Yasuo Takehara

Ideographic characters call for extra processing to correspond with phonemes.

Cortical areas used in the copying of Japanese ideographic characters and syllabic characters were studied using functional magnetic resonance imaging in healthy volunteers. Complexity of characters was controlled to illustrate differences resulting from character to sound conversion differences between the ideographic and syllabic characters. Statistical comparisons indicated extensive activation in the fusiform gyrus, posterior portions around the intraparietal sulcus and in the conjunction area of BA 6, 9 and 44 (which is assumed to be Exners area) during the copying of ideographic characters. These findings suggested that indirectness between ideographic characters and their pronunciation demands extra processing such as semantic mediation and intensive grapheme processing in comparison with syllabic characters.

Four‐dimensional phase‐contrast vastly undersampled isotropic projection reconstruction (4D PC‐VIPR) MR evaluation of the renal arteries in transplant recipients: Preliminary results

To assess the performance of four‐dimensional phase‐contrast vastly undersampled isotropic projection reconstruction (4D PC‐VIPR) at 3.0T in depicting intrarenal arteries compared with computed tomography angiography (CTA), and its correlation with arterial flowmetry in comparison with Doppler ultrasonography (DUS).

Novel molecular targeted and wide spectrum antitumor agents: Preparation and preclinical evaluation of IER5/Cdc25B targeted low-molecular-weight phospha sugar derivatives

Hiroko Hasegawa, Mitsuji Yamashita,* Reiko Makita, Mayumi Yamaoka, Michio Fujie, Satoki Nakamura, Tatsuo Oshikawa, Junko Yamashita, Manabu Yamada, Mitsuru Kondo, Kazutaka Hirakawa, Mitsuo Toda, Yasuo Takehara, Kazunori Ohnishi, Haruhiko Sugimura, Sophie Laurent, and Robert N. Muller 1 Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561, Japan 2 Faculty of Medicine, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan 3 Department of Chemistry and Biochemistry, Numazu National College of Technology, Numazu 410-8501, Japan 4 Faculty of Medicine, University of Mons, Mons, Hainaut, Belgium

Hemodynamic vascular biomarkers for initiation of paraclinoid internal carotid artery aneurysms using patient-specific computational fluid dynamic simulation based on magnetic resonance imaging

PurposeWe performed computational fluid dynamics (CFD) for patients with and without paraclinoid internal carotid artery (ICA) aneurysms to evaluate the distribution of vascular biomarkers at the aneurysm initiation sites of the paraclinoid ICA.MethodsThis study included 35 patients who were followed up for aneurysms using 3D time of flight (TOF) magnetic resonance angiography (MRA) and 3D cine phase-contrast MR imaging. Fifteen affected ICAs were included in group A with the 15 unaffected contralateral ICAs in group B. Thirty-three out of 40 paraclinoid ICAs free of aneurysms and arteriosclerotic lesions were included in group C. We deleted the aneurysms in group A based on the 3D TOF MRA dataset. We performed CFD based on MR data set and obtained wall shear stress (WSS), its derivatives, and streamlines. We qualitatively evaluated their distributions at and near the intracranial aneurysm initiation site among three groups. We also calculated and compared the normalized highest (nh-) WSS and nh-spatial WSS gradient (SWSSG) around the paraclinoid ICA among three groups.ResultsHigh WSS and SWSSG distribution were observed at and near the aneurysm initiation site in group A. High WSS and SWSSG were also observed at similar locations in group B and group C. However, nh-WSS and nh-SWSSG were significantly higher in group A than in group C, and nh-SWSSG was significantly higher in group A than in group B.ConclusionOur findings indicated that nh-WSS and nh-SWSSG were good biomarkers for aneurysm initiation in the paraclinoid ICA.

MR Angiography of Aneurysm Models of Various Shapes and Neck Sizes

PURPOSE To investigate the signal intensity of lateral and terminal saccular aneurysm models with differing neck sizes using three-dimensional time-of-flight (TOF) MR angiography with various imaging parameters. METHODS The study included four lateral and four terminal saccular aneurysm models with pulsatile flow. The height and fundus diameter were 10 mm; the neck diameters were 2.5 mm, 5 mm, 7.5 mm, and 10 mm, respectively. Each aneurysm model was examined with fast imaging with steady-state precession MR sequences with parameters of 20-140/7 (repetition time/echo time) and flip angles of 10 degrees to 30 degrees. Signal intensity was measured and compared among the models. RESULTS Three-dimensional TOF MR angiography with the shorter repetition time and/or larger flip angle showed weaker signal intensity in the aneurysm models. Stronger signal intensity was obtained in the terminal saccular aneurysm models and/or the models with a wider neck than in the lateral saccular aneurysm models and/or the models with a narrower neck. In some aneurysm models, longer repetition times produced greater signal intensity than that of background brain models, but not in aneurysms with narrow necks. CONCLUSION Noncontrast 3-D TOF MR angiography delineated terminal saccular aneurysms and/or aneurysms with wider necks and did not delineate lateral saccular aneurysms and/or aneurysms with narrower necks. Longer repetition times are recommended to allow the spins flowing into the aneurysms to recover.