Takashi Minami

Publications (2)0 Total impact

• Article: [Analyses of restricted diffusion of water molecules using trabecular bone phantom].

  Takashi Minami, Tosiaki Miyati, Yu Ueda, Hirohito Kan, Akihiro Kitanaka, Harumasa Kasai, Nobuyuki Arai, Masaki Hara, Yuta Shibamoto, Shigeyoshi Yokoti
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  ABSTRACT: We have reported that the apparent diffusion coefficient (ADC) was correlated with bone mineral density, but the relation between the restricted diffusion of the water molecules and the trabecular bone structure was unclear. The purpose of our study is to clarify this relationship using two component analyses with an original phantom. With an increase in the interspace area of the simulated trabecular bone, the ADC of the fast component was increased, and the fraction of the fast component was also increased. On the other hand, with an increase in the interspace area of the simulated trabecular bone, the ADC of the slow component was decreased, and the fraction of the slow component was increased. Moreover, the ADC and fraction of the dry vertebral bone agreed with those of the simulated trabecular bone. This result means that our phantoms can reproduce the actual trabecular bone structure, which induces the restricted diffusion. The diffusion of the water molecules was separated into fast and slow components because of the restricted diffusion of the trabecular bone structure. Our original phantom enables analyzing restricted diffusion, and this analytical method obtains more detailed information on trabecular bone structure.
  Nippon Hoshasen Gijutsu Gakkai zasshi 01/2011; 67(6):634-9.
• Article: [Appropriate cardiac phase for measurement of ADC of the brain using ECG-triggered diffusion MRI].

  Hirohito Kan, Tosiaki Miyati, Mitsuhito Mase, Harumasa Kasai, Masaki Hara, Yuta Shibamoto, Makoto Kawano, Naoki Ohno, Akihiro Kitanaka, Risa Yorimitsu, Takashi Minami
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  ABSTRACT: Apparent diffusion coefficients (ADCs) are sometimes overestimated when they are measured in the brain near the basal ganglia because water molecules in brain tissues fluctuate with blood volume loading in the cranium. We determined detailed ADC changes during the cardiac cycle to evaluate the appropriate cardiac phases for accurate measurement of ADC values. Using 1.5 T MRI, we performed ECG-triggered single-shot EPI to obtain ADC maps in each cardiac phase using techniques minimizing the bulk motion effect. The coefficient of variation (CV) of the ADC values during the cardiac cycle was over 50% near the basal ganglia. Moreover, the cardiac phase of the peak ADC value during the cardiac cycle was from 10 to 40% cardiac phases that follow systole. However, the CV of the ADC values of whole cardiac phases was higher than those with phases over 50% of the cardiac cycle near the basal ganglia because the effect of water fluctuation was almost eliminated. Therefore, accurate measurement of ADC values should be obtained from ADC maps of phases over 50% of the cardiac cycle.
  Nippon Hoshasen Gijutsu Gakkai zasshi 01/2011; 67(6):661-5.