.
    Masamichi Imai, Mika Tanaka, Muneyuki Sakata, Kei Wagatsuma, Tetsuro Tago, Jun Toyohara, Renpei Sengoku, Yuji Nishina, Kazutomi Kanemaru, Kenji Ishibashi, Shigeo Murayama, Kenji Ishii
    Journal of Alzheimer's disease : JAD, 73, 1, 197, 207, 2020年01月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), BACKGROUND: Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) are often misdiagnosed with each other because of similar symptoms including progressive memory loss. The metabolic network topology that describes inter-regional metabolic connections can be generated using fluorodeoxyglucose positron emission tomography (FDG-PET) data with the graph-theoretical method. We hypothesized that different metabolic connectivity underlies the symptoms of AD patients, DLB patients, and cognitively normal (CN) individuals. OBJECTIVE: This study aimed to generate metabolic connectivity using FDG-PET data and assess the network topology to differentiate AD patients, DLB patients, and CN individuals. METHODS: This study included 45 AD patients, 18 DLB patients, and 142 CN controls. We analyzed FDG-PET data using the graph-theoretical method and generated the network topology in AD patients, DLB patients, and CN individuals. We statistically assessed the topology with global and nodal parameters. RESULTS: The whole metabolic network was preserved in CN; however, diffusely decreased connection was found in AD and partially but more deeply decreased connection was observed in DLB. The metabolic topology revealed that the right posterior cingulate and the left transverse temporal gyrus were significantly different between AD and DLB. CONCLUSION: The present findings indicate that metabolic connectivity decreased in both AD and DLB, compared with CN. DLB was characterized restricted but deeper stereotyped network disruption compared with AD. The right posterior cingulate and the left transverse temporal gyrus are significant regions in the metabolic connectivity for differentiating AD from DLB.
  • A pitfall of white matter reference regions used in [18F] florbetapir PET: a consideration of kinetics.
    Masashi Kameyama, Kenji Ishibash, Kei Wagatsuma, Jun Toyohara, Kenji Ishii
    Annals of nuclear medicine, 33, 11, 848, 854, 2019年11月, [査読有り], [国内誌]
    英語, 研究論文(学術雑誌), OBJECTIVE: Many studies have demonstrated the superiority of white matter (WM) reference regions (RR) in amyloid PET studies in comparison to cerebellar RR. However, the principle behind its improved measurement stability is yet to be elucidated. Our study aimed to determine the origin of WM stability; stability over cerebral blood flow and input function fluctuation or the greater statistical noise in the cerebellum due to its smaller size and its location in the axial periphery of the PET scanner bore. METHODS: We conducted simulations of [[Formula: see text]F] florbetapir using in-house program varying [Formula: see text] and input function, and adding statistical noise. RESULTS: Our simulations revealed that WM RR were more susceptible to CBF variation and input function fluctuation than cerebellar RR. WM RR did not gave superior measurement stability unless cerebellar statistical noise exceeded 4.55 times that in WM, a figure often surpassed in traditional amyloid PET studies. The greater statistical noise in cerebellum is likely the etiology for improved measurement stability of WM RR. CONCLUSION: A longitudinal [[Formula: see text]F] florbetapir PET study should be conducted with a long bore PET. It can also be hypothesized that a second scan with the cerebellum in the axial center of a 3D PET, using a cerebellar RR to calculate changes in tracer concentration may improve the measurement stability of longitudinal [[Formula: see text]F] florbetapir studies.
  • NaF PET assessment of bone metabolic changes around the femoral canal by intramedullary femoral alignment technique in total knee arthroplasty.
    Soichiro Kaneko, Masakazu Kanetaka, Kei Wagatsuma, Kenji Ishii, Yorito Anamizu, Fumiaki Tokimura, Tsuyoshi Miyazaki
    Clinical case reports, 7, 6, 1211, 1214, 2019年06月, [査読有り], [国際誌]
    英語, We used the NaF PET scan to assess osteometabolic changes around the distal half of the femoral canal by intramedullary (IM) drill for femoral IM guiding rod insertion in total knee arthroplasty. Gentle IM rod insertion and focused attention can minimize surgical stress-induced biological reaction of the femoral IM canal.
  • Pre-discard estimation of radioactivated materials in positron emission tomography cyclotron systems and concrete walls of a cyclotron vault.
    Kei Wagatsuma, Kiichi Ishiwata, Fumiyoshi Nobuhara, Iwane Koumura, Masayuki Kunugi, Keiichi Oda, Kenta Miwa, Jun Toyohara, Kenji Ishii
    Medical physics, 46, 5, 2457, 2467, 2019年05月, [査読有り], [筆頭著者, 責任著者], [国際誌]
    英語, 研究論文(学術雑誌), PURPOSE: The concrete vault, cyclotron body, and peripheral equipment in a cyclotron room become radioactivated by neutrons generated by operating an unshielded cyclotron. Radionuclides and the amounts of radioactivated materials must be identified before discarding a cyclotron system. The present study aimed to reduce the amounts of concrete from cyclotron vaults, as well as cyclotron components and peripheral equipment, that will be disposed of as radioactivated waste by clarifying the nature and quantity of radioactivated materials remaining in facilities after cyclotron operations have ceased. METHODS: Cylindrical concrete cores were bored into all four walls, ceiling, and floor of a room where a Cypris 370 cyclotron had been operated for 22.8 yr and then cooled for 40 months. The accelerated particles comprised protons and deuterons with constant energy of 18 and 10 MeV, respectively. The types and amounts of radionuclides in these cores, in 38 components of the cyclotron including the yoke, and in 13 pieces of equipment in the room, were determined by γ-ray spectrometry. Concentrations of radioactivity were also calculated using an updated version of Particle and Heavy Ion Transport System and DCHAIN-SP. Amounts of materials with both measured and calculated total radioactivity concentration (ΣD) of <0.1 Bq/g were identified as being nonradioactivated. RESULTS: The major radionuclides in the concrete were 60 Co and 152 Eu. The radioactivated concrete was distributed to a depth of <38 cm. Most cyclotron components and equipment were radioactivated by neutrons. The major radionuclides in cyclotron components and equipment were 54 Mn, 60 Co, and 65 Zn. A 33% volume of the yoke was regarded as nonradioactivated. CONCLUSIONS: The estimated amount of radioactivated waste in the concrete was about 70,000 kg (12.5% of the total concrete). Most components of the cyclotron except for the 33% volume of the yoke (20% of the cyclotron body), as well as most peripheral equipment in the room, were radioactivated. Part-by-part assessments of radioactive materials using measurements and calculations could distinguish nonradioactive from radioactive materials before they are discarded.
  • Occupancy of adenosine A2A receptors by istradefylline in patients with Parkinson's disease using 11C-preladenant PET.
    Kenji Ishibashi, Yoshiharu Miura, Kei Wagatsuma, Jun Toyohara, Kiichi Ishiwata, Kenji Ishii
    Neuropharmacology, 143, 106, 112, 2018年12月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), Istradefylline, an adenosine A2A receptor (A2AR) antagonist, is effective as an adjunct to levodopa and can alleviate "off" time and motor symptoms in patients with Parkinson's disease (PD). The present study aimed to calculate occupancy rates of A2ARs by administrating istradefylline 20 mg or 40 mg, which is the currently approved dose for PD in Japan. Additionally, A2AR availability was compared between patients with PD and healthy controls. Ten patients with PD under levodopa therapy and six age-matched healthy controls were included. The patients underwent a total of two 11C-preladenant positron emission tomography scans before and after the administration of istradefylline 20 mg or 40 mg (both n = 5). Binding potential (BPND) was calculated to estimate A2AR availability in the ventral striatum, caudate, and putamen. Maximal A2AR occupancy and ED50 were estimated by modeling the dose-occupancy curves. All patients were around the middle stage of PD, and their characteristics were clinically heterogeneous. Maximal A2AR occupancy and ED50 were 93.5% and 28.6 mg in the ventral striatum, 69.5% and 10.8 mg in the caudate, and 66.8% and 14.8 mg in the putamen, respectively. There were no significant differences in BPND values in the ventral striatum (P = 0.42), caudate (P = 0.72), and putamen (P = 0.43) between the PD and control groups. In conclusion, the present study shows that istradefylline binds to A2ARs dose-dependently. A sufficient occupancy of A2ARs could be obtained by administrating the approved dose of istradefylline.
  • Validation of scatter limitation correction to eliminate scatter correction error in oxygen-15 gas-inhalation positron emission tomography images.
    Kei Wagatsuma, Keiichi Oda, Muneyuki Sakata, Motoki Inaji, Kenta Miwa, Masayuki Sasaki, Jun Toyohara, Kenji Ishii
    Nuclear medicine communications, 39, 10, 936, 944, 2018年10月, [査読有り], [筆頭著者], [国際誌]
    英語, 研究論文(学術雑誌), OBJECTIVE: High levels of radioactivity inside a facemask cause scatter correction (SC) errors that appear as photopenic artifacts on quantitative oxygen-15 (O) gas-inhalation positron emission tomography (PET) images. The present study aimed to validate the ability of scatter limitation correction (SLC) to eliminate SC errors in O gas-inhalation PET images acquired from patients and a phantom. MATERIALS AND METHODS: We analyzed the SC errors in phantom images and calculated parametric images of the cerebral blood flow (CBF), cerebral blood volume, oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2). Phantoms comprised a cylinder and paper with radioactivity to simulate a facemask during (O)O2 gas inhalation. Parametric images were calculated from O gas-inhalation PET images of ten participants. All PET data were reconstructed using conventional SC as model-based SC and SLC. Images acquired from the phantoms and parametric images were assessed visually and quantitatively in the presence and absence of SC error. RESULTS: SC error was evident in images derived from the paper phantom and at the slice level of the cerebellum in CBF, OEF, and CMRO2 images. The radioactivity concentration in the cylindrical phantom with the paper phantom significantly improved with SLC. The SLC also increased the quantitative indices of CBF, OEF, and CMRO2 by 23.8, 42.2, and 44.4%, respectively. CONCLUSION: SLC visually eliminated the SC error and increased the quantitative parameters on O gas-inhalation images derived from a phantom and from patients.
  • Unique Angiographic Appearances of Moyamoya Disease Detected with 3-Dimensional Rotational Digital Subtraction Angiography Imaging Showing the Hemodynamic Status.
    Jun Karakama, Tadashi Nariai, Shoko Hara, Shihori Hayashi, Kazutaka Sumita, Motoki Inaji, Yoji Tanaka, Kei Wagatsuma, Kenji Ishii, Shigeru Nemoto, Taketoshi Maehara
    Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association, 27, 8, 2147, 2157, W.B. Saunders, 2018年08月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • Multicenter study of quantitative PET system harmonization using NIST-traceable 68Ge/68Ga cross-calibration kit.
    Kenta Miwa, Kei Wagatsuma, Takashi Iimori, Koichi Sawada, Takashi Kamiya, Minoru Sakurai, Noriaki Miyaji, Taisuke Murata, Eisuke Sato
    Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB), 52, 98, 103, 2018年08月, [査読有り], [筆頭著者], [国際誌]
    英語, 研究論文(学術雑誌), PURPOSE: The present study aimed to define the errors in SUV and demonstrate the feasibility of SUV harmonization among contemporary PET/CT scanners using a novel National Institute of Standards and Technology (NIST)-traceable 68Ge/68Ga source as the reference standard. METHODS: We used 68Ge/68Ga dose calibrator and PET sources made with same batch of 68Ge/68Ga embedded in epoxy that is traceable to the NIST standard. Bias in the amount of radioactivity and the radioactive concentrations measured by the dose calibrators and PET/CT scanners, respectively, was determined at five Japanese sites. We adjusted optimal dial setting of the dose calibrators and PET reconstruction parameters to close the actual amount of radioactivity and the radioactive concentration, respectively, of the NIST-traceable 68Ge/68Ga sources to harmonize SUV. Errors in SUV before and after harmonization were then calculated at each site. RESULTS: The average bias in the amount of radioactivity and the radioactive concentrations measured by dose calibrator and PET scanner was -4.94% and -12.22%, respectively, before, and -0.14% and -4.81%, respectively, after harmonization. Corresponding averaged errors in SUV measured under clinical conditions were underestimated by 7.66%, but improved by -4.70% under optimal conditions. CONCLUSION: Our proposed method using an NIST-traceable 68Ge/68Ga source identified bias in values obtained using dose calibrators and PET scanners, and reduced SUV variability to within 5% across different models of PET scanners at five sites. Our protocol using a standard source has considerable potential for harmonizing the SUV when contemporary PET scanners are involved in multicenter studies.
  • Bayesian penalized-likelihood reconstruction algorithm suppresses edge artifacts in PET reconstruction based on point-spread-function.
    Shotaro Yamaguchi, Kei Wagatsuma, Kenta Miwa, Kenji Ishii, Kazumasa Inoue, Masahiro Fukushi
    Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB), 47, 73, 79, 2018年03月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), PURPOSE: The Bayesian penalized-likelihood reconstruction algorithm (BPL), Q.Clear, uses relative difference penalty as a regularization function to control image noise and the degree of edge-preservation in PET images. The present study aimed to determine the effects of suppression on edge artifacts due to point-spread-function (PSF) correction using a Q.Clear. METHODS: Spheres of a cylindrical phantom contained a background of 5.3 kBq/mL of [18F]FDG and sphere-to-background ratios (SBR) of 16, 8, 4 and 2. The background also contained water and spheres containing 21.2 kBq/mL of [18F]FDG as non-background. All data were acquired using a Discovery PET/CT 710 and were reconstructed using three-dimensional ordered-subset expectation maximization with time-of-flight (TOF) and PSF correction (3D-OSEM), and Q.Clear with TOF (BPL). We investigated β-values of 200-800 using BPL. The PET images were analyzed using visual assessment and profile curves, edge variability and contrast recovery coefficients were measured. RESULTS: The 38- and 27-mm spheres were surrounded by higher radioactivity concentration when reconstructed with 3D-OSEM as opposed to BPL, which suppressed edge artifacts. Images of 10-mm spheres had sharper overshoot at high SBR and non-background when reconstructed with BPL. Although contrast recovery coefficients of 10-mm spheres in BPL decreased as a function of increasing β, higher penalty parameter decreased the overshoot. CONCLUSIONS: BPL is a feasible method for the suppression of edge artifacts of PSF correction, although this depends on SBR and sphere size. Overshoot associated with BPL caused overestimation in small spheres at high SBR. Higher penalty parameter in BPL can suppress overshoot more effectively.
  • Response of Cerebral Blood Flow and Blood Pressure to Dynamic Exercise: A Study Using PET.
    Mikio Hiura, Tadashi Nariai, Muneyuki Sakata, Akitaka Muta, Kenji Ishibashi, Kei Wagatsuma, Tetsuro Tago, Jun Toyohara, Kenji Ishii, Taketoshi Maehara
    International journal of sports medicine, 39, 3, 181, 188, Georg Thieme Verlag, 2018年02月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • Natural Postoperative Bone Metabolic Changes after Total Knee Arthroplasty Determined by Positron Emission Tomography Scans
    Masakazu Kanetaka, Soichiro Kaneko, Kei Wagatsuma, Kenji Ishii, Kimiteru Ito, Shinya Nakamura, Hiroshi Hamaji, Yukimasa Yamato, Yorito Anamizu, Fumiaki Tokimura, Tsuyoshi Miyazaki
    Open Journal of Orthopedics, 08, 12, 443, 457, Scientific Research Publishing, Inc., 2018年, [査読有り]
    英語, 研究論文(学術雑誌)
  • Dynamic Exercise Elicits Dissociated Changes Between Tissue Oxygenation and Cerebral Blood Flow in the Prefrontal Cortex: A Study Using NIRS and PET.
    Mikio Hiura, Tadashi Nariai, Katsumi Takahashi, Akitaka Muta, Muneyuki Sakata, Kenji Ishibashi, Jun Toyohara, Kei Wagatsuma, Tetsuro Tago, Kenji Ishii, Taketoshi Maehara
    Advances in experimental medicine and biology, 1072, 269, 274, 2018年, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), Neuronal activity causes changes in both cerebral metabolic rate of oxygen (CMRO2) and cerebral blood flow (CBF). Since the relationship between tissue oxygenation and regional CBF (rCBF) during exercise has not been elucidated, we compared the data obtained using near-infrared spectroscopy (NIRS) and rCBF examined using positron emission tomography (PET). Participants in this study comprised 26 healthy young men. Changes in concentration of oxygenated hemoglobin (ΔO2Hb) and deoxygenated hemoglobin (ΔHHb) in the prefrontal cortex (PFC) were measured using NIRS continuously during a 15-min bout of the constant-load low-intensity cycling exercise (n = 14). Under the same protocol as the NIRS study, rCBF was measured using H215O and PET by the autoradiographic method at baseline (Rest) and at 3 min (Ex1) and 13 min (Ex2) after starting exercise (n = 12). As systematic factors influenced by exercise, heart rate, end-tidal pressure of carbon dioxide (PETCO2) and blood pressure (BP) were monitored. For each region investigated by NIRS, rCBF was analyzed quantitatively using PET-MRI co-registered standardized images. Despite inter-individual differences, changing patterns of ΔO2Hb and ΔHHb in the PFC were similar between channels. Significant main effects for time point were identified in ΔO2Hb, ΔHHb and changes in rCBF. While rCBF increased from rest, ΔO2Hb was not changed at Ex1. Conversely, rCBF was unchanged from rest but ΔO2Hb was significantly increased at Ex2. Fluctuations of PETCO2 and BP evoked by exercise were not in accordance with changes in ΔO2Hb, ΔHHb and rCBF, while BP may affect the forehead skin blood flow. Given that NIRS data are a mixture of skin and brain effects, our results suggest that CMRO2 may differ between the phases in a bout of dynamic exercise. The present study indicates the utility of NIRS to examine the relationship between CMRO2 and rCBF during exercise.
  • Revision with Locking Plate and Sliding Inlay Bone Graft for Hypertrophic Nonunion after Combined Treatment of Ender Nails and Teriparatide for Atypical Femoral Stress Fracture A Unique Case Report.               
    Koshiishi A, Hamaji H, Wada Y, Ito K, Wagatsuma K, Ishii K, Kanetaka M, Kaneko S, Uezono S, Shoda N, Anamizu Y, Tokimura F, Miyazaki T
    J Orthopedics Rheumatol, 4, 2, 1, 6, 2017年12月, [査読有り]
    英語
  • Assessment of safety, efficacy, and dosimetry of a novel 18-kDa translocator protein ligand, [11C]CB184, in healthy human volunteers.
    Muneyuki Sakata, Kenji Ishibashi, Masamichi Imai, Kei Wagatsuma, Kenji Ishii, Kentaro Hatano, Kiichi Ishiwata, Jun Toyohara
    EJNMMI research, 7, 1, 26, 26, 2017年12月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • Effects of a novel tungsten-impregnated rubber neck shield on the quality of cerebral images acquired using 15O-labeled gas.
    Kei Wagatsuma, Keiichi Oda, Kenta Miwa, Motoki Inaji, Muneyuki Sakata, Jun Toyohara, Kiichi Ishiwata, Masayuki Sasaki, Kenji Ishii
    Radiological physics and technology, 10, 4, 422, 430, Springer Tokyo, 2017年12月, [査読有り], [筆頭著者], [国内誌]
    英語, 研究論文(学術雑誌)
  • Optimization of a shorter variable-acquisition time for legs to achieve true whole-body PET/CT images.
    Takuro Umeda, Kenta Miwa, Taisuke Murata, Noriaki Miyaji, Kei Wagatsuma, Kazuki Motegi, Takashi Terauchi, Mitsuru Koizumi
    Australasian physical & engineering sciences in medicine, 40, 4, 861, 868, 2017年12月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • Changes in brain amyloid-β accumulation after donepezil administration.
    Ishibashi K, Miura Y, Wagatsuma K, Ishiwata K, Ishii K
    Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia, 45, 328, 329, 2017年11月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • Comparison between new-generation SiPM-based and conventional PMT-based TOF-PET/CT.
    Kei Wagatsuma, Kenta Miwa, Muneyuki Sakata, Keiichi Oda, Haruka Ono, Masashi Kameyama, Jun Toyohara, Kenji Ishii
    Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB), 42, 203, 210, 2017年10月, [査読有り], [筆頭著者], [国際誌]
    英語, 研究論文(学術雑誌)
  • Initial Evaluation of an Adenosine A2A Receptor Ligand, 11C-Preladenant, in Healthy Human Subjects.
    Muneyuki Sakata, Kenji Ishibashi, Masamichi Imai, Kei Wagatsuma, Kenji Ishii, Xiaoyun Zhou, Erik F J de Vries, Philip H Elsinga, Kiichi Ishiwata, Jun Toyohara
    Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 58, 9, 1464, 1470, 2017年09月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • Age and gender effects of 11C-ITMM binding to metabotropic glutamate receptor type 1 in healthy human participants.
    Muneyuki Sakata, Jun Toyohara, Kenji Ishibashi, Kei Wagatsuma, Kenji Ishii, Ming-Rong Zhang, Kiichi Ishiwata
    Neurobiology of aging, 55, 72, 77, 2017年07月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • Comparison of 3 Devices for Automated Infusion of Positron-Emitting Radiotracers.
    Noriaki Miyaji, Kenta Miwa, Kei Wagatsuma, Taisuke Murata, Takuro Umeda, Takashi Terauchi, Mitsuru Koizumi
    Journal of nuclear medicine technology, 45, 2, 91, 95, Society of Nuclear Medicine Inc., 2017年06月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • 骨SPECT 定量における異なる校正用線源の相互校正の精度
    宮司典明, 三輪建太, 茂木一樹, 梅田拓朗, 我妻慧, 深井翔平, 滝口智洋, 寺内隆司, 小泉満
    日本放射線技術学会雑誌, 73, 6, 443, 450, 2017年, [査読有り], [国内誌]
    日本語, PURPOSE: Several cross-calibration schemes have been proposed to produce quantitative values in bone SPECT imaging. Differences in the radionuclide sources and geometric conditions can decrease the accuracy of cross-calibration factor (CCF). The present study aimed to validate the effects of calibration schemes using different sources under various geometric conditions. METHODS: Temporal variations as well as variations in acquisition counts and the shapes of 57Co standard and 99mTc point sources and a 99mTc disk source were determined. The effects of the geometric conditions of the source-to-camera distance (SCD) and lateral distance on the CCF were investigated by moving the camera or source away from the origin. The system planar sensitivity of NEMA incorporated into a Symbia Intevo SPECT/CT device (Siemens®) was defined as reference values. RESULTS: The temporal variation in CCF using the 57Co source was relatively stable within the range of 0.7% to 2.3%, whereas the 99mTc source ranged from 2.7% to 7.3%. In terms of source shape, the 57Co standard point source was the most stable. Both SCD and lateral distance decreased as a function of distance from the origin. Errors in the geometric condition were higher for the 57Co standard point source than the 99mTc disk source. CONCLUSIONS: Different calibration schemes influenced the reliability of quantitative values. The 57Co standard point source was stable over a long period, and this helped to maintain the quality of quantitative SPECT/CT imaging data. The CCF accuracy of the 99mTc source decreased depending on the preparative method. The method of calibration for quantitative SPECT should be immediately standardized to eliminate uncertainty.
  • 呼吸同期PET/CTを用いた横隔膜境界における肉眼的腫瘍体積の算出能の評価
    中澤脩人, 中澤脩人, 梅田拓朗, 宮司典明, 三輪建太, 我妻慧, 茂木一樹, 滝口智洋, 寺内隆司, 小泉満, 臼井桂介, 笹井啓資
    日本放射線技術学会雑誌, 73, 8, 617, 625, 2017年, [査読有り], [国内誌]
    日本語, OBJECTIVE: The present study aimed to clarify gross tumor volume (GTV) contouring accuracy at the diaphragm boundary using respiratory-gated PET/CT. METHODS: The lung/diaphragm boundary was simulated using a phantom containing 18F solution (10.6 kBq/mL). Tumors were simulated using spheres (diameter, 11-38 mm) containing 18F and located at the positions of the lungs and liver. The tumor background ratios (TBR) were 2, 4, and 8. The phantom was moved from the superior to inferior direction with a 20-mm motion displacement at 3.6 s intervals. The recovery coefficient (RC), volume RC (VRC), and standardized uptake value (SUV) threshold were calculated using stationary, non-gated (3D), and gated (4D) PET/CT. RESULTS: In lung cancer simulation, RC and VRC in 3D PET images were, respectively, underestimated and overestimated in smaller tumors, whereas both improved in 4D PET images regardless of tumor size and TBR. The optimal SUV threshold was about 30% in 4D PET images. In liver cancer simulation, RC and VRC were, respectively, underestimated and overestimated in smaller tumors, and when the TBR was lower, but both improved in 4D PET images when tumors were >17 mm and the TBR was >4. The optimal SUV threshold tended to depend on the TBR. CONCLUSIONS: The contouring accuracy of GTV was improved by considering TBR and using an optimal SUV threshold acquired from 4D PET images.
  • 223Raイメージングにおける異なるコリメータとエネルギーウインドウの設定が総合感度および総合空間分解能に与える影響
    梅田拓朗, 宮司典明, 中澤脩人, 三輪建太, 我妻慧, 茂木一樹, 滝口智洋, 小泉満
    日本放射線技術学会雑誌, 73, 11, 1132, 1139, 2017年, [査読有り]
  • Evaluation of spatial dependence of point spread function-based PET reconstruction using a traceable point-like 22Na source.
    Taisuke Murata, Kenta Miwa, Noriaki Miyaji, Kei Wagatsuma, Tomoyuki Hasegawa, Keiichi Oda, Takuro Umeda, Takashi Iimori, Yoshitada Masuda, Takashi Terauchi, Mitsuru Koizumi
    EJNMMI physics, 3, 1, 26, 26, Springer International Publishing, 2016年12月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • Preclinical and first-in-man studies of [ (11)C]CB184 for imaging the 18-kDa translocator protein by positron emission tomography.
    Jun Toyohara, Muneyuki Sakata, Kentaro Hatano, Shuichi Yanai, Shogo Endo, Kenji Ishibashi, Kei Wagatsuma, Kenji Ishii, Kiichi Ishiwata
    Annals of nuclear medicine, 30, 8, 534, 43, 2016年10月, [査読有り], [国内誌]
    英語, 研究論文(学術雑誌)
  • Alteration of the regional cerebral glucose metabolism in healthy subjects by glucose loading.
    Kenji Ishibashi, Kei Wagatsuma, Kiichi Ishiwata, Kenji Ishii
    Human brain mapping, 37, 8, 2823, 32, 2016年08月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • Report of a nationwide survey on actual administered radioactivities of radiopharmaceuticals for diagnostic reference levels in Japan.
    Hiroshi Watanabe, Kazunari Ishii, Makoto Hosono, Etsuko Imabayashi, Koichiro Abe, Masayuki Inubushi, Kazuko Ohno, Yasuhiro Magata, Kinya Ono, Kei Kikuchi, Kei Wagatsuma, Tadashi Takase, Kyoko Saito, Yasuyuki Takahashi
    Annals of nuclear medicine, 30, 6, 435, 44, 2016年07月, [査読有り], [国内誌]
    英語, 研究論文(学術雑誌)
  • Comparison of dosimetry between PET/CT and PET alone using (11)C-ITMM.
    Kimiteru Ito, Muneyuki Sakata, Keiichi Oda, Kei Wagatsuma, Jun Toyohara, Kenji Ishibashi, Kenji Ishii, Kiichi Ishiwata
    Australasian physical & engineering sciences in medicine, 39, 1, 177, 86, 2016年03月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • Evaluation of scatter limitation correction: a new method of correcting photopenic artifacts caused by patient motion during whole-body PET/CT imaging.
    Kenta Miwa, Takuro Umeda, Taisuke Murata, Kei Wagatsuma, Noriaki Miyaji, Takashi Terauchi, Mitsuru Koizumi, Masayuki Sasaki
    Nuclear medicine communications, 37, 2, 147, 54, 2016年02月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • 肝臓腫瘍に対する呼吸同期PET/CTの非線形レジストレーション処理の有用性
    我妻慧, 大澤達史, 横川直樹, 三輪建太, 織田圭一, 織田圭一, 工藤善朗, 海野泰, 伊藤公輝, 伊藤公輝, 石井賢二
    日本放射線技術学会雑誌, 72, 11, 1067, 1073, 2016年, [査読有り], [筆頭著者], [国内誌]
    日本語, OBJECTIVE: The present study aimed to determine the qualitative and quantitative accuracy of the Q.Freeze algorithm in PET/CT images of liver tumors. METHODS: A body phantom and hot spheres representing liver tumors contained 5.3 and 21.2 kBq/mL of a solution containing 18F radioactivity, respectively. The phantoms were moved in the superior-inferior direction at a motion displacement of 20 mm. Conventional respiratory-gated (RG) and Q.Freeze images were sorted into 6, 10, and 13 phase-groups. The SUVave was calculated from the background of the body phantom, and the SUVmax was determined from the hot spheres of the liver tumors. Three patients with four liver tumors were also clinically assessed by whole-body and RG PET. The RG and Q.Freeze images derived from the clinical study were also sorted into 6, 10 and 13 phase-groups. Liver signal-to-noise ratio (SNR) and SUVmax were determined from the RG and Q.Freeze clinical images. RESULTS: The SUVave of Q.Freeze images was the same as those derived from the body phantom using RG. The liver SNR improved with Q.Freeze, and the SUVsmax was not overestimated when Q.Freeze was applied in both the phantom and clinical studies. Q.Freeze did not degrade the liver SNR and SUVmax even though the phase number was larger. CONCLUSIONS: Q.Freeze delivered qualitative and quantitative motion correction than conventional RG imaging even in 10-phase groups.
  • Evaluation of a revised version of computer-assisted diagnosis system, BONENAVI version 2.1.7, for bone scintigraphy in cancer patients.
    Mitsuru Koizumi, Noriaki Miyaji, Taisuke Murata, Kazuki Motegi, Kenta Miwa, Masamichi Koyama, Takashi Terauchi, Kei Wagatsuma, Kazunori Kawakami, Jens Richter
    Annals of nuclear medicine, 29, 8, 659, 65, 2015年10月, [査読有り], [国内誌]
    英語, 研究論文(学術雑誌)
  • Evaluation of a computer-assisted diagnosis system, BONENAVI version 2, for bone scintigraphy in cancer patients in a routine clinical setting.
    Mitsuru Koizumi, Kei Wagatsuma, Noriaki Miyaji, Taisuke Murata, Kenta Miwa, Tomohiro Takiguchi, Tomoko Makino, Masamichi Koyama
    Annals of nuclear medicine, 29, 2, 138, 48, 2015年02月, [査読有り], [国内誌]
    英語, 研究論文(学術雑誌)
  • 位相呼吸同期PET/CT撮像によるPET定量値の改善率の検討
    三輪建太, 三輪建太, 我妻慧, 梅田拓朗, 宮司典明, 村田泰輔, 大澤敦, 滝口智洋, 小泉満, 佐々木雅之
    日本放射線技術学会雑誌, 70, 11, 1235, 42, (公社)日本放射線技術学会, 2014年11月, [査読有り], [国内誌]
    日本語
  • Optimal radiation shielding for beta and bremsstrahlung radiation emitted by (89)Sr and (90)Y: validation by empirical approach and Monte Carlo simulations.
    Taisuke Murata, Kenta Miwa, Fumiyasu Matsubayashi, Kei Wagatsuma, Kenta Akimoto, Toshioh Fujibuchi, Noriaki Miyaji, Tomohiro Takiguchi, Masayuki Sasaki, Mitsuru Koizumi
    Annals of nuclear medicine, 28, 7, 617, 22, 2014年08月, [査読有り], [国内誌]
    英語, 研究論文(学術雑誌)
  • FDG uptake heterogeneity evaluated by fractal analysis improves the differential diagnosis of pulmonary nodules.
    Kenta Miwa, Masayuki Inubushi, Kei Wagatsuma, Michinobu Nagao, Taisuke Murata, Masamichi Koyama, Mitsuru Koizumi, Masayuki Sasaki
    European journal of radiology, 83, 4, 715, 9, 2014年04月, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌)
  • 薬剤供給システムの異なる18F-FDG PET/CT 検査における臨床画像の比較
    我妻慧, 三輪建太, 宮司典明, 村田泰輔, 梅田拓朗, 大澤敦, 滝口智洋, 小泉満
    日本放射線技術学会雑誌, 70, 4, 339, 45, 2014年04月, [査読有り], [筆頭著者], [国内誌]
    日本語, OBJECTIVE: PET images are affected by scanner model, reconstruction conditions, injected dose, scan duration, patient health status and FDG radiopharmaceutical supply systems. The present study compares images of 40 patients using commercial and in-house FDG systems with one PET scanner (Aquiduo). METHODS: The PET images were evaluated using the physical indexes of NECpatient, NECdensity and SNRliver proposed by the Japanese guidelines for oncological FDG-PET/CT, and by visual assessment. RESULTS: There were no significant differences in the physical indexes between PET images generated using commercial and in-house FDG. The physical indexes were also acceptable according to the recommended Japanese guidelines. NECdensity was higher when a higher dose/body weight of commercial FDG was injected (correlation coefficient: r=0.576, p<0.001) and lower when BMI was lower and in-house FDG was injected (r=-0.786, p<0.0001). These results suggest that scan duration should be increased if the injected dose of commercial FDG/body weight is <5.5 MBq/kg, and if individuals with BMI >21.4 kg/m(2) are injected with in-house FDG. CONCLUSIONS: Scan duration should be varied depending on FDG supply systems to ensure more accurate image quality and quantitative values during evaluations of response to therapy and prognostic prediction.
  • ガンマカメラ用57Co面線源の基礎的検討と日常点検への利用
    我妻慧, 三輪建太, 秋本健太, 對間博之, 宮司典明, 梅田拓朗, 村田泰輔, 滝口智洋, 小泉満
    日本放射線技術学会雑誌, 70, 2, 148, 53, 2014年02月, [査読有り], [筆頭著者], [国内誌]
    日本語, Quality control (QC) detects changes in the performance of gamma cameras that could adversely affect interpretations of clinical studies. We used plate and sheet (57)Co flood sources to measure extrinsic uniformity during daily QC. Each source, when placed on the top of a collimated detector, allowed the acquisition of uniform images from both detectors, thus reducing the amount of time needed to perform daily QC. No serious problems with the gamma camera system were revealed by visual checks, and changes in detector sensitivity were rapidly determined by observing daily variations in the measured values of extrinsic uniformity. Furthermore, (57)Co flood sources confer advantages in that they shorten the time required for preparation of flood sources and reduce the consequent exposure of medical staff to radiation.
  • トレーサブル68Ge/68Ga標準線源を用いた PET用ドーズキャリブレータの精度管理
    宮司典明, 三輪建太, 我妻慧, 梅田拓朗, 村田泰輔, 滝口智洋, 小泉満
    日本放射線技術学会雑誌, 69, 12, 1379, 86, 2013年12月, [査読有り], [国内誌]
    日本語, OBJECTIVES: Accurate calibration of dose calibrators (DC) is required for quantitative positron emission tomography (PET) studies to generate meaningful information. Values measured by DC depend not only on the radioactive nuclide but also the environment where measurements are taken. Therefore, DC must be calibrated at each location. The present study aimed to determine appropriate calibration values, and evaluate the performance of DC using a traceable (68)Ge/(68)Ga calibration source that is available as a surrogate (18)F source. METHODS: We used a (68)Ge/(68)Ga calibration source to determine the optimal DC value for measuring (18)F activity in the operating environment. Variations in sensitivity and geometry as well as measurement uncertainty were evaluated using the (68)Ge/(68)Ga source. We adopted the criteria of the Guide for the expression of uncertainty in measurement (GUM) to evaluate DC performance. RESULTS: Although the manufacturer's recommended (18)F calibration number for the CRC-25PET is 480, we found that the optimal number was 482. Over a period of one year, the sensitivity of the DC varied <0.1%, and the expanded uncertainty of DC measurements was 2.2%. CONCLUSION: Measurements of the certified activity of a traceable national standard were corrected, and the uncertainty of measurements as well as the accuracy of a DC were determined. Calibration numbers for DC should be regularly determined using (68)Ge/(68)Ga calibration sources at each location to ensure the most accurate results.
  • Validation of novel calibration scheme with traceable point-like (22)Na sources on six types of PET scanners.
    Tomoyuki Hasegawa, Keiichi Oda, Yasuhiro Wada, Toshiaki Sasaki, Yasushi Sato, Takahiro Yamada, Mikio Matsumoto, Hideo Murayama, Kei Kikuchi, Hiroki Miyatake, Yutaka Abe, Kenta Miwa, Kenta Akimoto, Kei Wagatsuma
    Annals of nuclear medicine, 27, 4, 346, 54, 2013年05月, [査読有り], [国内誌]
    英語, 研究論文(学術雑誌)
  • 三次元PET収集における被写体断面積と画質の関係
    大澤敦, 三輪建太, 我妻慧, 滝口智洋, 田村慎太郎, 秋本健太
    日本放射線技術学会雑誌, 68, 12, 1600, 7, 2012年, [査読有り], [国内誌]
    日本語, The image quality in (18)FDG PET/CT often degrades as the body size increases. The purpose of this study was to evaluate the relationship between image quality and the body size using original phantoms of variable cross-sectional areas in PET/CT. We produced five water phantoms with different cross-sectional areas. The long axis of phantom was 925 mm, and the cross-sectional area was from 324 to 1189 cm(2). These phantoms with the sphere (diameter 10 mm) were filled with (18)F-FDG solution. The radioactivity concentration of background in the phantom was 1.37, 2.73, 4.09 and 5.46 kBq/mL. The scanning duration was 30 min in list mode acquisition for each measurement. Background variability (N(10 mm)), noise equivalent count rates (NECR(phantom)), hot sphere contrast (Q(H,10 mm)) as physical evaluation and visual score of sphere detection were measured, respectively. The relationship between image quality and the various cross-sectional areas was also analyzed under the above-mentioned conditions. As cross-sectional area increased, NECR(phantom) progressively decreased. Furthermore, as cross-sectional area increased, N(10 mm) increased and Q(H,10 mm) decreased. Image quality became degraded as body weight increased because noise and contrast contributed to image quality. The visual score of sphere detection deteriorated in high background radioactivity concentration because a false positive detection in cross-sectional area of the phantom increased. However, additional increases in scanning periods could improve the visual score. We assessed tendencies in the relationship between image quality and body size in PET/CT. Our results showed that time adjustment was more effective than dose adjustment for stable image quality of heavier patients in terms of the large cross-sectional area.
  • CT-transmissionの呼吸管理がPET/CTの融合精度に与える影響-600人を対象とした標準呼気と自由呼吸の比較-
    大澤敦, 滝口智洋, 田村慎太郎, 大橋聖, 三輪建太, 秋本健太, 我妻慧
    日本放射線技術学会雑誌, 66, 7, 743, 8, 2010年07月, [査読有り], [国内誌]
    日本語, Image misregistration can occur in fusion PET/CT, because of motion artifacts caused by the management of respiration. The standard imaging protocol of the CT component of PET/CT is normal expiration (NormExp) or free breathing (FB). The objective of this study was to compare NormExp and FB for the optimal breathing protocol for PET/CT scans. A total of 600 consecutive patients were examined using lutetium oxyorthosilicate (LSO)-based PET/CT. CT was acquired during NormExp (i.e., the level reached when the patient exhaled without forcing expiration and then held the breath) in 300 patients and during FB in 300 patients. The profile of liver measured along body axis was assessed. The distance of profile centers between the PET image and the CT image was measured. The misalignment between profile centers (PET) and profile centers (CT) was compared between NormExp and FB using the histogram of patients. An F test was used to test if the variances of two misalignments are equal. Next, the relationship between misalignment and age was evaluated in two managements of respiration. There was no significant difference between NormExp and FB in the histogram. However, significant misalignments (>10 cm) were found with NormExp. Patient age may have influenced the mismatch. FB is recommended for geriatric patients during acquisition of attenuation correction CT data sets.

その他活動・業績

書籍等出版物

  • 放射線医療技術叢書(38)アーチファクト・アトラス(MRI,CT,SPECT,PET)               
    三輪建太, 我妻慧, 越智伸司, 孫田恵一, 村田泰輔, 第4章 PET画像に発生するアーチファクト
    日本放射線技術学会出版委員会, 2021年03月, [分担執筆]
  • 新核医学技術総論[臨床編]
    日本核医学技術学会, 第2節 糖代謝イメージング,第3章 PET検査,第Ⅱ部 脳神経
    山代印刷出版部, 2020年03月, 9784991020124, 2冊, 日本語, [分担執筆]
  • 新核医学技術総論[技術編]
    日本核医学技術学会, 第2章 PET装置,第Ⅲ部 装置の性能評価と安全実施上の保守点検
    山代印刷出版部, 2020年03月, 9784991020124, 2冊, 日本語, [分担執筆]
  • 超実践マニュアル核医学
    VERSUS研究会, 對間, 博之, 飯森, 隆志, 甲谷, 理温, I-10 PET 脳
    医療科学社, 2016年04月, 9784860034771, xix, 488p, 日本語
  • 初学者のための核医学実験入門 = ABC book of experiment in nuclear medicine for beginners               
    日本放射線技術学会核医学部会, 3.5 脳PET撮像実験
    日本放射線技術学会出版委員会, 2016年, [分担執筆]

講演・口頭発表等

  • 認知症PET検査と核医学技術               
    我妻慧
    日本診療放射線技師連盟主催 第9回定例勉強会, 2025年04月23日, 日本語, 口頭発表(招待・特別)
    2025年04月23日 - 2025年04月23日, [招待講演]
  • 一歩先のアミロイドPET画像の作り方               
    我妻慧
    第28回Neurology SPECT定量検討会, 2024年11月16日, 日本語, 口頭発表(基調)
    [招待講演]
  • アミロイドPET検査の撮像技術               
    我妻慧
    第1回日本放射線医療技術大会, 2024年11月01日, 日本語, 口頭発表(基調)
    2024年10月31日 - 2024年11月03日
  • 押さえておきたいアミロイドPET検査の技術的ポイント               
    我妻慧
    第65回多摩核医学技術検討会, 2024年10月11日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    [招待講演]
  • アミロイドPET検査のコツ               
    我妻慧
    GE HealthCare PET Technical Seminar 2024 in 北陸, 2024年06月29日, 日本語
    2024年06月29日 - 2024年06月29日
  • より良いアミロイドPET撮像のために大切なこと               
    我妻慧
    第83回日本医学放射線学会総会, 2024年04月11日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2024年04月11日 - 2024年04月14日
  • アミロイドPET撮像施設認証の受審経験               
    我妻慧
    第12回 New Clear Imaging Conference, 2024年01月20日, 日本語, 口頭発表(招待・特別)
    2024年01月20日 - 2024年01月20日
  • StarGuideの画像再構成技術の検討               
    我妻慧
    第1回StarGuide Consprtium, 2024年02月22日, 日本語, その他
    2024年02月22日 - 2024年
  • 診療放射線技師の仕事と放射線について               
    我妻慧
    2023年度KGMメディカルセミナー, 2023年11月21日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2023年11月21日 - 2023年11月21日, [招待講演]
  • アミロイドPETとタウPETの概要と撮像               
    我妻慧
    第43回日本核医学技術学会総会学術大会, 2023年11月18日, 日本語, 口頭発表(招待・特別)
    2023年11月16日 - 2023年11月18日, [招待講演]
  • JSNMT国際奨励賞受賞講演               
    我妻慧
    第43回日本核医学技術学会総会学術大会, 2023年11月17日, 日本語, 口頭発表(招待・特別)
    2023年11月16日 - 2023年11月18日
  • PET核医学エキスパートセミナー 基礎1 PET装置のQA/QC               
    我妻慧
    第23回日本核医学会春季大会, 2023年04月, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2023年04月26日 - 2023年06月01日
  • PET研修セミナー 臨床PET検査法 PET画像処理               
    我妻慧
    第23回日本核医学会春季大会, 2023年04月, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2023年04月26日 - 2023年06月01日
  • 神経変性疾患を捉える脳PET撮像技術               
    我妻慧
    第79回日本放射線技術学会総会学術大会総会学術大会, 2023年04月15日, 日本語, シンポジウム・ワークショップパネル(指名)
    2023年04月13日 - 2023年04月16日
  • アミロイドPETイメージングの撮像技術               
    我妻慧
    神奈川核医学研究会第436回定例研究会, 2022年12月15日, 日本語, 口頭発表(招待・特別)
    2022年12月15日 - 2022年12月15日
  • アミロイド・タウPET撮像の技術的なトピックス               
    我妻慧
    第19回脳核医学画像解析研究会, 2022年09月17日, 日本語, 口頭発表(招待・特別)
  • アミロイドPETイメージングの撮像技術               
    我妻慧
    第42回日本核医学技術学会総会学術大会, 2022年09月09日, 日本語, シンポジウム・ワークショップパネル(指名)
    2022年09月09日 - 2022年09月11日
  • 論文執筆に挑戦しよう               
    我妻慧
    研究発表トレーニングキャンプ 2022, 2022年09月04日, 日本語, 口頭発表(招待・特別)
    2022年09月02日 - 2022年09月04日
  • 最新PET装置と技術利用               
    我妻慧
    第51回 なにわRIセミナー, 2022年07月20日, 日本語, 口頭発表(招待・特別)
    2022年07月20日 - 2022年07月20日
  • PET核医学エキスパートセミナー 基礎1 PET装置のQA/QC               
    我妻慧
    第22回日本核医学会春季大会, 2022年05月, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2022年05月07日 - 2022年06月01日
  • PET研修セミナー 臨床PET検査法 PET画像処理               
    我妻慧
    第22回日本核医学会春季大会, 2022年05月, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2022年05月07日 - 2022年06月01日
  • あらためてPETのQA/QCを考えよう               
    我妻慧
    第50回神奈川PET・SPECT研究会-腫瘍-, 2022年05月28日, 日本語, 口頭発表(招待・特別)
    2022年05月28日 - 2022年05月28日
  • ファントムの作成方法について               
    我妻慧
    第143回東京支部セミナー, 2022年03月12日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
  • SiPM-PET/CT、徹底解説!!               
    我妻慧
    第24回New Clear Technologyカンファレンス, 2022年02月26日, 日本語, 口頭発表(招待・特別)
  • 英語論文雑誌の紹介               
    我妻慧
    第265回東京支部技術フォーラム 国際化推進フォーラム『Let's try!! 英語論文』, 2022年01月22日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
  • 徹底解剖、SiPM-PET/CT装置               
    我妻慧
    PETサマーセミナー2021in下呂, 2021年08月27日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2021年08月27日 - 2021年08月29日
  • PET研修セミナー 臨床PET検査法 PET画像処理               
    我妻慧
    第21回 日本核医学会春季大会, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2021年05月07日 - 2021年05月31日
  • ファントムの作成方法について               
    我妻慧
    第134回東京支部セミナー, 2021年03月13日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2021年03月13日 - 2021年03月13日
  • 核医学検査機器の保守点検の重要性               
    我妻慧
    第40回日本核医学技術学会総会学術大会, 2020年11月14日, 日本語, 口頭発表(基調)
    2020年11月12日 - 2020年11月14日
  • 明日からはじめるための認知症PET検査技術               
    我妻慧
    第15回21世紀山口核医学セミナー, 2020年02月06日, 日本語, 口頭発表(招待・特別)
    2020年02月06日 - 2020年02月06日, [招待講演]
  • アミロイド陽電子断層撮像(PET)の臨床使用へ向けた撮像条件の検討               
    我妻慧, 石橋賢士, 坂田宗之, 多胡哲郎, 豊原潤, 石井賢二
    首都大バイオコンファレンス2019, 2019年11月15日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2019年11月15日 - 2019年11月15日
  • SiPM-PET/CT装置『Discovery MI』の臨床的な有用性               
    我妻慧
    第39回日本核医学技術学会総会学術大会, 2019年11月01日, 日本語, シンポジウム・ワークショップパネル(指名)
    2019年11月01日 - 2019年11月03日
  • アミロイド・タウPETにおける撮像技術               
    我妻慧
    PETサマーセミナー2019in福島, 2019年08月24日, 日本語, シンポジウム・ワークショップパネル(指名)
    2019年08月23日 - 2019年08月25日
  • 学術研究論文を読むための基礎講座〜研究活動のススメ〜               
    我妻慧
    国立病院関東甲信越放射線技師会「第52回学術研究会」, 2019年05月25日, 日本語, 口頭発表(招待・特別)
    2019年05月25日 - 2019年05月25日, [招待講演]
  • アミロイドPET研究における技術的なトピックス               
    我妻慧
    第914回放射線診療研究会, 2019年02月04日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2019年02月04日 - 2019年02月04日, [招待講演]
  • 国際化について一緒に考えよう!「スタンフォード大学海外研修で得たモノ,そして現在・・・」               
    我妻慧
    日本放射線技術学会関東・東京支部合同研究発表大会2018, 2018年12月16日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2018年12月15日 - 2018年12月16日
  • PET定量測定の意義と技術的注意点               
    我妻慧
    第13回中国四国医用画像カンファレンス, 2018年06月30日, 日本語, 口頭発表(招待・特別)
    2018年06月30日 - 2018年06月30日, [招待講演]
  • デジタルPETの可能性と有用性               
    我妻慧
    第5回首都圏PETユーザーズミーティング, 2018年06月16日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2018年06月16日 - 2018年06月16日
  • 診療放射線技師のこれから               
    我妻慧
    第1回駒澤大学診療放射線研究会, 2018年05月26日, 日本語, シンポジウム・ワークショップパネル(指名)
    2018年05月26日 - 2018年05月26日
  • ここまでわかる脳機能画像,PETを用いた脳機能計測               
    我妻慧, 石橋賢士, 石井賢二
    第35回日本核医学技術学会関東地方会総会, 2018年05月12日, 日本語, シンポジウム・ワークショップパネル(指名)
    2018年05月12日 - 2018年05月13日, [招待講演]
  • 核医学実験の核心に迫る:PET実験編 3.脳PET領域での研究法               
    我妻慧
    第74回日本放射線技術学会総会学術大会, 2018年04月14日, 日本語, シンポジウム・ワークショップパネル(指名)
    2018年04月12日 - 2018年04月15日
  • 半導体(SiPM)PET/CT装置の初期検討と有用性               
    我妻慧
    第27回関東甲信越核医学画像処理研究会, 2018年02月03日, 日本語, 口頭発表(招待・特別)
    2018年02月03日 - 2018年02月03日, [招待講演]
  • SiPM-PET/CTの性能評価と初期検討               
    我妻慧
    第906回放射線診療研究会, 2017年11月06日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2017年11月06日 - 2017年11月06日, [招待講演]
  • アミロイドPETに求められるもの               
    我妻慧
    PETサマーセミナー2017in奈良, 2017年08月26日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2017年08月25日 - 2017年08月27日
  • Discover MIの使用経験〜脳領域における技師の立場から〜               
    我妻慧
    PETサマーセミナー2017in奈良, 2017年08月25日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2017年08月25日 - 2017年08月27日
  • SiPM-PET/CT Discovery MIの性能評価と基礎検討               
    我妻慧
    PETサマーセミナー2017in奈良, 2017年08月25日, 日本語, 口頭発表(招待・特別)
    2017年08月25日 - 2017年08月27日, [招待講演]
  • 核医学技術におけるPETの最前線               
    我妻慧
    第220回東京支部技術フォーラム, 2017年07月07日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2017年07月07日 - 2017年07月07日
  • 表示付認証機器を用いたSPECTのQC・QA               
    我妻慧
    第13回Molecular Imaging Technologist Conference, 2016年12月09日, 日本語, 口頭発表(招待・特別)
    2016年12月09日 - 2016年12月09日, [招待講演]
  • 技術的側面におけるアミロイドPETイメージングの基礎のキソ               
    我妻慧
    第56回日本核医学会学術総会, 2016年11月04日, 日本語, 口頭発表(招待・特別)
    2016年11月03日 - 2016年11月05日, [招待講演]
  • 臨床応用を目指したPET薬剤の次世代化,シンポジウム[薬剤]次世代の核医学イメージング剤               
    豊原潤, 多胡哲郎, 坂田宗之, 石橋賢士, 我妻慧, 石渡喜一, 石井賢二
    第56回日本核医学会学術総会, 2016年11月04日, 日本語, シンポジウム・ワークショップパネル(指名)
    2016年11月03日 - 2016年11月05日
  • 認知症被検者の医療安全〜診療放射線技師の立場から〜               
    我妻慧
    第56回日本核医学会学術総会, 2016年11月03日, 日本語, シンポジウム・ワークショップパネル(指名)
    2016年11月03日 - 2016年11月05日
  • ファントムを用いた脳PETイメージングの技術的検討               
    我妻慧
    第14回脳核医学画像解析研究会, 2016年09月10日, 日本語, 口頭発表(招待・特別)
    2016年09月10日 - 2016年09月10日, [招待講演]
  • PETにおける定量               
    我妻慧
    第32回インフォーマルミーティング, 2016年01月09日, 日本語, 公開講演,セミナー,チュートリアル,講習,講義等
    2016年01月09日 - 2016年01月09日

担当経験のある科目_授業

  • 核医科学特論               
    福島県立医科大学大学院
    2025年04月 - 現在
  • 放射線診断・核医学基礎物理学               
    北海道大学大学院
    2025年04月 - 現在
  • 放射化学実験               
    北海道大学
    2025年04月 - 現在
  • 核医学検査技術学               
    北海道大学
    2025年04月 - 現在
  • 核医学機器工学概論               
    北海道大学
    2025年04月 - 現在
  • 核医学検査技術学実習               
    北海道大学
    2025年04月 - 現在
  • 核医学概論               
    北海道大学
    2025年04月 - 現在
  • 放射化学               
    北海道大学
    2025年04月 - 現在
  • 放射線基礎講義II               
    北里大学
    2024年04月 - 2025年07月
  • 放射線安全管理学               
    北里大学大学院
    2023年04月 - 2025年07月
  • 核医学技術学・放射化学実習               
    北里大学
    2021年05月 - 2025年07月
  • 放射線管理学               
    北里大学
    2021年05月 - 2025年07月
  • 放射化学               
    北里大学
    2021年05月 - 2025年07月
  • 実践臨床画像学               
    北里大学
    2024年04月 - 2025年03月
  • 医療安全管理学               
    北里大学
    2024年04月 - 2025年03月
  • 卒業研究               
    北里大学
    2022年04月 - 2025年03月
  • 医用画像処理Ⅱ               
    北里大学
    2022年04月 - 2025年03月
  • 核医学技術学I               
    北里大学
    2022年04月 - 2025年03月
  • 放射線臨床病態薬理学               
    北里大学
    2022年04月 - 2025年03月
  • 診療放射線技術科学概論               
    北里大学
    2022年04月 - 2025年03月
  • 診療放射線技術科学総合演習               
    北里大学
    2021年05月 - 2025年03月
  • 放射線関係法規               
    北里大学
    2021年05月 - 2025年03月
  • 放射線管理学・計測学実習               
    北里大学
    2021年05月 - 2025年03月
  • 放射線科学(実習含)               
    北里大学
    2021年05月 - 2025年03月
  • 放射線管理学演習               
    北里大学
    2021年05月 - 2024年03月
  • 放射化学演習               
    北里大学
    2021年05月 - 2023年03月
  • 放射線科学               
    北里大学
    2021年05月 - 2023年03月
  • ポジトロン科学特論               
    東京都立大学大学院
    2018年04月 - 2020年03月
  • 核医学検査技術学               
    東洋公衆衛生学院
    2020年 - 2020年
  • 応用機器工学               
    駒澤大学
    2015年 - 2019年

所属学協会

  • 米国核医学会               
  • 日本アイソトープ協会               
  • 日本核医学会               
  • 日本核医学技術学会               
  • 日本放射線技術学会               

共同研究・競争的資金等の研究課題

  • タウPET標準化を目指した新しいファントムの開発と全国展開
    科学研究費助成事業 若手研究
    2023年04月 - 2026年03月
    我妻 慧
    日本学術振興会, 若手研究, 北里大学, 研究代表者, 23K14875
  • 深層学習を用いた超解像度技術のタウPET 画像への応用               
    北里大学医療衛生学部 2024年度特別研究費
    2024年06月 - 2025年03月
    三輪建太, 山尾天翔
    北里大学医療衛生学部, 北里大学医療衛生学部, 研究代表者
  • タウPET 専用ファントムの解析手法の確立               
    「放射線災害・医科学研究拠点」共同利用・共同研究
    2024年04月 - 2025年03月
    三輪建太
    放射線災害・医科学研究拠点, 2024年度「放射線災害・医科学研究拠点」共同利用・共同研究, 北里大学医療衛生学部, 研究代表者
  • 機械学習を用いた高解像度技術のタウPET 画像への応用               
    北里大学医療衛生学部 2023年度特別研究費
    2023年06月 - 2024年03月
    我妻慧、小川恵美悠、三輪建太
    北里大学医療衛生学部, 北里大学, 研究代表者
  • タウPET 専用ファントムの解析手法の確立
    「放射線災害・医科学研究拠点」共同利用・共同研究
    2023年04月 - 2024年03月
    三輪建太
    放射線災害・医科学研究拠点, 2023年度「放射線災害・医科学研究拠点」共同利用・共同研究, 北里大学医療衛生学部, 研究代表者
  • アルツハイマー型認知症を対象としたタウPETの標準化手法の確立
    科学研究費助成事業 若手研究
    2020年04月01日 - 2023年03月31日
    我妻 慧
    2021年度、タウPET専用のファントムとして、分解能、画像ノイズ、画像コントラストを一度の撮像で評価が可能なタウPET専用のファントムを作成した。既存の評価ファントムでは画像コントラストと画像ノイズを一度に評価をすることができなかったが、本申請で作成したファントムでこれらの評価指標を一度に評価が可能となった。2020年度に明らかにしたタウPETを模擬する放射能条件は既存のファントムを考慮して決定したため、本年度に作成したタウPET専用のファントムに対応して放射能条件を微調整してタウPET専用のファントムの放射能条件を明らかにした。タウPET専用のファントムの均一部分を使用して画像ノイズを測定することができ、タウPET専用のファントムの画像ノイズは既存のファントムの評価結果と遜色のない結果であった。画像コントラストおよび分解能はタウPET専用のファントムの脳を模擬した部分を使用する。また、本研究では2021年に欧州の多施設研究の脳PET撮像の標準化で使用されている脳PETの定量性を示す指標であるリカバリ係数を採用することとした。タウPET専用のファントムの画像の画像コントラストと定量性は既存のファントムの結果と比較して過小評価されていることがわかった。この結果から、タウPET専用のファントムで解析に使用している手法が既存のファントムをベースに作成しているため、ファントム自体の違いによる影響が出ていると考えた。2022年度はこの解析方法の最適化を目指す。タウPET専用ファントムの脳を模擬した部分の画像は脳の構造をよく再現していることがわかった。アルツハイマー病ではタウ蛋白病変が側頭葉内側から沈着する。タウPET専用ファントムの脳を模擬した部分は側頭葉に相当する。本研究によってアルツハイマー病に伴うタウ蛋白の沈着を的確にとらえ、早期発見および重症度評価の可能性が示された。
    日本学術振興会, 若手研究, 地方独立行政法人東京都健康長寿医療センター(東京都健康長寿医療センター研究所), 20K16747
  • アルツハイマー病診断のための標準的タウPETイメージングの解析法の開発               
    2022年度特別研究費
    2022年06月 - 2023年03月
    北里大学医療衛生学部, 2022年度特別研究費, 北里大学医療衛生学部, 研究代表者
  • タウPET 専用ファントムの解析手法の確立               
    「放射線災害・医科学研究拠点」共同利用・共同研究
    2022年04月 - 2023年03月
    三輪建太
    放射線災害・医科学研究拠点, 2022年度「放射線災害・医科学研究拠点」共同利用・共同研究, 北里大学医療衛生学部, 研究代表者
  • あらゆるタウPET薬剤に対応した標準的撮像法と新しい客観的評価法の開発               
    令和2年度理事長奨励研究
    2020年06月 - 2021年03月
    坂田宗之
    東京都健康長寿医療センター, 令和2年度理事長奨励研究費, 東京都健康長寿医療センター, 研究代表者
  • アデノシンA2A受容体の分子イメージング:ファーストインヒューマン研究
    科学研究費助成事業 基盤研究(B)
    2016年04月01日 - 2019年03月31日
    石渡 喜一, 坂田 宗之, 鷺野谷 利幸, 豊原 潤, 石橋 賢士, 三品 雅洋, 片山 宗一, 久保 仁, 水野 泰章, 石井 賢二, 我妻 慧
    アデノシンA2A受容体を画像化する新規PET薬剤11C標識プレラデナント(PLN)の初期臨床試験を実施した。成人健常者で検査の安全性と被曝線量評価をし、目的の受容体を計測することが示された。
    これをパーキンソン病患者に応用したところ、健常者に比較して未治療パーキンソン病で受容体密度の優位な変化は認められなかったが、左右差に着目すると尾状核頭部は健常者より左右差が大きかった。また、治療量のイストラデフェリンの線条体アデノシンA2A受容体占拠率は、最大で約70%に達した。これらの結果は、PLN-PETは脳の病態生理学的研究の新しいツールになることが示している。
    日本学術振興会, 基盤研究(B), 一般財団法人脳神経疾患研究所, 16H05396
  • 脳FDG-PETおよびMRIと機械学習を用いた高精度な認知症自動鑑別診断
    科学研究費助成事業 基盤研究(C)
    2015年04月01日 - 2018年03月31日
    坂田 宗之, 石井 賢二, 我妻 慧, 木村 裕一
    認知症の診断や対策には、原因疾患の鑑別診断が不可欠である。本研究では、機械学習を用いてFDG-PETおよびMRIを入力とした認知症の鑑別を自動で行うシステムを構築した。FDG-PETの糖代謝低下とMRIにおける脳の萎縮を表す画像から特徴量を抽出し、サポートベクターマシンで学習する仕組みで、アルツハイマー型、前頭側頭型、レビー小体型の各原因疾患と健常群をそれぞれ自動で識別し、加えて疾患の重症度や進行度を表す客観的な指標を提示することで臨床の鑑別診断を支援する。
    日本学術振興会, 基盤研究(C), 地方独立行政法人東京都健康長寿医療センター(東京都健康長寿医療センター研究所), 15K09982
  • 代謝型グルタミン酸受容体1型の分子イメージング:ファーストインヒューマン研究
    科学研究費助成事業 基盤研究(B)
    2012年04月01日 - 2016年03月31日
    石渡 喜一, 日浦 幹夫, 三品 雅洋, 坂田 宗之, 石橋 賢志, 石井 賢二, 豊原 潤, 織田 圭一, 我妻 慧, 張 明栄
    代謝型グルタミン酸受容体1型サブタイプを画像化する新規PET薬剤[11C]ITMMの初期臨床試験を実施した。成人健常者で検査の安全性と被曝線量評価をし、目的の受容体を計測することが示され、[11C]ITMM-PETは脳の病態生理学的研究の新しいツールになることが示された。
    これを神経変性疾患患者に応用し、脊髄小脳変性症とパーキンソン病では脳局所での受容体の低下が認められ、アルツハイマー病やてんかんでも予備的ではあるが受容体の変化が示唆された。
    日本学術振興会, 基盤研究(B), 地方独立行政法人東京都健康長寿医療センター(東京都健康長寿医療センター研究所), 24390298

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