K. Yamashita
Kyoto University
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by K. Yamashita.
American Journal of Cardiology | 1989
Nagara Tamaki; Yoshiharu Yonekura; K. Yamashita; Hideo Saji; Yasuhiro Magata; Michio Senda; Yutaka Konishi; Kazuo Hirata; Toshihiko Ban; Junji Konishi
To assess the clinical value of positron emission tomography (PET) in the evaluation of coronary artery bypass grafting (CABG), PET perfusion and metabolic imaging using nitrogen-13 ammonia and fluorine-18 deoxyglucose (FDG) was performed before and 5 to 7 weeks after CABG in 22 patients with coronary artery disease. Postoperative improvement in hypoperfusion was observed more often in the metabolically active segments (62%) than in the inactive segments (27%) on the preoperative PET study (p less than 0.05). Similarly, the postoperative lessening of wall motion abnormality was observed more often in the metabolically active segments (78%) than in the inactive segments (22%) (p less than 0.001). Of 19 asynergic segments showing increased FDG uptake before operation, the postoperative PET revealed a decrease in FDG uptake in 13 (68%) and persistent uptake in 6 (32%). The improvement in asynergy was observed in all the segments that showed a postoperative decrease in FDG uptake, but in only 50% of those with persistent uptake (p less than 0.01). On the other hand, 4 of 5 segments showing a new FDG uptake after operation revealed further wall motion abnormality. Furthermore, the segments metabolically active before operation were more likely to have patent grafts (95%) than the metabolically inactive segments (70%) (p less than 0.05). Thus, preoperative metabolic imaging using PET appears to be useful for predicting the response to CABG. Improvement in metabolic derangement was associated with improvement in regional function after CABG.
American Journal of Cardiology | 1988
Nagara Tamaki; Yoshiharu Yonekura; K. Yamashita; Michio Senda; Hideo Saji; Tetsuo Hashimoto; Tetsuro Fudo; Hirofumi Kambara; Chuichi Kawai; Toshihiko Ban; Junji Konishi
Myocardial viability in persistent thallium (TI)-201 defect is a controversial subject. To assess metabolic activity in segments with persistent defect, stress TI-201 tomography and positron emission tomography using nitrogen-13 ammonia and fluorine-18 2-fluoro-deoxyglucose (FDG) were performed in 28 patients with healed myocardial infarction. The segments with TI-201 perfusion defect in electrocardiogram-determined infarcted areas were selected for assessment. Stress perfusion defect was detected in 61 segments by TI-201 tomography. Twenty-two patients (36%) showed transient defects with redistribution (group 1) and 39 showed persistent defects (group 2). Increase in FDG uptake was observed in 95% in group 1. Among group 2 patients, 15 segments (38%) showed an increase in FDG uptake (group 2A) while the remaining 24 (62%) did not have an increased uptake (group 2B). The decrease in nitrogen-13 ammonia perfusion was more severe in group 2B (-23 +/- 7%) than in group 2A (-13 +/- 9%) (p less than 0.005) and group 1 (-10 +/- 4%) (p less than 0.001). In addition, wall motion scores tended to be lower in group 2B (0.21 +/- 0.71), compared with group 2A (0.67 +/- 0.70) (p = 0.05) and group 1 (0.77 +/- 0.60) (p less than 0.01). These data indicate that metabolic viability was observed in approximately 40% of the segments with persistent TI-201 defect. Preservation of regional perfusion and wall motion in these areas was similar to that in areas with transient TI-201 defect.
The Journal of Nuclear Medicine | 1991
Nagara Tamaki; Hiroshi Ohtani; K. Yamashita; Yasuhiro Magata; Yoshiharu Yonekura; Ryuji Nohara; Hirofumi Kambara; Chuichi Kawai; Kazuo Hirata; Toshihiko Ban
The Journal of Nuclear Medicine | 1989
Nagara Tamaki; Yoshiharu Yonekura; K. Yamashita; Michio Senda; Hideo Saji; Yutaka Konishi; Kazuo Hirata; Toshihiko Ban; Junji Konishi
Japanese Circulation Journal-english Edition | 1989
Hirofumi Kambara; Tetsuro Fudo; Tetsuo Hashimoto; Masataka Hayashi; Chuichi Kawai; Nagara Tamaki; K. Yamashita; Yoshiharu Yonekura; Junji Konishi
Japanese Circulation Journal-english Edition | 1991
Nagara Tamaki; Yoshiharu Yonekura; K. Yamashita; Yasuhiro Magata; Kazuo Hirata; Toshihiko Ban; Junji Konishi
Japanese Circulation Journal-english Edition | 1990
Hiroshi Ohtani; Nagara Tamaki; K. Yamashita; Yoshiharu Yonekura; Jyunji Konishi; Ryuji Nohara; Hirofumi Kambara; Chuichi Kawai; Kazuo Hirata; Toshihiko Ban
Japanese Circulation Journal-english Edition | 1990
Nagara Tamaki; Yoshiharu Yonekura; K. Yamashita; Hiroshi Ohtani; Jyunji Konishi; Ryuji Nohara; Takehiko Yamada; Hirofumi Kambara; Chuichi Kawai
Japanese Circulation Journal-english Edition | 1990
Hiroshi Ohtani; Nagara Tamaki; K. Yamashita; Yoshiharu Yonekura; Jyunji Konishi; Ryuji Nohara; Hirofumi Kambara; Chuichi Kawai; Kazuo Hirata; Toshihiko Ban
Japanese Circulation Journal-english Edition | 1989
Yoshiharu Yonekura; Nagara Tamaki; K. Yamashita; Hiroshi Ohtani; Junji Konishi; T. Fudo; Masataka Hayashi; Ryuji Nohara; Hirofumi Kambara; Chuichi Kawai