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136 results on '"Miyazaki, Shohei"'

7. Hemodynamic predictors of negative false lumen remodeling after frozen elephant trunk for acute aortic dissection.

Author

Takei, Yusuke, Miyazaki, Shohei, Suzuki, Kohei, Saito, Shunsuke, Oogaki, Hayato, Muraoka, Yuki, Ogasawara, Takeshi, Tezuka, Masahiro, Shibasaki, Ikuko, and Fukuda, Hirotsugu

Abstract

Objective: We evaluated the blood flow within the downstream aortic false lumen after frozen elephant trunk repair for acute aortic dissection and identified hemodynamic predictors of false lumen expansion and negative false lumen remodeling using four-dimensional flow magnetic resonance imaging. Methods: Thirty-one patients (Stanford type A, n = 28; Stanford type B, n = 3) with patent false lumen who underwent frozen elephant trunk procedures for acute aortic dissection were included in this observational study. Each patient underwent computed tomography during the follow-up period and four-dimensional flow magnetic resonance imaging within 3 postoperative months. The false lumen volumetric expansion rate was calculated using computed tomography data. The direction and the rate of flow in the lower descending aortic false lumen were analyzed. Negative false lumen remodeling was defined as a volumetric increase of > 10% from the baseline volume. Results: Negative false lumen remodeling had developed in 6 of the 31 patients during the observation period. Most of the false lumen flows were biphasic during systole. The range between peak and nadir flow rates was associated with the false lumen volumetric expansion rate (β coefficient = 6.77; p < 0.01, R2 = 0.43). Conclusions: The range between peak and nadir flow rates may serve as a hemodynamic predictor of negative false lumen remodeling, enabling further treatment for patients at risk of expansion in the downstream aorta. [ABSTRACT FROM AUTHOR]

Published
2024
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8. Reconstruction of right ventricular outflow tract stenosis and right ventricular failure after Ross procedure – comprehensive assessment of adult congenital heart disease with four-dimensional imaging: a case report

Author

Takigami, Masao, Itatani, Keiichi, Nakanishi, Naohiko, Morichi, Hiroko, Nishino, Teruyasu, Miyazaki, Shohei, Nakaji, Kosuke, Yamano, Michiyo, Kajiyama, Yo, Maeda, Yoshinobu, Matoba, Satoaki, Yaku, Hitoshi, and Yamagishi, Masaaki

Published
2020
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9. Analysis of the Optimum Tapering Angle in Microanastomosis Using Computational Fluid Dynamics

Author

Yagi, Shunjiro, Ikuta, Kento, Miyazaki, Shohei, Umeda, Ryunosuke, Kanayama, Haruka, A. Hifny, Mahmoud, Morita, Maki, Nakagaki, Makoto, Tanabe, Makoto, Suyama, Yoshiko, Fukuoka, Kohei, Yagi, Shunjiro, Ikuta, Kento, Miyazaki, Shohei, Umeda, Ryunosuke, Kanayama, Haruka, A. Hifny, Mahmoud, Morita, Maki, Nakagaki, Makoto, Tanabe, Makoto, Suyama, Yoshiko, and Fukuoka, Kohei

Abstract

Background: In free flap transfer, size discrepancy between the vascular pedicle and recipient vessel can create a problem for microsurgeons and sometimes induces postoperative thrombus formation. When there is a major difference between the diameters of the vascular pedicle and the recipient vessel, the larger vessel is often tapered to perform the anastomosis properly. However, the decision on the tapering angle used depends mostly on the operator’s experience. In this study, computational fluid dynamics (CFD) was used to investigate the optimum tapering angle. Methods: Using ANSYS ICEM 16.0 (ANSYS Japan, Tokyo, Japan), simulated vessels of diameters 1.5 mm and 3.0 mm were designed and then used to produce four anastomosis models with the 3.0-mm vessel tapered at angles of 15º, 30º, 60º, and 90º (no tapering). Venous perfusion with a mean value of 13.0 mL/min was simulated, and this was passed through the four anastomosis models in both the forward direction (F), from the smaller to the larger vessel, and the retrograde direction (R), from the larger to the smaller vessel. The velocity, wall shear stress (WSS), and oscillatory shear index (OSI) were measured in these eight patterns and then analyzed using OpenFOAM version 5. Results: The decrease in velocity was limiting. The WSS was greater in the R direction than the F direction at every tapering angle. The OSI also tended to be almost the same in the F direction, and lower at smaller tapering angles in the R direction. And, it was greater in the F direction than in the R direction at every tapering angle. The OSI values for 15º and 30º were almost identical in the R direction. Conclusion: The risk of thrombus formation is thought to be lower when tapering is used for anastomosis if the direction of flow is from the larger to the smaller vessel, rather than vice versa. These results also suggest that the optimum tapering angle is approximately 30º in both directions.

Published
2023

10. Blood flow kinetic energy is a novel marker for right ventricular global systolic function in patients with left ventricular assist device therapy

Author

Akiyama, Koichi, primary, Colombo, Paolo C., additional, Stöhr, Eric J., additional, Ji, Ruiping, additional, Wu, Isaac Y., additional, Itatani, Keiichi, additional, Miyazaki, Shohei, additional, Nishino, Teruyasu, additional, Nakamura, Naotoshi, additional, Nakajima, Yasufumi, additional, McDonnell, Barry J, additional, Takeda, Koji, additional, Yuzefpolskaya, Melana, additional, and Takayama, Hiroo, additional

Published
2023
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14. Analysis of the Optimum Tapering Angle in Microanastomosis Using Computational Fluid Dynamics

Author

Yagi, Shunjiro, Ikuta, Kento, Miyazaki, Shohei, Umeda, Ryunosuke, Kanayama, Haruka, A. Hifny, Mahmoud, Morita, Maki, Nakagaki, Makoto, Tanabe, Makoto, Suyama, Yoshiko, and Fukuoka, Kohei

Subjects
tapering, size discrepancy, Original Article, microsurgery, computational fluid dynamics, General Medicine, simulation
Abstract

Background: In free flap transfer, size discrepancy between the vascular pedicle and recipient vessel can create a problem for microsurgeons and sometimes induces postoperative thrombus formation. When there is a major difference between the diameters of the vascular pedicle and the recipient vessel, the larger vessel is often tapered to perform the anastomosis properly. However, the decision on the tapering angle used depends mostly on the operator’s experience. In this study, computational fluid dynamics (CFD) was used to investigate the optimum tapering angle. Methods: Using ANSYS ICEM 16.0 (ANSYS Japan, Tokyo, Japan), simulated vessels of diameters 1.5 mm and 3.0 mm were designed and then used to produce four anastomosis models with the 3.0-mm vessel tapered at angles of 15º, 30º, 60º, and 90º (no tapering). Venous perfusion with a mean value of 13.0 mL/min was simulated, and this was passed through the four anastomosis models in both the forward direction (F), from the smaller to the larger vessel, and the retrograde direction (R), from the larger to the smaller vessel. The velocity, wall shear stress (WSS), and oscillatory shear index (OSI) were measured in these eight patterns and then analyzed using OpenFOAM version 5. Results: The decrease in velocity was limiting. The WSS was greater in the R direction than the F direction at every tapering angle. The OSI also tended to be almost the same in the F direction, and lower at smaller tapering angles in the R direction. And, it was greater in the F direction than in the R direction at every tapering angle. The OSI values for 15º and 30º were almost identical in the R direction. Conclusion: The risk of thrombus formation is thought to be lower when tapering is used for anastomosis if the direction of flow is from the larger to the smaller vessel, rather than vice versa. These results also suggest that the optimum tapering angle is approximately 30º in both directions.

Published
2022
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19. Estimating the Haemodynamic Streamline Vena Contracta as the Effective Orifice Area Measured from Reconstructed Multislice Phase-contrast MR Images for Patients with Moderately Accelerated Aortic Stenosis

Author

Hohri, Yu, primary, Itatani, Keiichi, additional, Matsuo, Akiko, additional, Komori, Yoshiaki, additional, Okamoto, Takeshi, additional, Goto, Tomoyuki, additional, Kobayashi, Takuma, additional, Hiramatsu, Takeshi, additional, Miyazaki, Shohei, additional, Nishino, Teruyasu, additional, and Yaku, Hitoshi, additional

Published
2022
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20. NI-3 Magnetic resonance relaxometry for tumor cell density imaging for glioma: An exploratory study via 11C-methionine PET and its validation via stereotactic tissue sampling

Author

Kinoshita, Manabu, primary, Uchikoshi, Masato, additional, Tateishi, Souichiro, additional, Miyazaki, Shohei, additional, Sakai, Mio, additional, Ozaki, Tomohiko, additional, Asai, Katsunori, additional, Fujita, Yuya, additional, Matsuhashi, Takahiro, additional, Kanemura, Yonehiro, additional, Shimosegawa, Eku, additional, Hatazawa, Jun, additional, Nakatsuka, Shinichi, additional, Kishima, Haruhiko, additional, and Nakanishi, Katsuyuki, additional

Published
2021
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23. Magnetic Resonance Relaxometry for Tumor Cell Density Imaging for Glioma: An Exploratory Study via 11C-Methionine PET and Its Validation via Stereotactic Tissue Sampling

Author

Kinoshita, Manabu, primary, Uchikoshi, Masato, additional, Tateishi, Souichiro, additional, Miyazaki, Shohei, additional, Sakai, Mio, additional, Ozaki, Tomohiko, additional, Asai, Katsunori, additional, Fujita, Yuya, additional, Matsuhashi, Takahiro, additional, Kanemura, Yonehiro, additional, Shimosegawa, Eku, additional, Hatazawa, Jun, additional, Nakatsuka, Shin-ichi, additional, Kishima, Haruhiko, additional, and Nakanishi, Katsuyuki, additional

Published
2021
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28. NIMG-19. T1- AND T2-RELAXOMETRY FOR TISSUE CELL DENSITY QUANTIFICATION IN GLIOMA IMAGING: EXPLORATORY STUDY VIA 11C-METHIONINE PET AND VALIDATION VIA STEREOTACTIC TISSUE SAMPLING

Author

Kinoshita, Manabu, primary, Uchikoshi, Masato, additional, Tateishi, Souichiro, additional, Miyazaki, Shohei, additional, Sakai, Mio, additional, Ozaki, Tomohiko, additional, Asai, Katsunori, additional, Fujita, Yuya, additional, Matsuhashi, Takahiro, additional, Kanemura, Yonehiro, additional, Shimosegawa, Eku, additional, Hatazawa, Jun, additional, Nakatsuka, Shinichi, additional, Kishima, Haruhiko, additional, and Nakanishi, Katsuyuki, additional

Published
2019
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35. Pharmacokinetic model analysis of interaction between phenytoin and capecitabine

Author

Miyazaki, Shohei, primary, Satoh, Hiroki, additional, Ikenishi, Masayuki, additional, Sakurai, Miyuki, additional, Ueda, Mutsuaki, additional, Kawahara, Kaori, additional, Ueda, Rie, additional, Ohtori, Tohru, additional, Matsuyama, Kenji, additional, Miki, Akiko, additional, Hori, Satoko, additional, Fukui, Eiji, additional, Nakatsuka, Eitaro, additional, and Sawada, Yasufumi, additional

Published
2016
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