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1,234 results on '"Takahashi, Masao"'

3. Deep Learning-Based Identification of Echocardiographic Abnormalities From Electrocardiograms

Author

Fujiki, Goro, Kodera, Satoshi, Setoguchi, Naoto, Tanabe, Kengo, Miyaji, Kotaro, Kushida, Shunichi, Saji, Mike, Nanasato, Mamoru, Maki, Hisataka, Fujita, Hideo, Kato, Nahoko, Watanabe, Hiroyuki, Suzuki, Minami, Takahashi, Masao, Sawada, Naoko, Ando, Jiro, Sato, Masataka, Sawano, Shinnosuke, Katsushika, Susumu, Shinohara, Hiroki, Takeda, Norifumi, Fujiu, Katsuhito, Akazawa, Hiroshi, Morita, Hiroyuki, and Komuro, Issei

Published
2025
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13. 3-Fr steerable microcatheter system via the upper limb artery in RADPLAT for right maxillary cancer

Author

Takahashi, Masao, primary, Nakazawa, Ken, additional, Usami, Yoko, additional, Natsuyama, Yuki, additional, Tsukamoto, Yuichi, additional, Suzuki, Jun, additional, Asami, Shiho, additional, Inoue, Hitoshi, additional, Matsumura, Satoko, additional, Nakahira, Mitsuhiko, additional, Saito, Tetsu, additional, Kato, Shingo, additional, Okada, Yoshitaka, additional, Tajima, Hiroyuki, additional, Kozawa, Eito, additional, and Baba, Yasutaka, additional

Published
2024
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17. Applying masked autoencoder-based self-supervised learning for high-capability vision transformers of electrocardiographies.

Author

Sawano, Shinnosuke, Kodera, Satoshi, Setoguchi, Naoto, Tanabe, Kengo, Kushida, Shunichi, Kanda, Junji, Saji, Mike, Nanasato, Mamoru, Maki, Hisataka, Fujita, Hideo, Kato, Nahoko, Watanabe, Hiroyuki, Suzuki, Minami, Takahashi, Masao, Sawada, Naoko, Yamasaki, Masao, Sato, Masataka, Katsushika, Susumu, Shinohara, Hiroki, and Takeda, Norifumi

Subjects
ARTIFICIAL neural networks, LEFT ventricular dysfunction, TRANSFORMER models, RECEIVER operating characteristic curves, UNIVERSITY hospitals, AUTOENCODER
Abstract

The generalization of deep neural network algorithms to a broader population is an important challenge in the medical field. We aimed to apply self-supervised learning using masked autoencoders (MAEs) to improve the performance of the 12-lead electrocardiography (ECG) analysis model using limited ECG data. We pretrained Vision Transformer (ViT) models by reconstructing the masked ECG data with MAE. We fine-tuned this MAE-based ECG pretrained model on ECG-echocardiography data from The University of Tokyo Hospital (UTokyo) for the detection of left ventricular systolic dysfunction (LVSD), and then evaluated it using multi-center external validation data from seven institutions, employing the area under the receiver operating characteristic curve (AUROC) for assessment. We included 38,245 ECG-echocardiography pairs from UTokyo and 229,439 pairs from all institutions. The performances of MAE-based ECG models pretrained using ECG data from UTokyo were significantly higher than that of other Deep Neural Network models across all external validation cohorts (AUROC, 0.913–0.962 for LVSD, p < 0.001). Moreover, we also found improvements for the MAE-based ECG analysis model depending on the model capacity and the amount of training data. Additionally, the MAE-based ECG analysis model maintained high performance even on the ECG benchmark dataset (PTB-XL). Our proposed method developed high performance MAE-based ECG analysis models using limited ECG data. [ABSTRACT FROM AUTHOR]

Published
2024
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19. Optical bandedge of diluted magnetic semiconductors: difference between II-VI and III-V-based DMSs

Author

Takahashi, Masao

Subjects
Condensed Matter - Materials Science
Abstract

Applying the dynamical coherent potential approximation to a simple model, we have theoretically studied the behavior of the optical bandedge in diluted magnetic semiconductors (DMSs). For $A^{\rm II}_{1-x}$Mn$_{x}B^{\rm VI}$-type DMS, the present study reveals that the linear relationship between exchange-spitting $\mit\Delta E_{ex} $ and the averaged magnetization $|x < S_z >|$ widely holds for different values of $x$. The ratio, $\mit\Delta E_{ex}/x < S_z>$, however, depends not only the exchange strength but also the band offset. Furthermore, the present study reveals that in the low dilution of Ga$_{1-x}$Mn$_x$As the optical bandedge exists not at the bandedge of the impurity band but near the bottom of host band. The optical bandedge behaves as if the exchange interaction is ferromagnetic although the antiferromagnetic exchange interaction actually operates at Mn site. We conclude that the spin-dependent shift of the carrier states between the impurity band and host band accompanying with the change of magnetization causes the apparently ferromagnetic behavior of the optical bandedge which was reported in the magnetoreflection measurement of Ga$_{1-x}$Mn$_x$As., Comment: 15page, 11 figures(Lack 7Figures) If you want to get perfect version, please contact the author

Published
2003

20. Carrier States and Ferromagnetism in Diluted Magnetic Semiconductors

Author

Takahashi, Masao and Kubo, Kenn

Subjects
Condensed Matter - Materials Science
Abstract

Applying the dynamical coherent potential approximation to a simple model, we have systematically studied the carrier states in $A_{1-x}$Mn$_xB$-type diluted magnetic semiconductors (DMS's). The model calculation was performed for three typical cases of DMS's: The cases with strong and moderate exchange interactions in the absence of nonmagnetic potentials, and the case with strong attractive nonmagnetic potentials in addition to moderate exchange interaction. When the exchange interaction is sufficiently strong, magnetic impurity bands split from the host band. Carriers in the magnetic impurity band mainly stay at magnetic sites, and coupling between the carrier spin and the localized spin is very strong. The hopping of the carriers among the magnetic sites causes ferromagnetism through a {\it double-exchange (DE)-like} mechanism. We have investigated the condition for the DE-like mechanism to operate in DMS's. The result reveals that the nonmagnetic attractive potential at the magnetic site assists the formation of the magnetic impurity band and makes the DE-like mechanism operative by substantially enhancing the effect of the exchange interaction. Using conventional parameters we have studied the carrier states in Ga$_{1-x}$Mn$_x$As. The result shows that the ferromagnetism is caused through the DE-like mechanism by the carriers in the bandtail originating from the impurity states., Comment: 20 pages, 14 figures

Published
2003
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22. Deep Learning Models for Predicting Left Heart Abnormalities From Single-Lead Electrocardiogram for the Development of Wearable Devices

Author

Sato, Masataka, primary, Kodera, Satoshi, additional, Setoguchi, Naoto, additional, Tanabe, Kengo, additional, Kushida, Shunichi, additional, Kanda, Junji, additional, Saji, Mike, additional, Nanasato, Mamoru, additional, Maki, Hisataka, additional, Fujita, Hideo, additional, Kato, Nahoko, additional, Watanabe, Hiroyuki, additional, Suzuki, Minami, additional, Takahashi, Masao, additional, Sawada, Naoko, additional, Yamasaki, Masao, additional, Sawano, Shinnosuke, additional, Katsushika, Susumu, additional, Shinohara, Hiroki, additional, Takeda, Norifumi, additional, Fujiu, Katsuhito, additional, Daimon, Masao, additional, Akazawa, Hiroshi, additional, Morita, Hiroyuki, additional, and Komuro, Issei, additional

Published
2023
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24. Different Home Blood Pressure Thresholds to Predict Perfect 24-Hour Ambulatory Blood Pressure Control in Treated Hypertension Based on an “All-in-One” Device

Author

Kario, Kazuomi, primary, Tomitani, Naoko, additional, Hoshide, Satoshi, additional, Nishizawa, Masafumi, additional, Yoshida, Tetsuro, additional, Kabutoya, Tomoyuki, additional, Fujiwara, Takeshi, additional, Mizuno, Hiroyuki, additional, Okawara, Yukie, additional, Kanegae, Hiroshi, additional, Nakagawa, Naoki, additional, Matsuoka, Yasufumi, additional, Kakuta, Hiroshi, additional, Hagiwara, Shinichi, additional, Komori, Takahiro, additional, Ogata, Yukiyo, additional, Yokoyama, Yasuhiro, additional, Kono, Ken, additional, Ishibashi, Kazuyo, additional, Tanaka, Ryota, additional, Watanabe, Tomonori, additional, Okada, Kenta, additional, Oba, Yusuke, additional, Harada, Kenji, additional, Ogoyama, Yukako, additional, Imai, Yasushi, additional, Shimizu, Hayato, additional, Taki, Mizuri, additional, Takahashi, Masao, additional, Higaki, Ayuho, additional, Shimpo, Masahisa, additional, Yokota, Ayako, additional, Funayama, Hiroshi, additional, Watanabe, Hiroaki, additional, Toriumi, Shinichi, additional, Shinohara, Hajime, additional, Eguchi, Kazuo, additional, Ishiyama, Yusuke, additional, Ono, Akifumi, additional, Ubukata, Satoshi, additional, Kemi, Yuta, additional, Suzuki, Daisuke, additional, Okazaki, Osamu, additional, Iuchi, Hiroyuki, additional, Sekizuka, Hiromitsu, additional, Haimoto, Koki, additional, Tanaka, Eiichiro, additional, Abe, Yasuhisa, additional, Katsuya, Abe Internal Medicine Clinic; Tomohiro, additional, Kato, Yoshiro, additional, Yoshinaga, Ryo, additional, Ando, Shinichi, additional, Kadokami, Toshiaki, additional, Ueda, Shin, additional, Narita, Keisuke, additional, Sato, Tomohide, additional, Kunitomo, Kotaro, additional, Ishihara, Kazuaki, additional, and Nakazato, Jun, additional

Published
2023
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26. Association between the ratio of serum n-3 to n-6 polyunsaturated fatty acids and acute coronary syndrome in non-obese patients with coronary risk factor: a multicenter cross-sectional study

Author

Nishizaki, Yuji, Shimada, Kazunori, Tani, Shigemasa, Ogawa, Takayuki, Ando, Jiro, Takahashi, Masao, Yamamoto, Masato, Shinozaki, Tomohiro, Miyazaki, Tetsuro, Miyauchi, Katsumi, Nagao, Ken, Hirayama, Atsushi, Yoshimura, Michihiro, Komuro, Issei, Nagai, Ryozo, and Daida, Hiroyuki

Published
2020
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34. Trans‐aortic mitral isthmus ablation after surgical patch closure for an atrial septal defect.

Author

Arai, Tomoyuki, Kujiraoka, Hirofumi, Yamaoka, Koichiro, Takahashi, Masao, Hojo, Rintaro, and Fukamizu, Seiji

Subjects
MITRAL valve insufficiency, ECHOCARDIOGRAPHY, RADIO frequency therapy, SURGICAL complications, CATHETER ablation, ATRIAL fibrillation, ATRIAL flutter, ATRIAL septal defects, ELECTROPHYSIOLOGY, TREATMENT effectiveness, HEART atrium, TACHYCARDIA, ELECTROCARDIOGRAPHY, COMPUTED tomography
Abstract

Introduction: In patients with prior atrial septal defect (ASD) closure and atrial tachyarrhythmias, transseptal puncture can be challenging. Methods and Results: This case report discusses a 65‐year‐old man who had previously undergone pulmonary vein isolation (PVI) and cavo‐tricuspid isthmus ablation for atrial fibrillation before ASD closure, respectively. He developed atrial tachycardia (AT) and underwent catheter ablation. AT was diagnosed as peri‐mitral flutter and the mitral isthmus (MI) linear ablation via a trans‐aortic approach successfully terminated it. Conclusion: This case demonstrates the feasibility and safety of transaortic MI linear ablation in patients with ASD closure devices or anatomical challenges when transseptal puncture is difficult. [ABSTRACT FROM AUTHOR]

Published
2024
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35. Cryoballoon ablation of peri-mitral atrial flutter refractory to radiofrequency ablation: a case report.

Author

Takahashi, Masao, Kujiraoka, Hirofumi, Arai, Tomoyuki, Hojo, Rintaro, and Fukamizu, Seiji

Subjects
ATRIAL flutter, CATHETER ablation, REFRACTORY materials
Abstract

Background The radiofrequency catheter ablation of peri-mitral atrial flutter is occasionally difficult, mostly due to epicardial or intramural conduction on the mitral isthmus (MI). However, cryoballoon ablation (CBA) of peri-mitral atrial flutter refractory to radiofrequency ablation has not been reported. Case summary We report a case of a 66-year-old male patient who experienced a recurrence of atypical atrial flutter and underwent the sixth catheter ablation. The activation and entrainment maps showed that this atypical atrial flutter (AFL) was peri-mitral AFL via pathways other than endocardial conduction in the MI. Previous radiofrequency catheter ablation attempts on the MI line, including endocardial, coronary sinus, and epicardial ablations, failed to achieve a bidirectional block of the MI. In this case, we selected CBA for the MI area and successfully achieved a bidirectional block of the MI. Discussion Although using CBA in the MI is off-label, it could be safely implemented using CARTOUNIVU™. We attributed the success of the bidirectional block of the MI in this case to the crimping of the northern hemisphere of the CBA to the mitral isthmus area, which resulted in the formation of a broad, uniform, and deep ablation lesion site. [ABSTRACT FROM AUTHOR]

Published
2024
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42. T‐wave oversensing after implantation of pacemakers with automatic sensitivity adjustment in patients with atrioventricular block.

Author

Takahashi, Masao, Kujiraoka, Hirofumi, Arai, Tomoyuki, Hojo, Rintaro, and Fukamizu, Seiji

Subjects
*ELECTROCARDIOGRAPHY, *HIS bundle, *HEART block, *CARDIAC pacing, *CARDIAC pacemakers
Abstract

T‐wave oversensing in pacemakers is rare because the set sensitivity is generally fixed. However, several models of pacemaker employ automatic sensitivity adjustment. Here, we present two cases of atrioventricular block treated by implantation of the pacemaker with automatic sensitivity adjustment. After implanting the pacemaker with automatic sensitivity adjustment, ventricular pacing suppression due to T‐wave oversensing occurred. In both cases, T‐wave oversensing disappeared after adjusting the setting sensitivity from 0.9 to 2.0 mV. [ABSTRACT FROM AUTHOR]

Published
2024
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46. Event Monitoring and Evaluation by Community Pharmacists in Japan: A Pilot Study on Fenofibrate and Pemafibrate

Author

Ooba, Nobuhiro, primary, Takahashi, Masao, additional, Nagamura, Marina, additional, Ushida, Makoto, additional, Kawakami, Eiji, additional, Kimura, Masaomi, additional, Sato, Tsugumichi, additional, Takahashi, Yoshinori, additional, Tokuyoshi, Junichi, additional, Hashiba, Hajime, additional, Kamei, Miwako, additional, Miyazaki, Choichiro, additional, and Shimada, Mitsuaki, additional

Published
2022
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