Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Sera Toshihiro Last modified date:2021.06.08

Associate Professor / Biomechanical Engineering / Department of Mechanical Engineering / Faculty of Engineering


Papers
1. Toshihiro Sera, Naoki Kamiya, Taichi Fukushima, Gaku Tanaka, Visualizing the flow patterns in an expanding and contracting pulmonary alveolated duct based on micro-computed tomography images, Journal of Biomechanical Engineering, https://doi.org/10.1115/1.4050285, 143, 7, 2021.07.
2. Shinya Kimura, Takashi Sakamoto, Toshihiro Sera, Hideo Yokota, Kenji Ono, Denis J. Doorly, Robert C, Voxel-based simulation of flow and temperature in the human nasal cavity, Computer Methods in Biomechanics and Biomedical Engineering, https://doi.org/10.1080/10255842.2020.1836166, 2020.10.
3. Toshihiro Sera; Taiki Kohno; Yusuke Nakashima; Musashi Uesugi, Low frequency oscillations of finger skin blood flow during the initial stage of cold-induced vasodilation at different air temperatures, Journal of Physiological Anthropology, https://doi.org/10.1186/s40101-020-00248-4, 39, Article number: 37, 2020.11.
4. Toshihiro Sera, Shiro Higa, Yan Zeshu, Kyosuke Takahi, Satoshi Miyamoto, Tetsuya Fujiwara, Hideo Yokota, Saori Sasaki, Susumu Kudo, A metabolic reaction–diffusion model for PKCα translocation via PIP2 hydrolysis in an endothelial cell, Biochemical Journal, Biochemical Journal, 447, 20, 4071-4084, 2020.09.
5. Toshihiro Sera, Susumu Kudo, Mathematical models for intra- and inter-cellular Ca2+ wave propagations, Journal of Biorheology, 34, 1, 9-17, 2020.06.
6. Toshihiro Sera, Marie Terada, Susumu Kudo, Heterogeneous reorganization of actin filaments in living endothelial cells in response to shear stress, Journal of Biorheology, 34, 1, 18-24, 2020.06.
7. Masakazu Umezawa, Toshihiro Sera, Hideo Yokota, Maho Takematsu, Masahiko Morita, Gil Yeroslavsky, Masao Kamimura, Kohei Soga, Computed Tomography for In Vivo Deep Over-1000 nm Near-Infrared Fluorescence Imaging, Journal of Biophotonics, 2020.05.
8. Toshihiro Sera, Hiroaki Kuninaga, Kazuaki Fukasaku, Hideo Yokota, Masao Tanaka, The effectiveness of an averaged airway model in predicting the airflow and particle transport through the airway, Journal of Aerosol Medicine and Pulmonary Drug Delivery, 32, 5, 278-292, 2019.10.
9. Kenichiro Koshiyama, Keisuke Nishimoto, Satoshi Ii, Toshihiro Sera, and Shigeo Wada,, Heterogeneous structure and surface tension effects on mechanical response in pulmonary acinus: A finite element analysis, Clinical Biomechanics, https://doi.org/10.1016/j.clinbiomech.2018.01.001, 66, 32-39, 2019.06.
10. Toshihiro Sera, Masataka Arai, Zhunghua Cui, Koichi Onose, Alireza Karimi, Susumu Kudo, Unloading of intercellular tension induces the directional translocation of PKCα, Journal of Cellular Physiology, 234, 9764-9777, 2019.06.
11. Toshihiro Sera, Hiroaki Kobayashi, Masato Hoshino, Kentaro Uesugi, Takeshi Matsumoto, Masao Tanaka, The disuse effect on canal network structure and oxygen supply in the cortical bones of rats, Biomechanics and Modeling in Mechanobiology, 18, 2, 375-385, 2019.04.
12. Alireza Karimi, Reza Razaghi, Toshihiro Sera, and Susumu Kudo, A combination of the finite element analysis and experimental indentation via the cornea, Journal of the Mechanical Behavior of Biomedical Materials, 90, 146-154, 2019.02.
13. Shinya Kimura, Takashi Sakamoto, Toshihiro Sera, Hideo Yokota, Kenji Ono, Denis J. Doorly, Robert C. Schroter, Gaku Tanaka, Voxel-based modeling of airflow in the human nasal cavity, Computer Methods in Biomechanics and Biomedical Engineering, 22, 3, 331-339, 2019.02.
14. Alireza Karimi, Reza Razaghi, Seyed Mohammadali Rahmati, Toshihiro Sera, and Susumu Kudo, A nonlinear dynamic finite element analyses of the basketball-related eye injuries, Sports Engineering, 21, 4, 359-365, 2018.12.
15. Toshihiro Sera, Shingo Komine, Masataka Arai, Yasuhiro Sunaga, Hideo Yokota, Susumu Kudo, Three-dimensional model of intracellular and intercellular Ca2+ waves propagation in endothelial cells, Biochemical and Biophysical Research Communications, 505, 3, 781-786, 2018.11.
16. Yumi Takiyama, Toshihiro Sera, Masanori Nakamaura, Kanaki Ishizeki, Yasuaki Saijo, Tsuyoshi Yanagimachi, Manami Maeda, Ryoichi Bessho, Takao Takiyama, Hiroya Kitsunai, Hidemitsu Sakagami, Daisuke Fujishiro, Yukihiro Fujita, Yuichi Makino, Atsuko Abiko, Masato Hoshino, Kentaro Uesugi, Naoto Yagi, Tsuguhito Ota, Masakazu Haneda, Impact of Diabetes and an SGLT2 Inhibitor on Glomerular Number and Volume in db/db Mice as Estimated by Synchrotron Radiation Micro-CT at SPring-8, EBioMedicine, 2018.10.
17. Toshihiro Sera, Masataka Arai, Takumi Hasegawa, Susumu Kudo,, A mechanically wounding induces biphasic and directional translocation of protein kinase Cα before cell migration, Proceeding of 8th World Congress of Biomechanics, 2018.09.
18. Toshihiro Sera, Shingo Komine, Masataka Arai, Yasuhiro Sunaga, Hideo Yokota, Susumu Kudo, , Evaluation of intracellular and intercellular Ca2+ wave propagation in endothelial cells using by numerical and experimental approaches, Proceeding of 8th World Congress of Biomechanics, 2018.09.
19. Alireza Karimi, Reza Razaghi, Hasan Biglari, Toshihiro Sera, and Susumu Kudo, Collision of the glass shards with the eye: A computational fluid-structure interaction model, Journal of Chemical Neuroanatomy, 90, 80-86, 2018.07.
20. Masataka Arai, Toshihiro Sera, Takumi Hasegawa, Susumu Kudo, Spatial and temporal translocation of PKCα in single endothelial cell in response to mechanical stimulus, Experimental Cell Research, 367, 2, 205-215, 2018.06.
21. Alireza Karimi, Reza Razaghi, Hamideh Sabbaghi, Toshihiro Sera, and Susumu Kudo, A comparative study to determine the optimal intravitreal injection angle to the eye: A computational fluid-structure interaction model, Technology and Health Care, 10.3233/THC-160777, 2018.05.
22. Toshihiro Sera, Tateki Sumii, Ryosuke Fujita, Susumu Kudo, Effect of shear stress on the migration of hepatic stellate cells, In Vitro Cellular & Developmental Biology - Animal, 54, 11-12, 2018.01.
23. Alireza Karimi, Toshihiro Sera, Susumu kudo, Mahdi Navidbakhsh, Experimental verification of the healthy and atherosclerotic coronary arteries incompressibility via digital image correlation, Artery Research, https://doi.org/10.1016/j.artres.2016.08.002, 16, 1-7, 2017.12.
24. Masataka Arai, Tomoya Shimada, Chihiro Kora, Kazuhiro Nakashima, Toshihiro Sera, and Susumu Kudo, Biphasic and directed translocation of protein kinase Cα inside cultured endothelial cells before migration, Biochemistry and Biophysics Reports, 12, 91-97, 2017.12.
25. Alireza Karimi, Reza Razaghi, Toshihiro Sera, and Susumu Kudo, Mechanical properties of the human sclera under various strain rates: Elastic, hyperelastic, and viscoelastic models, Journal of Biomaterials and Tissue Engineering, 7, 686-695, 2017.08.
26. Toshihiro Sera, Yuya Iwai, Takaharu Yamazaki, Tetsuya Tomita, Hideki Yoshikawa, Hisahi Naito, Takeshi Matsumoto, Masao Tanaka, Strain measurements of the tibial insert of a knee prosthesis using a knee motion simulator, Journal of Orthopaedics, 14, 4, 495-500, 2017.08.
27. Toshihiro Sera, Ryosuke Higashi, Hisashi Naito, Takeshi Matsumoto, Masao Tanaka, Distribution of nanoparticle depositions after a single breathing in a murine pulmonary acinus model, International Journal of Heat and Mass Transfer, 108, 730-739, 2017.05.
28. Alireza Karimi, Reza Razaghi, Mahd Navidbakhsh, Toshihiro Sera, Susumu Kudo, Computing the influences of different Intraocular Pressures on the human eye components using computational fluid-structure interaction model, TECHNOLOGY AND HEALTH CARE, 10.3233/THC-161280, 25, 2, 285-297, 2017.03.
29. Alireza Karimi, Seyed Mohammadali Rahmati, Toshihiro Sera, Susumu kudo, Mahdi Navidbakhsh, A combination of constitutive damage model and Artificial Neural Networks to characterize the mechanical properties of the healthy and atherosclerotic human coronary arteries, Artificial Organs, 10.1111/aor.12855., 41, 9, E103-E117, 2017.02.
30. Luosha Xiao, Toshihiro Sera, Kenichiro Koshiyama, Shigeo Wada, Morphological Characterization of Acinar Cluster in Mouse Lung Using a Multiscale-based Segmentation Algorithm on Synchrotron Micro-CT Images, The Anatomical Record, 10.1002/ar.23452, 299, 10, 1424-1434, 2016.10.
31. T. Shinohara, T. Kai, K. Oikawa, M. Segawa, M. Harada, T. Nakatani, M. Ooi, K. Aizawa, H. Sato, T. Kamiyama, H. Yokota, Toshihiro Sera, K. Mochiki, Y. Kiyanagi, Final design of the Energy-Resolved Neutron Imaging System “RADEN” at J-PARC, Journal of Physics: Conference Series, doi:10.1088/1742-6596/746/1/012007, 746, 1, 2016.09.
32. Shun Shimizu, Takashi Sakamoto, Shinya Kimura, Gaku Tanaka, Toshihiro Sera, Hideo Yokota, Kenji Ono, Effect of Inflow Boundary Condition on Nasal Transitional Flow, Proceedings of Summer Biomechanics, Bioengineering, and Biotransport Conference, 2016.07.
33. Yuri Inagaki, Keisuke Yamanaka, Gaku Tanaka, Toshihiro Sera, Simulation of Airflow in Realistic Model Pulmonary Acinus, Proceedings of Summer Biomechanics, Bioengineering, and Biotransport Conference, 2016.07.
34. Toshihiro Sera, Hiroaki Kuninaga, Kazuaki Fukasaku, Hideo Yokota, Masao Tanaka, , Influence of Standardization of Airway Geometry on Airflow and Particle Transport, Proceedings of Summer Biomechanics, Bioengineering, and Biotransport Conference, 2016.07.
35. Alireza Karimi, Seyed Mohammadali Rahmati, Toshihiro Sera, Susumu kudo, Mahdi Navidbakhsh, A Combination of Experimental and Numerical Methods to Investigate the Role of Strain Rate on the Mechanical Properties and Collagen Fiber Orientations of the Healthy and Atherosclerotic Human Coronary Arteries, Bioengineered, 10.1080/21655979.2016.1212134, 2016.02.
36. Ryosuke Higashi, Toshihiro Sera, Hisashi Naito, Takeshi Matsumoto, Masao Tanaka, Pulmonary kinematic analysis with non-rigid deformable registration for detecting localized emphysema, Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 10.1080/21681163.2015.1008649, 2015.04.
37. H.Sakai, Y.Watanabe, Sera Toshihiro, Yokota Hideo, Tanaka Gaku, Visualization of particle deposition in human nasal cavities, Journal of Visualization, 18, 2, 349-357, 2014.10.
38. Sera Toshihiro, Kentaro Uesugi, Naoto Yagi, Hideo Yokota, Numerical simulation of airflow and microparticle deposition in a synchrotron micro-CT based pulmonary acinus model, Computer Methods in Biomechanics and Biomedical Engineering, 13, 1-9, 2014.05.
39. Luosha Xiao, Toshihiro Sera, Kenichiro Koshiyama, and Shigeo Wada, , Morphological analysis of mouse pulmonary acini extracted from synchrotron micro-CT images with a multiscale-based segmentation algorithm, Proceedings of 15th International Conference on Biomedical Engineering, 2013.12.
40. Toshihiro SERA, Hideo Yokota, Ryutaro Himeno, Gaku Tanaka, Gas dispersion of oscillatory flow in expanding and contracting multi-branching airways, International Journal of Heat and Mass Transfer, 65, 627-634, 2013.10.
41. Masato Hoshino, Kentaro Uesugi, Toshihiro Sera, Nato Yagi, X-ray micro-tomography using white beam radiation from SPring-8, Journal of Instrumentation, 2013.07.
42. Sera Toshihiro, Hideo Yokota, Gaku Tanaka, Kentaro Uesugi, Naoto Yagi, Robert C Schroter, Murine pulmonary acinar mechanics during quasi-static inflation using synchrotron refraction-enhanced computed tomography, JOURNAL OF APPLIED PHYSIOLOGY, 10.1152/japplphysiol.01105.2012, 115, 2, 219-228, 2013.07.
43. Shigeo Wada, Kenichiro Koshiyama, Luosha Xiao, Toshihiro Sera, Modeling and Measurements of Pulmonary Microstructure Toward Multiscale Analysis of the Lung Mechanics, Proceedings of 35th Annual International IEEE EMBS Conference, 2013.07.
44. Masato Hoshino, Toshihiro Sera, Kentaro Uesugi, Nato Yagi, Development of X-ray triscopic imaging system towards three-dimensional measurements of dynamical samples, Journal of Instrumentation, 2013.05.
45. Luosha Xiao, Toshihiro Sera, Kenichiro Koshiyama, Shigeo Wada, A Semiautomatic Segmentation Algorithm for Extracting the Complete Structure of Acini from Synchrotron Micro-CT Images, COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE, 10.1155/2013/575086, 2013.03.
46. Sera Toshihiro, Hideo Yokota, Kentaro Uesugi, Naoto Yagi, Airway distension during lung inflation in healthy and allergic-sensitised mice in vivo, RESPIRATORY PHYSIOLOGY & NEUROBIOLOGY, 10.1016/j.resp.2012.12.002, 185, 3, 639-646, 2013.02.
47. Gaku Tanaka, Kazuki Ohta, Fuyuto Araki, Toshihiro Sera, Hideo Yokota, Kdenji Ono, Shu Takagi,, Voxel-based simulation of air-conditioning in the human nasal cavity, Proceedings of the 3rd International Forum on Heat Transfer, 2012.11.
48. Takeshi Nishizawa, Yuya Watanabe, Yoshihiro Takimoto, Gaku Tanaka, Toshihiro Sera, Hideo Yokota, Visualization and Measurement of airflow in the human nasal cavities, Proceedings of the 8th KSME-JSME Thermal and fluids engineering conference, 2012.04.
49. Gaku Tanaka, Shinya Kimura, Toshihiro Sera, Nobunori Kakusho, Hideo Yokota, Kenji Ono, Shu. Takagi, , Voxel-based simulation of airflow in the human nasal cavities, Proceedings of the 8th KSME-JSME Thermal and fluids engineering conference, 2012.04.
50. Gaku Tanaka, Masayoshi Ohgawara, Genri Inagaki, Makoto Hishida, Toshihiro Sera, Kinematic irreversibility of oscillatory flow in expanding and contracting small airways, International Journal of Heat and Mass Transfer, 10.1016/j.ijheatmasstransfer.2011.11.040, 55, 7-8, 1873-1880, 2012.03, Computational fluid dynamics (CFD) simulation was carried out for an oscillatory flow in an expanding and contracting model of small airways, and the effects of airway geometry and rhythmic breathing motion on the kinematic irreversibility of oscillatory flow were revealed. A 3D realistic model of multi-branching small airways was reconstructed from X-ray CT images of a mouse, which were obtained by the high-resolution synchrotron radiation CT system of SPring-8. Airway diameters range from 360 μm in the primary branch to 55 μm in the distal branch. The airway model was expanded and contracted in a sinusoidal volume change with time such that the geometry remains self-similar throughout a period. The Fluent software package was used for calculation of the fluid particle trajectory in the airway model. The dispersion of the fluid particle was evaluated in terms of the variance of the marked minute particles in the axial direction. The results show that the axial dispersion is enhanced by the expanding and contracting motion of the airways. It was also found that the augmentation of steady streaming is responsible for enhanced dispersion of fluid particles..
51. Toshihiro Sera, Hideo Yokota, Sakiko Nakamura, Kentaro Uesugi, Masato Hoshino, Naoto Yagi, Toshio Ito, Keigo Hikishima, Hirotaka J. Okano, Synchrotron refraction enhanced tomography of an intact common marmoset (Callithrix jacchus), Open Journal of Radiology, 1, 28-37, 2011.12.
52. Essam A Rashed, Hiroyuki Toda, Toshihiro Sera, Akira Tsuchiyama, Tsukasa Nakano, Kentaro Uesugi, Hiroyuki Kudo, , Towards a high-resolution local tomography using statistical iterative reconstruction, Proceeding of IEEE Nuclear Science Symposium Conference, 2011.10.
53. Takuya Sakata, Gaku Tanaka, Toshihiro Sera, Nobunori Kakusho, Hideo Yokota, Kenji Ono and Shu Takagi, , Voxel-based modeling of airflow in the nasal cavities, Proceeding of 9th International Symposium of Computer Methods in Biomechanics and Biomedical Engineering, 2010.08.
54. Shinya Morita, Yutaka Yamagata, Katsuya Hirota, Shunsuke Mihara, Dinh T. Dung, Hideyuki Sunaga, Toshihiro Sera, Hideo Yokota, Takenao Shinohara, Naoto Metoki, and Akitake Makinouchi,, Neutron radiography for the structural simulation using VCAD system, Proceedings of the 19th Meeting of the International Collaboration on Advanced Neutron Sources, 2010.03.
55. T. Sera, K. Uesugi, N. Yagi, K. Umetani, M. Kobatake, S. Imai, High-resolution visualization of tumours in rabbit lung using refraction contrast X-ray imaging, European Journal of Radiology, 10.1016/j.ejrad.2008.04.030, 68, 3 SUPPL., S54-S57, 2008.12, Contrast enhancement by refraction was used to visualize tumours in the rabbit lung. VX2 tumour cells were intravenously injected into a rabbit. After 14 days the rabbit was euthanized and the lungs were imaged. Refraction-enhanced X-ray images were obtained with a sample-to-detector distance of 2.65-6 m. The beamline BL20B2 at the SPring-8 synchrotron radiation facility was used for the experiment, with a monochromatic X-ray beam with an energy of 33.2 keV. In the case of projection images, it was found that refraction did not help visualization of small tumours: the nodules did not show up with sharply defined edges. In tomography, tumours with a size of 1-10 mm were clearly visualized, together with blood vessels with a diameter down to 0.4 mm. These results show that refraction-enhanced imaging may be useful in human lung tomography to find small tumours..
56. Toshihiro Sera, Hideo Yokota, Kazuhiro Fujisaki, Kazuaki Fukasaku, Hiroyuki Tachibana, Kentaro Uesugi, Naoto Yagi, Ryutaro Himeno, Development of high-resolution 4D in vivo-CT for visualization of cardiac and respiratory deformations of small animals, Physics in Medicine and Biology, 10.1088/0031-9155/53/16/005, 53, 16, 4285-4301, 2008.08, The interest in small animal models of human diseases has generated a need to design a computed tomography (CT) system that operates at a microscopic level. It is particularly important to be able to visualize the dramatic rhythmical motion of organs such as the heart and lungs. In order to evaluate the motion of the heart and lungs of small animals (rats and mice), we developed in the present study a high-resolution 4D in vivo-CT system for small animals that uses synchrotron radiation. To reduce motion artifacts and the radiation dose, the projections were synchronized with airway pressure, the ECG, the x-ray shutter and the CCD shutter. For cardiovascular imaging, a blood pool contrast agent was injected and the data sets were acquired at several ECG points during the end-expiratory phase. For imaging of the lungs, the data sets were acquired at several airway pressures during diastole. The dynamic motion of the cardiovascular system (the ventricles and coronary arteries) and small airways (diameter > 250 μm of rats and 125 μm of mice) was visualized. This high-resolution imaging tool may be very useful for the development of novel drugs in murine models, in addition to its use in the study of cardiovascular and respiratory physiology..
57. Toshihiro Sera, Hideo Yokota, Kazuhiro Fujisaki, Kazuaki Fukasaku, Kentaro Uesugi, Naoto Yagi, Ryutaro Himeno, , Development of 4-d high-resolution CT for measurement of airway deformation, Proceedings of 2007 ASME Bioengineering Conference, 2007.07.
58. Toshihiro Sera, Kentaro Uesugi, Ryutaro Himeno, Naoto Yagi, Small airway changes in healthy and ovalbumin-treated mice during quasi-static lung inflation, Respiratory Physiology and Neurobiology, 10.1016/j.resp.2006.11.006, 156, 3, 304-311, 2007.06, Previously, we developed a synchrotron radiation CT system to evaluate the morphometric changes (length and diameter, D) and small airway compliance (sCaw) of euthanized mice under quasi-static inflation [Sera, T., Uesugi, K., Yagi, N., 2005. Localized morphometric deformations of small airways and alveoli in intact mouse lungs under quasi-static inflation. Respir. Physiol. Neurobiol. 147, 51-63). Using this system, this study compared normal and asthmatic small airways. Ovalbumin-treated mice were used as an asthma model. Compared with the values at functional residual capacity, D of normal and asthmatic small airways (D < 200 μm) increased by 48% and 36% at the end of tidal inspiration. For larger airways (D > 500 μm), the increases were 23% and 20%, respectively. The ratio of the sCaw of asthmatic small airways to that of healthy small airways was 0.57, and the ratio was 0.70 for larger airways. The morphometric changes and sCaw in asthma model mice were significantly lower than those of healthy mice. The differences in sCaw between healthy and asthma model mice were greater for smaller airways..
59. Toshihiro Sera, Hideo Yokota, Kazuhiro Fujisaki, Kazuaki Fukasaku, Kentaro Uesugi, Naoto Yagi, Ryutaro Himeno,, In vivo-CT system with respiratory and cardiac gating using synchrotron radiation, Conference proceeding of SPIE Medical Imaging, 6512, 2007.02.
60. Kentaro Uesugi, Toshihiro Sera, Naoto Yagi, Fast tomography using quasi-monochromatic undulator radiation, Journal of Synchrotron Radiation, 10.1107/S0909049506023466, 13, 5, 403-407, 2006.09, A beamline with a helical undulator has been used without a monochromator for fast high-resolution tomographic imaging with an X-ray energy of 12.4-16.5 keVand an energy bandwidth of 2-3%. The X-ray beam was expanded with two mirrors to 12 mm × 4 mm. The X-ray field was made uniform by a diffuser. The detector pixel size was 9.9 μm × 9.9 μm. At the highest speed, a 180° scan was completed in 6 s with 454 projections. Beam-hardening effects were not significant. This technique may be useful in studying time-dependent structural changes of soft materials such as polymers and biological samples..
61. Toshihiro Sera, Kentaro Uesugi, Naoto Yagi, , Small Airway Compliance of Healthy and Asthmatic Mice Measured by Synchrotron Radiation CT, Proceedings of 12th International Conference on Biomedical Engineering, 2005.12.
62. T. Sera, K. Uesugi, N. Yagi, Refraction-enhanced tomography of mouse and rabbit lungs, Medical physics, 10.1118/1.2008429, 32, 9, 2787-2792, 2005.09, In order to evaluate the effectiveness of edge enhancement by refraction in computed tomography, images of a cross section of a euthanized mouse thorax were recorded at low (20 keV) and high (72 keV) x-ray energies at a spatial resolution of about 40 μm. Compared with the images obtained with the detector at 30 cm from an object, when the object was located at 113 cm from the detector, the contrast between tissues and air was improved at both energies. The improvement was more pronounced at 72 keV where the absorption contrast was weaker. This effect was due to refraction at the surfaces of alveolar membranes and small airways which creates areas with apparently high and low linear attenuation coefficients within tissues. The edge enhancement by refraction was also effective in images of a euthanized rabbit thorax, at x-ray energies of 40 and 70 keV at a spatial resolution of about 0.15 mm. These results raise the possibility that the refraction contrast may be utilized to obtain a high-resolution tomographic image of human lung and bone with low dose..
63. Toshihiro Sera, Kentaro Uesugi, Naoto Yagi, Morphometric deformations of small airways and alveoli under quasi-static inflation process, Journal of physiological anthropology and applied human science, 10.2114/jpa.24.465, 24, 4, 465-468, 2005.07, Localized morphometric deformations of small airways and alveoli during respiration have many biomedical and physiological implications. We developed fast synchrotron radiation CT system to visualize the small airways and alveoli of an intact mouse lung without fixation and dehydration, and analyzed their localized morphometric deformations between functional residual capacity (FRC) and total lung capacity (TLC). In the diameter behavior, the averaged and range values were significantly larger for smaller airways (68.8%, range: 0.36-0.89) than larger airways (45.2%, range: 0.40-0.57). These results indicated that the airway did not deformed in same manner and that these morphological differences characterized the heterogeneous lung function..
64. Toshihiro Sera, Kentaro Uesugi, Naoto Yagi, Localized morphometric deformations of small airways and alveoli in intact mouse lungs under quasi-static inflation, Respiratory Physiology and Neurobiology, 10.1016/j.resp.2005.02.003, 147, 1, 51-63, 2005.05, Localized morphometric deformations of small airways and alveoli during respiration have several biomechanical and physiological implications. We developed fast synchrotron radiation CT system to visualize the small airways and alveoli of an intact mouse lung without fixation and dehydration, and analyzed their localized morphometric deformations between functional residual capacity (FRC) and total lung capacity (TLC). The maximum resolution of 32.6 lp/mm at the 5% modulation transfer function level can be achieved with 11.8-μm voxels and 7-min scanning. Compared with the values at FRC, the diameter and length for smaller airways (diameter at FRC <200 μm) increased by 68.8% and 29.5% (averaged value), and those for larger airways (diameter at FRC >400 μm) increased by 45.2 and 22.9% (averaged value), at TLC. Moreover we defined the volume behavior as the percentage of airway volume at FRC for TLC. The volume behavior for the small airways was not similar to that of the lung volume. These results indicated that all airways did not behave homogenously..
65. Toshihiro Sera, Kentaro Uesugi, Naoto Yagi,, Three-dimensional visualization of intact mouse lung by synchrotron radiation CT, Conference Proceeding of IEEE Engineering in Medicine and Biology Society, 2004.09.
66. Toshihiro Sera, Hideki Fujioka, Hideo Yokota, Akitake Makinouchi, Ryutaro Himeno, Robert C. Schroter, Kazuo Tanishita, Localized compliance of small airways in excised rat lungs using microfocal X-ray computed tomography, Journal of Applied Physiology, 10.1152/japplphysiol.00624.2003, 96, 5, 1665-1673, 2004.05, Airway compliance is a key factor in understanding lung mechanics and is used as a clinical diagnostic index. Understanding such mechanics in small airways physiologically and clinically is critical. We have determined the "morphometric change" and "localized compliance" of small airways under "near"-physiological conditions; namely, the airways were embedded in parenchyma without dehydration and fixation. Previously, we developed a two-step method to visualize small airways in detail by staining the lung tissue with a radiopaque solution and then visualizing the tissue with a cone-beam microfocal X-ray computed tomography system (Sera et al. J Biomech 36: 1587-1594, 2003). In this study, we used this technique to analyze changes in diameter and length of the same small airways (∼150 μm ID) and then evaluated the localized compliance as a function of airway generation (Z). For smaller (<300-μm-diameter) airways, diameter was 36% larger at end-tidal inspiration and 89% larger at total lung capacity; length was 18% larger at end-tidal inspiration and 43% larger at total lung capacity than at functional residual capacity. Diameter, especially at smaller airways, did not behave linearly with V1/3 (where V is volume). With increasing lung pressure, diameter changed dramatically at a particular pressure and length changed approximately linearly during inflation and deflation. Percentage of airway volume for smaller airways did not behave linearly with that of lung volume. Smaller airways were generally more compliant than larger airways with increasing Z and exhibited hysteresis in their diameter behavior. Airways at higher Z deformed at a lower pressure than those at lower Z. These results indicated that smaller airways did not behave homogeneously..
67. Toshihiro Sera, Hideki Fujioka, Hideo Yokota, Akitake Makinouchi, Ryutaro Himeno, Robert C. Schroter, Kazuo Tanishita, Three-dimensional visualization and morphometry of small airways from microfocal X-ray computed tomography, Journal of Biomechanics, 10.1016/S0021-9290(03)00179-9, 36, 11, 1587-1594, 2003.11, Physiological morphometry is a critical factor in the flow dynamics in small airways. In this study, we visualized and analyzed the three-dimensional structure of the small airways without dehydration and fixation. We developed a two-step method to visualize small airways in detail by staining the lung tissue with a radiopaque solution and then visualizing the tissue with a cone-beam microfocal X-ray computed tomographic (CT) system. To verify the applicability of this staining and CT imaging (SCT) method, we used the method to visualize small airways in excised rat lungs. By using the SCT method to obtain continuous CT images, three-dimensional branching and merging bronchi ranging from 500 to 150μm (the airway generation=8-16) were successfully reconstructed. The morphometry of the small airways (diameter, length, branching angle and gravity angle between the gravity direction and airway vector) was analyzed using the three-dimensional thinning algorithm. The diameter and length exponentially decreased with the airway generation. The asymmetry of the bifurcation decreased with generation and one branching angle decided the other pair branching angle. The SCT method is the first reported method that yields faithful high-resolution images of soft tissue geometry without fixation and the three-dimensional morphometry of small airways is useful for studying the biomechanical dynamics in small airways..
68. Toshihiro Sera, Sunao Satoh, Hirohisa Horinouchi, Koichi Kobayashi, Kazuo Tanishita, Respiratory flow in a realistic tracheostenosis model, Journal of Biomechanical Engineering, 10.1115/1.1589775, 125, 4, 461-471, 2003.08, The possible mechanism of wheeze generation in tracheostenosis was identified by measuring inspiratory and expiratory flow in a "morphological and distensible" realistic tracheostenosis model. The shape of the model was based on CT (Computed Tomography) images of a patient that had tracheostenosis. A trachea consists of tracheal cartilage rings and smooth muscle. Spatial variation of wall distensibility was achieved in the model by varying the wall thickness based on the elastic modulus measured in pig air-ways. The spatial variation influenced the flow in the airway and the turbulence production rate decreased faster at smooth muscles. Using the model, we investigated the mechanism of wheeze generation by focusing on the turbulence intensity. The turbulence intensity in expiratory flow was about twice that in inspiratory flow, and larger vortices existed in post-stenosis in expiratory flow, and thus might contribute to wheeze generation..
69. Toshihiro Sera, Hideki Fujioka, Hideo Yokota, Akitake Makinouchi, Ryutaro Himeno, Robert C. Schroter and Kazuo Tanishita,, Three-dimensional Visualization and Morphometry of Small Airways from Microfocal X-ray Computed Tomography, Proceedings of 2001 ASME Bioengineering Conference , 2003.07.
70. Toshihiro Sera, Yuji Hasegawa, Robert C. Schroter, and Kazuo Tanishita, , Three-Dimensional Analysis of Small Airway with X-Ray Micro-CT, Proceedings of 2001 ASME Bioengineering Conference, 2001.07.
71. Toshihiro Sera, Sunao Satoh, Hirohisa Horinouchi, Kohichi Kobayashi, Kazuo Tanishita, The inspiratory and expiratory flow in distensible tracheostenosis model, American Society of Mechanical Engineers, Bioengineering Division (Publication) BED, 48, 233-234, 2000.12, To identify the possible mechanism of wheeze generation in the tracheostenosis, we measured the inspiratory and expiratory flow in the realistic model reconstructed based on CT data of patient. Trachea consists of tracheal cartilage rings and smooth muscle, which influence the localized variation of distensibility of model airway. The localized variation of distensibility was achieved by the varied thickness of silicone rubber based on the elastic modulus measured for the pig airway. The Reynolds number was 1100, and both inspiratory and expiratory flow were disturbed by the stenosis. The turbulence intensity for the distensible model is moderated compared the rigid model..
72. Toshihiro Sera, Sunao Satoh, Hirohisa Horinouchi, Koichi Kobayashi, and Kazuo Tanishita, The Inspiratory and Expiratory Flow in Distensible Tracheostenosis Model, Proceedings of 2000 ASME International Mechanical Engineering Conference and Exposition, 2000.12.