Researcher Database

KUDO Nobuki
Faculty of Information Science and Technology Bioengineering and Bioinformatics Bioengineering
Associate Professor

Researcher Profile and Settings

Affiliation

  • Faculty of Information Science and Technology Bioengineering and Bioinformatics Bioengineering

Job Title

    Associate Professor

Degree

  • MS and PhD degree in Biomedical Engineering in 1984 and 1987, Hokkaido University

E-mail

  • kudo@ist.hokudai.ac.jp

URL

Research Interests

  • Biomedical UltrasoundBiomedical Optics   

Research Areas

  • Biomedical engineering / Medical systems
  • Science education/Educational technology / Educational technology
  • Biomedical engineering / Biomedical engineering/Biological material science
  • Biomedical engineering / Medical systems

Academic & Professional Experience

  • 1995 - 1997     Research Associate,Faculty of Engineering, Hokkaido University
  • 1997 - 2004     Research Associate,Graduate School of Engineering, Hokkaido University
  • 2004 - 2007     Research Associate

Education

  •        - 1984  Hokkaido University  japan
  •        - 1987  Hokkaido University  japan
  •        - 1982  Hokkaido University  Faculty of Engineering  japan

Association Memberships

  • IEEE   

Research Activities

Published Papers

Conference Activities & Talks

MISC

  • KUDO Nobuki  39-  (6)  567  -568  2012/11   [Not refereed] [Not invited]
  • KUDO Nobuki  38-  (6)  623  -624  2011/11   [Not refereed] [Not invited]
  • Obara Hiroki, Kudo Nobuki, Shimizu Koichi  IEICE technical report. Ultrasonics  111-  (88)  31  -35  2011/06   [Not refereed] [Not invited]  
    Recently, there has been considerable interest in sonoporation, a technique to transduct drugs or genes into cells by ultrasound exposure. In typical studies of sonoporation using cultured cells, the cells and microbubbles are suspended in a culture dish with medium, and exposed to continuous ultrasound waves. In this situation, reflection of ultrasound at a medium-air interface and dish walls produces complex acoustic fields with various standing waves. In this study, the pressure fields of therapeutic ultrasound in a small chamber are visualized using a newly proposed technique called image-subtraction Schlieren. Observation results revealed that brightness of visualized fields is doubled in the presence of reflection and that brightness is decreased adjacent to the chamber wall. It was also confirmed that perturbation of water surface by acoustic streaming causes decrease in pressure amplitudes at antinodes. The linear relation found between brightness of the Schlieren images and acoustic pressure indicates the importance of the image-subtraction Schlieren technique for dosimetry of complex acoustic fields generated inside small chambers.
  • OKUYAMA Manabu, KUDO Nobuki, SHIMIZU Koichi  IEICE technical report. ME and bio cybernetics  111-  (84)  7  -12  2011/06   [Not refereed] [Not invited]  
    Sonoporation is a promising technique that temporally increases membrane permeability by exposure of cells to ultrasound. We have been studying a sonoporation technique that uses short-pulsed ultrasound and reported that this exposure condition also can initiate sonoporation effects in the case with microbubbles attached to the cells. In order to clarify the roles of the bubbles for this technique, it is essential to study sonoporation phenomena under control of the size and position of bubbles adjacent cells, which is difficult to achieve by our conventional experimental system. In this study, we developed optical tweezes system that can trap micron-sized bubbles of an ultrasound contrast agent. A spatial liquid modulation device was used to generate a phase hologram for producing doughnut-shaped light beam (Laguerre-Gaussian beam). In the results, it was shown that the tweezers can generate the transverse trapping force of about 20 pN for a bubble of 2.5μm in radius using 1-W laser light. It was also confirmed that the tweezers can manipulate contrast-agent bubbles of 0.5-2.5μm in radius, which are widely used for sonoporation studies.
  • LI Xin, KUDO Nobuki, SHIMIZU Koichi, KURIKI Shinya  2011-  (1)  71  -76  2011/01   [Not refereed] [Not invited]
  • LI Xin, KUDO Nobuki, SHIMIZU Koichi, KURIKI Shinya  IEICE technical report. ME and bio cybernetics  110-  (399)  71  -76  2011/01   [Not refereed] [Not invited]  
    A magnetic detection technique was devised to noninvasively detect the tip position of the nasal feeding tube that delivers liquid diet to the patient's stomach through a transnasal tube. We have designed an AC magnetic susceptibility measurement system that consists of an excitation coil and a pair of differential detection coils. To attain practical sensitivity, a technique to maximize the excitation field at a specific depth in the patient's body has been newly developed. In experimental analyses, the effectiveness of the developed technique was verified.
  • KUDO Nobuki, SHIMIZU Koichi  IEICE technical report. ME and bio cybernetics  110-  (111)  13  -16  2010/06   [Not refereed] [Not invited]  
    A suspension of microbubbles of about one micron in diameter is now widely used as a contrast agent for diagnostic ultrasound and as an enhancer for therapeutic ultrasound. In this study, five types of gas-encapsulated liposomes (bubble liposomes) were produced and their stability was studied under static and dynamic pressure conditions. Five types of phosphatidylcholine, DOPC, POPC, DMPC, DPPC and DSPC, with different transition temperatures between liquidcrystalline and gel phases in the range of -22℃ to +55℃, were used as a main component of the liposomes. Static stability of these bubbles was evaluated by observations of temporal change in turbidity of their suspension, and dynamic stability was evaluated by measurements of pressure-dependent ultrasound transmission. The results showed that both stabilities have strong dependence on temperature of the bubble suspensions, suggesting that phase of the shell material is one of the main parameters for determining bubble stabilities. Bubbles with shells in gel phase have higher stability under the condition of exposure to ultrasound, suggesting that the intact shell in this phase can be restored immediately after bubble oscillation.
  • Okada Kengo, Kudo Nobuki, Hassan Mariame A., Kondo Takashi, Yamamoto Katsuyuki  Proceedings of Symposium on Ultrasonic Electronics  (29)  419  -420  2008/11   [Not refereed] [Not invited]
  • KIBE Ryuta, KEK Khai Jun, KUDO Nobuki, YAMAMOTO Katsuyuki  2007-  (36)  13  -16  2007/06   [Not refereed] [Not invited]
  • SUZUKI Ryosuke, SOSEKHA Ly, KUDO Nobuki, YAMAMOTO Katsuyuki  2007-  (36)  17  -20  2007/06   [Not refereed] [Not invited]
  • KIBE Ryuta, KEK Khai Jun, KUDO Nobuki, YAMAMOTO Katsuyuki, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  107-  (126)  13  -16  2007/06   [Not refereed] [Not invited]  
    We have been developing a device for imaging muscle oxygenation using spatially resolved spectroscopy. To validate the measurement reliability of the device, we previously used tissue-mimicking liquid phantoms using red blood cells. However, validation could not be sufficiently performed due to unstable optical properties and poor reproducibility of the liquid phantoms. Therefore, we constructed plastic phantoms that mimic the optical properties of backscattered light from muscles with the aim of establishing a more stable and simple method for validation. Clear plastic was used as the base resin, and the concentrations of absorber and scatterer were adjusted accordingly to mimic the absorption and scattering of light in muscle and adipose tissues. Values of absorption coefficient μ'_s and reduced scatter coefficient μ'_s of the muscle tissue phantoms (μ_a=0.019-0.047 mm^<-1>, μ'_s=0.53-0.68 mm^<-1>) and adipose tissue phantoms (μ_a=0.0002-0.0052 mm^<-1>, μ'_s=0.83-1.05 mm^<-1>) were measured using time-resolved spectroscopy, and the values showed good agreement with those of actual tissues.
  • SUZUKI Ryosuke, SOSEKHA Ly, KUDO Nobuki, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  107-  (126)  17  -20  2007/06   [Not refereed] [Not invited]  
    We have proposed a novel simple method for visualizing acoustic fields of diagnostic pulsed ultrasound without using a conventional Schlieren optical system. Based on the proposed method, we have developed an experimental system and have evaluated its practical usefulness experimentally. In this study, we developed a new low-cost system using a consumer digital camera and an inexpensive laser diode. We also successfully visualized an acoustic field of a diagnostic ultrasound probe using this system. The results indicate the possibility of applying the proposed method to routine inspection of ultrasound probe function in a hospital.
  • MIYAKAWA Takahiro, KEK Khai Jun, KUDO Nobuki, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  106-  (127)  21  -24  2006/06   [Not refereed] [Not invited]  
    Near-infrared spectroscopy (NIRS) is a useful technique for noninvasive and real-time measurement of muscle oxygenation. In this study, we constructed a continuous-wave NIRS (CWS) instrument with high temporal resolution. Using the instrument, we measured the changes in local muscle oxygen consumption rate (Vo_2) during exercise with rapid arterial occlusion method. We also investigated the exercise- (continuous and intermittent isometric contraction exercises) and measurement site-dependent (forearm flexor and tibialis anterior muscles) differences in local Vo_2. The results show that local Vo_2 could be measured almost instantaneously and that the exercise and measurement site-dependent differences in local Vo_2 could be clearly distinguished using NIRS.
  • MIYASHITA Hideki, KUDO Nobuki, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  106-  (127)  5  -8  2006/06   [Not refereed] [Not invited]  
    Previously, we proposed a novel simple Schlieren method that eliminates the use of complex optical system for visualizing acoustic fields of diagnostic pulsed ultrasound. Based on the proposed method, we developed an experiment system and evaluated its applicability experimentally. In this study, we successfully visualized the acoustic field of high-intensity focused ultrasound (HIFU) transducer with the developed experiment system. The input power of the transducer was changed in the range of 10-100W, and the visualized acoustic fields showed typical non-linear distortion at higher input powers. The results show that the proposed simple Schlieren method is useful for evaluating an acoustic field of a HIFU transducer.
  • YOKOYAMA Goya, OKADA Kengo, KUDO Nobuki, KAWAHARA Koichi, YAMAMOTO Katsuyuki  2005-  (7)  21  -24  2005/06   [Not refereed] [Not invited]
  • IKEBUCHI Masayasu, OKADA Kengo, KUDO Nobuki, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  105-  (122)  25  -28  2005/06   [Not refereed] [Not invited]  
    Sonoporation is a technique that increases drug uptake of cells using ultrasound exposure. Recently, it has been shown that exposure of cells to pulsed ultrasound with microbubbles attached to the cells can improve efficiency of sonoporation; however, the mechanisms of this phenomenon have not yet been revealed. In this study, we carried out sonoporation of cultivated endothelial cells using pulsed ultrasound in the presence of bubbles, and the cell slight damage and repair was evaluated using fluorescence and scanning electron microscopes. Based on the results, we concluded that mechanical damage of cell membrane induced by mechanical bubble effects can enhance cell membrane permeability and that damage of cell membrane is repaired within 20 seconds.
  • YOKOYAMA Goya, OKADA Kengo, KUDO Nobuki, KAWAHARA Koichi, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  105-  (122)  21  -24  2005/06   [Not refereed] [Not invited]  
    Recent study in human volunteers has shown that exposure to ultrasound during contrast echocardiography can cause premature ventricular contractions (PVCs). To elucidate its mechanism, we carried out experiments using cultivated cardiac myocytes and investigated the dependence of PVC production on timing and pressure amplitude of ultrasound irradiation with and without microbubbles. In the results, PVCs were observed only in the period after the end of myocyte contraction, suggesting that this time-dependent phenomenon was caused by a refractory period of myocytes. Threshold pressure to produce PVCs decreased in the presence of microbubbles attached to the cells, reflecting that the ultrasound-induced bubble behavior can give mechanical stress to myocytes greater than that produced by exposure to ultrasound without microbubbles.
  • IKEBUCHI Masayasu, OKADA Kengo, KUDO Nobuki, YAMAMOTO Katsuyuki  105-  (122)  25  -28  2005/06   [Not refereed] [Not invited]
  • OUCHI Hiroyuki, KUDO Nobuki, YAMAMOTO Katsuyuki, SEKIMIZU Hidemasa  IEICE technical report. Ultrasonics  104-  (142)  9  -12  2004/06   [Not refereed] [Not invited]  
    A new Schlieren method for visualizing an acoustic field of pulsed ultrasound was proposed, and a system was developed to evaluate the validity of the proposed method by visualizing an acoustic field of a focused ultrasound field of diagnostic frequency range. A conventional Schlieren optical system is not used in the developed system. The system consists of a short-pulsed laser, a CCD camera with a wide dynamic range, and a PC that processes images captured by the CCD camera. In the proposed method, extraction of light diffracted by ultrasound is carried out by subtraction of images captured with and without ultrasound exposure. The usefulness of the developed system was confirmed by experiments in which acoustic fields of a 5-MHz focused transducer and 20-MHz non-focused transducer were visualized.
  • YONEYAMA Satoko, KUDO Nobuki, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  104-  (129)  5  -8  2004/06   [Not refereed] [Not invited]  
    In recent years, many studies on muscle oxygenation measurement using near-infrared spectroscopy (NIRS) have been conducted. However, it is difficult to estimate the tissue metabolic kinetics from NIRS measurements because many factors are related to muscle energy metabolism. In this study, we made a model of muscle metabolism that was consisted of an ATP production system and an oxygen diffusion system. The former was modeled with an aerobic system, phosphocreatine system and glycolysis, and the latter was modeled with blood and tissue compartments. Steady and transient responses to exercise were simulated and compared with experimental results. It was strongly suggested that temporal responses of NIRS mainly reflect changes in oxygenation of hemoglobin and myoglobin at high and low tissue oxygenation levels, respectively.
  • MAEKAWA Kota, KUDO Nobuki, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  104-  (129)  9  -12  2004/06   [Not refereed] [Not invited]  
    Near-infrared spectroscopy (NIRS) is a useful technique for noninvasive and real-time measurement of tissue oxygenation. However, it is difficult to measure independently the oxygen concentrations of hemoglobin (Hb) and myoglobin (Mb) because the absorption spectrum of Hb is almost the same as that of Mb. In this study, we performed a basic study on measurement of oxygen saturation in skeletal muscles using microspectrophotometry, aiming to find the contribution rates of Hb and Mb to NIRS measurements. Oxygen saturation of small vessels of about 30μm in diameter was able to be measured in the mesentery and cremaster muscles of small animals. However, the conventional microspectrophotometry using transmitted light is restricted to measurement for thin tissues. Therefore, a reflective lighting technique that is applicable to thick skeletal muscles was also studied.
  • OKADA Kengo, KUDO Nobuki, NIWA Koichi, WADA Shigeo, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  103-  (133)  49  -54  2003/06   [Not refereed] [Not invited]  
    Sonoporation is a technique that increases drag uptake of cells by ultrasound exposure. Ultrasound exposure of continuous wave has beens mainly used in this technique, and it is well known that existence of microbubbles around cells improves efficiency of sonoporation. Recent studies have shown that cell permeability can be increased by exposure of pulsed ultrasound with microbubbles; however, the mechanism of is not yet clear. In this study, cell-bubble behavior and cell damage were observed using a high-speed camera and a fluorescence microscope, and the mechanism of sonoporation was discussed. Based on observation results, we concluded that the cell membrane damage was mainly caused by mechanical stress induced by the bubble behavior. Cell viability was also studied under various conditions of ultrasound exposure, and it was shown that cell damage strongly depends on the presence of microbubbles and that cell damage increases with increase in pulse pressure.
  • HIRAI Kosuke, MAEGAWA Kazuya, KOHATA Daisuke, KUDO Nobuki, YAMAMOTO Katsuyuki  17-  341  -344  2002/09   [Not refereed] [Not invited]
  • OGIHARA Makoto, KUDO Nobuki, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  102-  (137)  13  -16  2002/06   [Not refereed] [Not invited]  
    Recently, there has been further progress of the performance of diagnostic ultrasound equipment due to improvement of focusing techniques of ultrasound. This means that ultrasound intensity increases at a focal point, and therefore adverse effect of ultrasound exposure has become a topic again among users of this equipment. In this study, we developed a system to accurately measure temperature rise caused by ultrasound exposure and discussed effects of blood perfusion on temperature rise in a soft tissue. To simulate blood perfusion of an in vivo soft tissue, we used an excised fresh liver that was perfused with saline using a circulation pump. Temperature rises were measured at a focal point of exposed ultrasound and a point at 5 mm far from the focus under various conditions of perfusion rate. In the measurements at perfusion rates of 0.30 and 0.68 l/min, temperature rises decreased by 25% and 55%, respectively, compared to those with no perfusion. From these results, we concluded that the effects of blood perfusion should be adequately taken in account in estimating a temperature rise in soft tissues.
  • Nakamura Kazuaki, Kitama Masataka, Misawa Kenji, Arisawa Junji, Shao Jun, Kudo Nobuki, Yamamoto Katsuyuki  Memoirs of the Hokkaido Institute of Technology  30-  261  -266  2002/03   [Not refereed] [Not invited]
  • KUDO Nobuki, KURIBAYASHI Kaori, NATORI Michiya, MORIYASU Fuminori, YAMAMOTO Katsuyuki  The Transactions of the Institute of Electronics, Information and Communication Engineers. A  84-  (12)  1492  -1499  2001/12   [Not refereed] [Not invited]
  • NAKAMURA Kazuaki, SHAO Jun, KUDO Nobuki, KITAMA Masataka, MISAWA Kenji, ARISAWA Junju, YAMAMOTO Katsuyuki  The Transactions of the Institute of Electronics, Information and Communication Engineers. A  84-  (12)  1525  -1532  2001/12   [Not refereed] [Not invited]
  • NAKAMURA Kazuaki, SHAO Jun, KUDO Nobuki, KITAMA Masataka, MISAWA Kenji, ARISAWA Junji, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  101-  (478)  87  -92  2001/11   [Not refereed] [Not invited]  
    Ultrasound-modulated light has recently been utilized to improve a spatial resolution of optical imaging of biological tissues. This paper describes a method for detecting the ultrasound-modulated light by using variations in speckle patterns. A pulsed laser beam was injected into a turbid medium and modulated by an ultrasound pulse. The pulsed loght was synchronized with the ultrasound, and a phase inversion technique was used so that a modulated component could be detected using a conventional CCD camera. To evaluate the usefulness of this technique, one-dimensional imaging of absorbing object embedded in a turbid medium was carried out in both of transmission and reflection methods. It was found that a modulated component can be extracted from scattered light by the proposed technique in both cases.
  • Hirai Kousuke, Niwayama Masatsugu, Kohata Daisuke, Maekawa Kazuya, Kudo Nobuki, Hamaoka Takafumi, Katsumura Toshihito, Yamamoto Katsuyuki  IEICE technical report. ME and bio cybernetics  101-  (130)  1  -8  2001/06   [Not refereed] [Not invited]  
    In recent years, continuous wave near-infrared spectroscopy (CW-NIRS) has been applied to in vivo reflectance imaging of muscle oxygenation. We previously developed a 200-channel imaging system that enables measurement of change in oxygenation and blood volume. However, we obtained the images of change in oxygenation and blood volume in an off-line mode after data processing. In this study, we have developed a real-time imaging system. Using the new system, we have imaged the change in oxygenation and blood volume in muscles of the whole thigh during various exercises at a rate of 5 frames/s. The results showed that difference in muscle function and fast changes in blood volume can be imaged and that this system is applicable to clinical medicine.
  • MIYAOKA Takehiro, FURUYA Junji, KUOD Nobuki, NIWA Kouichi, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  101-  (130)  83  -89  2001/06   [Not refereed] [Not invited]  
    Recently, it has been reported that activation of contrast agent gas bodies by ultrasound exposure can damage the cell membrane. To elucidate mechanisms of such cell damage, we improved an high-speed and high-magnification observation system using a new high-speed camera and an inverted microscope. microbubbles of 3 to several tens microns in diameter were exposed to 1 MHz or 250 kHz ultrasound, and their dynamic behaviors were observed in 24-frame sequential high-speed photographs at the maximum frame rate of 8 million frames per second. Typical movements of a bubble, such as rapid contraction resulting in destruction of the microbubble and non-uniform contraction accompanied with generation of a small stream, were observed. To study the possibility that these bubble movements can cause cell damage, bovine arterial endothelial cells and microbubbles were exposed to ultrasound. Non-uniform contraction of a microbubble and deformation of the cell beside the bubble were observed. It was suggested that a small stream generated by non-uniform contraction of a bubble could cause mechanical damage to a cell.
  • KUDO Nobuki, MIYAOKA Takehiro, OGIHARA Makoto, NATORI Michiya, YAMAMOTO Katsuyuki  28-  (3)  2001/04   [Not refereed] [Not invited]
  • Nakamura Kazuaki, Kitama Masataka, Misawa Kenji, Arisawa Junji, Sibayama Kaichiro, Shao Jun, Kudo Nobuki, Yamamoto Katsuyuki  Memoirs of the Hokkaido Institute of Technology  29-  217  -223  2001/03   [Not refereed] [Not invited]
  • KUDO Nobuki, ARITA Naoki, YAMAMOTO Katsuyuki  Symposium on ultrasonic electronics  (21)  347  -348  2000/11   [Not refereed] [Not invited]
  • Yamamoto Katsuyuki, Niwayama Masatsugu, Kudo Nobuki  IEICE technical report.  100-  (287)  19  -23  2000/09   [Not refereed] [Not invited]  
    In this talk, several new techniques for biomedical functional imaging using ultrasound and light will be presented. High-resolution imaging of tissues and blood flow in micro-vessels using a miniaturized ultrasound probe could be used for in vivo examination during biopsy and surgical operation. Vibration and rapture of micro-bubbles of ultrasound contrast agents can be observed by a ultra-high-speed camera, and results on dynamics of the bubbles give valuable, basic data for establishing highly efficient and safe contrast agents. Functional imaging of muscle oxygenation using near-infrared spectroscopy is one of the most useful techniques applicable to rehabilitation and sport medicine.
  • Kohata D., Niwayama M., Shao J., Kudo N., Hamaoka T., Katsumura T., Yamamoto K.  IEICE technical report. ME and bio cybernetics  100-  (163)  33  -38  2000/06   [Not refereed] [Not invited]  
    In recent years, continuous wave near-infrared spectroscopy(CW-NIRS)has been applied to in vivo reflectance imaging of muscle oxygenation. However, conventional mapping systems do not have a sufficient measurement area at present. In this study, we developed a 200-channel mapping system that enables measurement of change in oxygenation and blood volume and that covers a wider area(30cm×20cm)than do traditional systems. Using the new system, we obtained the images of change in oxygenation and blood volume in muscles of the whole thigh during two kinds of exercises. The results showed that difference in muscle function and tissue heterogeneity can be imaged.
  • Maegawa K., Niwayama M., Shao J., Kudo N., Yamamoto K.  IEICE technical report. ME and bio cybernetics  100-  (163)  39  -44  2000/06   [Not refereed] [Not invited]  
    Spatially resolved spectroscopy(SRS)is a method for measuring the optical properties of a medium using spatial profiles of reflectance. This method is useful for quantitative measurement of tissue oxygenation with continuous wave light in real time. However, conventional SRS theory is based on the assumption that tissue structure is homogeneous. This assumption can not be applied to actual inhomogeneous structures, and there might be great errors due to the inappropriate assumption. Therefore, we studied the influences of overlying tissues on muscle oxygenation measurement by 4-layer Monte Carlo simulations and proposed a correction method. There were great differences in in vivo measurements between conventional SRS and our correction method. This result suggested that correction is needed for quantitative measurement using SRS.
  • KUDO Nobuki, KURIBAYASHI Kaori, NATORI Michiya, MORIYASU Fuminori, YAMAMOTO Katsuyuki  27-  (4)  2000/04   [Not refereed] [Not invited]
  • KUDO Nobuki, KURIBAYASHI Kori, YAMAMOTO Katsuyki, NATORI Michiya, MORIYASU Fuminori  27-  (4)  2000/04   [Not refereed] [Not invited]
  • KUDO Nobuki, KURIBAYASHI Kaori, YAMAMOTO Katsuyuki, NATORI Michiya, MORIYASU Fuminori  2000-  (1)  1057  -1058  2000/03   [Not refereed] [Not invited]
  • IKEDA Takefumi, KUDO Nobuki, YAMAMOTO Katsuyuki  1999-  (21)  31  -35  1999/06   [Not refereed] [Not invited]
  • KUDO Nobuki, SHIBAYAMA Kaichiro, SHAO Jun, YAMAMOTO Katsuyuki  1999-  (21)  37  -42  1999/06   [Not refereed] [Not invited]
  • IKEDA Takefumi, KUDO Nobuki, YAMAMOTO Katsuyuki  26-  (4)  1999/04   [Not refereed] [Not invited]
  • KURIBAYASHI Kaori, KUDO Nobuki, NATORI Michiya, YAMAMOTO Katsuyuki  26-  (4)  1999/04   [Not refereed] [Not invited]
  • YOSHIDA Makoto, KUDO Nobuki, YAMAMOTO Katsuyuki, MIKAMI Taisei, KITABATAKE Akira  1998-  (5)  75  -80  1998/06   [Not refereed] [Not invited]
  • NIWAYAMA Masatsugu, SHIGA Toshikazu, LIN Ling, KUDO Nobuki, TAKAHASHI Makoto, YAMAMOTO Katsuyuki  1998-  (5)  81  -88  1998/06   [Not refereed] [Not invited]
  • YOSHIDA Makoto, KUDO Nobuki, YAMAMOTO Katsuyuki, MIKAMI Taisei, KITABATAKE Akira  IEICE technical report. ME and bio cybernetics  98-  (135)  75  -80  1998/06   [Not refereed] [Not invited]  
    In order to verify the contribution of a fibrous structure of biological tissue to ultrasound attenuation, we measured ultrasound attenuation coefficients of bovine muscular tissue in the frequency range of 10-40 MHz. Measurements were performed on a homogenized sample and a sliced sample, In the homogenized sample, supermatant of a muscular tissue suspension homogenized with a physiological saline was used. The sliced samples were cut in the normal and the parallel directions to a fibrous structure. An attenuation coefficient of homogenized sample increased proprtionally to the 1.5 power of frequency, while the attenuation coefficients of the sliced samples increased proportionally to the 1.9 power of frequency for the normal sample and the 1.2 power for the parallel sample, respectively. It is well known in a lower frequency than 10 MHz that ultrasound attenuation of fibrous tissue depends on a direction of the fibrous structure. Our results suggest that this angular dependence of the attenuation is caused by the change in the exponent value of frequency-dependent attenuation.
  • NIWAYAMA Masatsugu, SHIGA Toshikazu, LIN Ling, KUDO Nobuki, TAKAHASHI Makoto, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  98-  (135)  81  -88  1998/06   [Not refereed] [Not invited]  
    The inhomogeneity of tissue structure greatly affects the sensitivity of tissue oxygenation measurement by reflectance NIRS. We have proposed a method for correcting the influence of a subcutaneous fat layer on muscle oxygenation measurement. In this study, this method was validated by measuring the peak-to-peak variation of muscle oxygenation in periodic exercise tests on the vastus lateralis. A multisensor probe including a proximal detector was newly developed. A proximal detector was used to eliminate the effect of skin. Results of the tests clearly showed that the presence of a fat layer greatly decreases the sensitivity of measurement and increases the light intensity at the detectors. Sensitivity correction by detected light intensity resulted in almost the same changes in muscle oxygention among subjects regardless of different fat layer thicknesses. The proximal detector was also effective for reducing the effect of skin.
  • KUDO N., YOSHIDA M., YAMAMOTO K., MIKAMI T., KITABATAKE A., ITO Y., KANDA H.  25-  (4)  1998/04   [Not refereed] [Not invited]
  • KUDO Nobuki, ZHANG Xu, YAMAMOTO Katsuyuki  25-  (3)  1  -12  1998/03   [Not refereed] [Not invited]
  • ZHANG Xu, KUDOH Nobuyuki, YAMAMOTO Katsuyuki  J Med Ultrasonics  25-  (3)  13  -24  1998/03   [Not refereed] [Not invited]
  • NIWAYAMA Masatsugu, SHIGA Toshikazu, LIN Ling, KUDOU Nobuki, TAKAHASHI Makoto, YAMAMOTO Katsuyuki  Japanese journal of medical electronics and biological engineering  36-  (1)  41  -48  1998/03   [Not refereed] [Not invited]
  • KUDO N., YAMAMOTO K., ONOZUKA H., MIKAMI T., KITABATAKE A.  24-  (9)  1997/09   [Not refereed] [Not invited]
  • KUDO Nobuki, KANENARI Tetsuya, ZHANG Xu, YAMAMOTO Katsuyuki  24-  (9)  1997/09   [Not refereed] [Not invited]
  • KUDO N., YOSHIDA M., YAMAMOTO K., MIKAMI T., KITABATAKE A., ITO Y., KANDA H.  24-  (9)  1997/09   [Not refereed] [Not invited]
  • KANENARI Tetsuya, KUDO Nobuki, ZHANG Xu, TAKAHASHI Makoto, YAMAMOTO Katsuyuki  1997-  (16)  9  -16  1997/06   [Not refereed] [Not invited]
  • KANENARI Tetsuya, KUDO Nobuki, ZHANG Xu, TAKAHASHI Makoto, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  97-  (124)  9  -16  1997/06   [Not refereed] [Not invited]  
    Intravascular ultrasound (IVUS) imaging has recently been used widely in clinical examinations. Clear discrimination of vascular lumen using IVUS is important to quantify a degree of Vascular stenosis. But, in many cases, it is difficult to detect the boundary between lumen and a thrombosis because the difference of an acoustic impedance id small. In this paper, we propose a new IVUS method which enables us to discriminate the vessel lumen by detecting movement in regions of blood flow and a thrombosis. The Doppler technique can not detect this movement, because the blood flow is transverse to an ultrasound beam in a conventional IVUS system. We, therefore, used a newly developed correlation technique to detect the movement. Constructing an experimental system, we obtained correlation images of a vascular phantom. Experimental results showed that the blood flow was clearly discriminated from the thrombus, whereas the discrimination was difficult in conventional M-mode and B-mode images.
  • KUDO N., KAMATAKI T., YAMAMOTO K., ONOZUKA H., MIKAMI T., KITABATAKE A., ITO Y., KANDA H.  24-  (3)  1997/03   [Not refereed] [Not invited]
  • YAMAMOTO Katsuyuki, KUDO Nobuki  Journal of the Japan Society of Precision Engineering  62-  (11)  1541  -1544  1996/11   [Not refereed] [Not invited]
  • NIWAYAMA Masatsugu, SHIGA Toshikazu, LIN Ling, KUDO Nobuki, TAKAHASHI Makoto, YAMAMOTO Katsuyuki  IEICE technical report. ME and bio cybernetics  96-  (114)  51  -56  1996/06   [Not refereed] [Not invited]  
    Near-infrared spectroscopy (NIRS) has been found to be a useful technique for noninvasive monitoring of tissue oxygenation. Although the inhomogeneity of tissue structure may affect the sensitivity of the measurement, few analyses of this effect have been perfomed. In the present study, the influence of a subcutaneous fat layer on muscle oxygenation measurement using NIRS was examined by Monte Carlo simulation and experimental studies. From the results of the simulation, it was predicted that the sensitivity of the measurement greatly decreased with the increase of the fat layer thickness. In the experimental studies, the measurement sensitivity was examined by occlusion tests at the forearm and ergometer exercise at the vastus lateralis muscle, in which the fat thickness was measured by a diagnostic ultrasound equipment. The experimenrtal results also clearly showed the great decrease of the measurement sensitivity due to the presence of a fat layer.
  • Oyanagi M., Kudo N., Yanagida Y., Iwama N., Okazaki K.  Symposium on ultrasonic electronics  (14)  165  -166  1993/12   [Not refereed] [Not invited]

Awards & Honors

  • 2005   Best Presentation Award
       japan

Research Grants & Projects

  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(A))
    Date (from‐to) : 2008 -2010 
    Author : Nobuki KUDO
     
    北海道大学The final goal of this study was to develop a safe and efficient method for in vivo sonoporation that uses short-pulsed ultrasound in the presence of microbubbles adjacent to cells. A light microscopy system was developed for time-lapse observation of changes in cells generated during sonoporation and used to study methods to improve efficiency of the sonoporation. Optical tweezers were included in the system to control the position and extent of membrane damage by changing bubble size and position. Cell membrane damage and repair, which occur in a period shorter than 20 minutes, were obser...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2007 -2008 
    Author : Yamamoto KATSUYUKI
     
    北海道大学
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2004 -2006 
    Author : Katsuyuki YAMAMOTO
     
    北海道大学In this study, a small and lightweight instrument based on spatially resolved near-infrared spectroscopy (SR-NIRS) was developed for real-time imaging of muscle oxygenation. From the results of temporal and spatial analyses of muscle oxygenation during exercise tests, we elucidated the relationship between changes in muscle oxygenation and metabolism and established the basics of NIRS as a standard technique for functional imaging of muscle. The following results were obtained.1. Development of an imaging instrument for muscle oxygenation based on spatially resolved NIRSCompact multi-channe...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2004 -2006 
    Author : Nobuki KUDO
     
    北海道大学Improvement of a high-speed observation systemTo improve spatial and temporal resolutions of high-speed observation, the use of an image intensifier with a high-speed camera and the use of an improved optical condenser for a short-arc flash lamp were examined. The use of these devices resulted in a reduction in minimum exposure time from 200 ns to 20 ns at a 40x objective and an increase in maximum framing rate from 4-million to 16-million fps.Development of a system for measurement of pressure-dependent attenuationA system for measurement of attenuation of microbubble suspensions was devel...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2001 -2003 
    Author : Katsuyuki YAMAMOTO
     
    北海道大学The purpose of this research project was to experimentally verify the causal relationships between measurements of near-infrared spectroscopy and the mechanisms of oxygen transport to the skeletal muscles. These relationships are essential for understanding temporal responses of NIRS measurements. The following results were obtained from measurements in volunteers, computer simulation of tissue metabolism and microspectroscopic studies in animals.(1) Spatio-temporal analyses of muscle metabolism based on muscle oxygenation imaging : An imaging system of muscle oxygen saturation using spatia...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2001 -2002 
    Author : Nobuki KUDO
     
    北海道大学To improve spatial resolution of optical imaging of biological tissue, a new method using speckle patterns of ultrasound-modulated light was proposed. Results of experimental evaluations of the proposed method are summarized as follows.1. A proposed method and an experimental system : To detect temporal variations of optical speckle patterns in ultrasound frequency, we used a conventional CCD still camera and introduced a principle of a strobe scope, that is, the shutter of the CCD still camera is open and the object observed is illuminated by pulsed light synchronized with exposed ultrasou...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 1999 -2001 
    Author : Katsuyuki YAMAMOTO
     
    北海道大学The objectives of this study were to develop a tissue oxygen monitor that can eliminate the influence of a fat layer on muscle oxygenation measurement using near-infrared spectroscopy (NIRS) and to establish quantitative NIRS by verifying the validity of this technique in the field of sports medicine.1. Mean optical properties (absorption and scattering coefficients) of muscle and adipose tissues were determined by comparing results of in vivo measurements using time-resolved NIRS with those of Monte Carlo simulation using a multi-layered model.2. A nonlinear algorithm for tissue oxygenatio...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 1998 -2000 
    Author : Makoto TAKAHASHI
     
    北海道大学A number of children with learning disabilities (LD) are not good at visuomotor control. In this study, we analyzed hand trajectories of reaching movements under rotated visual feedback in subjects with and without LD.Each reaching movement has two components : an "initial impulse" (ballistic movement) and a series of "secondary adjustments" (corrective movement) made subsequently to attain the final target position. In the present study, the error in ballistic movement was determined by measuring the angle between the direction in which the subject started to reach out and the direction of...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 1998 -2000 
    Author : Katsuyuki YAMAMOTO
     
    北海道大学In this study, a new technique to improve a spatial resolution of optical imaging of biological tissues using ultrasound-modulated light was developed, and the following results were obtained.Study on mechanisms of light modulation by ultrasoundTwo high-sensitivity detection systems of ultrasound-modulated light using a photomultiplier or an interferometer were developed. Relationships between a signal intensity of ultrasound-modulated light and a scattering coefficient of a turbid medium were obtained from experiments on a tissue phantom. Based on these relationships, the mechanisms of lig...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 1998 -2000 
    Author : Nobuki KUDO
     
    北海道大学In this study, a high-frequency miniaturized ultrasound probe mounted on a puncturing needle and an imaging system for this probe have been developed. The usefulness of this imaging system has been evaluated in in vitro and in vivo experiments. We have also studied the feasibility of tissue characterization using ultrasound attenuation in a high-frequency region. The following results were obtained.Development of the miniaturized ultrasound probe and imaging system A miniaturized probe mounted on a 16-20 gage puncturing needle that can be stuck into a tissue has been developed. A 2-D ultras...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 1996 -1998 
    Author : Makoto TAKAHASHI
     
    北海道大学The research objective is the construction process of the human inner space when several kinds of audio-visual stimulation are applied. When stimulating time is varied, accuracy of location of stimulation and posture movement were measured. Two types of experimentes have been performed. One is sitting experiment and the other is standing one. Sitting at the center of the semicircle (1.5 m radius) with arrangement of red LEDs and speakers of which interval is 10 degrees., subject indicates the direction of stimulus in a dark and silent room. Motion of the head and the indicating direction ar...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(A))
    Date (from‐to) : 1996 -1998 
    Author : Katsuyuki YAMAMOTO
     
    北海道大学A portable tissue oximeter based on two-wavelength near-infrared spectroscopy with multiple photo sensors was developed for a real-time, ambulatory measurement of muscle oxygenation. This oximeter can eliminate the influences of inhomogeneous structure of tissues on the measurement and is useful for quantitative evaluation of muscle oxygenation in the fields of sports and rehabilitation medicine as well as in muscle tissue physiology. Important results of this study are summarized as follows.Development of the portable tissue oximeter : The oximeter was made compact for the ambulatory measu...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 1996 -1997 
    Author : Katsuyuki YAMAMOTO
     
    北海道大学The purpose of this study is to clarify the causal relationship between mechanical stress and alveolar bone remodeling during orthodontic treatment. Material constants of the periodontal ligament (PDL) are indispensable parameters for stress analysis of a tooth and the surrounding tissues. However, few experimentally determined values have been reported. In this study, we developed a small compressive and tensile test machine in order to determine the material constants of the PDL.In tension tests, stress-strain curves did not significantly depend on strain rates. In contrast, compressive t...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 1996 -1997 
    Author : Koichi SHIMIZU
     
    北海道大学A fundamental study was conduced to realize the transilumination and the CT imaging of biological functions using multi-wavelength and ultra-short light pulse. Through this research the following progresses were made.(1) Through theoretical and experimental study, it was shown that we can get the image of functional change occurred inside an animal body using the light of multiple wavelengths in near-infrared region. The imaging can be perfomed noninvasively with a relatively simple apparatus.(2) A transilumination imaging system was developed based on the proposed principle. Using this sys...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 1996 -1997 
    Author : Nobuki KUDO
     
    北海道大学1.RF echo processingWe developed a new time domain correlation technique for detecting displacement and velocity vectors. The technique is based on calculation of the correlation between RF echo detected by a single transducer at a fixed repetition rate. Relation between the velocity vector and correlation was derived theoretically. Advanced RF signal processing techniques for evaluation of structure and charactor of biological tissue were also discussed.2.Measurement system>>Transducers for IVUSSmall transducers (1.2mm * 0.8mm) which can be used in the IVUS catheter were developed. Improve...
  • Measurements of biomedical parameters using optical and ultrasonic techniques
    Date (from‐to) : 1995

Educational Activities

Teaching Experience

  • 人間機能情報学特論
    開講年度 : 2017
    課程区分 : 博士後期課程
    開講学部 : 情報科学研究科
  • Bioengineering
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 情報科学研究科
    キーワード : 遺伝情報, genetic information, バイオインフォマティクス, bioinformatics, イメージング, imaging, 生体医工学, biomedical engineering, 細胞力学, cell mechanics
  • バイオメカニクス特論
    開講年度 : 2017
    課程区分 : 博士後期課程
    開講学部 : 情報科学研究科
  • Medical Systems Engineering
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 情報科学研究科
    キーワード : 医用システム,医用計測,医用画像,診断・治療機器,医用情報,医用安全,生体医工学.
  • Bioengineering
    開講年度 : 2017
    課程区分 : 博士後期課程
    開講学部 : 情報科学研究科
    キーワード : 遺伝情報, genetic information, バイオインフォマティクス, bioinformatics, イメージング, imaging, 生体医工学, biomedical engineering, 細胞力学, cell mechanics
  • Medical Systems Engineering
    開講年度 : 2017
    課程区分 : 博士後期課程
    開講学部 : 情報科学研究科
    キーワード : 医用システム,医用計測,医用画像,診断・治療機器,医用情報,医用安全,生体医工学.
  • Applied Electric Circuits
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 非周期波,周波数応答,過渡応答,分定数回路
  • Scientific Measurements and Instrumentation
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 電気計測,電子計測,波形分析,センサ,応用計測


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