Sakai Koji, Yamada Kei, Akazawa Kentaro, Tazoe Jun, Yasuike Masashi, Nagano Hitomi, Ikeno Hiroyasu, Nakagawa Toshiaki
Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kajii-cho, Kawaramachi Hirokoji Agaru, Kamigyo-ku, Kyoto, Kyoto, 602-8566, Japan.
Jpn J Radiol. 2017 Jan;35(1):16-24. doi: 10.1007/s11604-016-0593-8. Epub 2016 Nov 2.
Q-space imaging (QSI) is a novel magnetic resonance imaging (MRI) technique that enables assessment of micro-structural changes of white matter. The acquisition time, however, is comparatively long to use for routine clinical assessment. Therefore, the present study investigated the clinically feasible b value combinations to measure the water molecular displacement probability density function (PDF) in healthy subjects.
The subjects consisted of five healthy volunteers (1 female and 4 male; 40.8 ± 13.2 years). All MRIs were examined at 1.5 T. The QSI was acquired using a single-shot echo-planar imaging and Δ/δ = 142/17 ms. The magnitude of the gradients was incremented in nine steps to reach a maximal b = 10,000 s/mm. The total acquisition time of this original QSI was 17.4 min. The feasibility of ten alternative b value combinations with the zero-filling or curve fitting technique was assessed. The mean diffusivities (MDs), kurtosis, and zero displacement probability (ZDP) were obtained, and these results were compared in manually segmented regions of interest.
There were alternative b value combinations with a 7.5-min acquisition time and with almost the same PDF.
A few alternative b value combinations with the curve fitting technique were found to be able to shorten the QSI acquisition for its clinical feasibility of MD and ZDP.
Q空间成像（QSI）是一种新型磁共振成像（MRI）技术，可用于评估白质的微观结构变化。然而，其采集时间相对较长，不便于常规临床评估。因此，本研究探讨了在健康受试者中测量水分子位移概率密度函数（PDF）的临床可行b值组合。
研究对象为5名健康志愿者（1名女性和4名男性；年龄40.8±13.2岁）。所有MRI检查均在1.5T磁场下进行。使用单次激发回波平面成像和Δ/δ=142/17ms采集QSI。梯度幅度分9步递增，以达到最大b=10000s/mm²。这种原始QSI的总采集时间为17.4分钟。评估了十种采用零填充或曲线拟合技术的替代b值组合的可行性。获得了平均扩散率（MD）、峰度和零位移概率（ZDP），并在手动分割的感兴趣区域中对这些结果进行了比较。
存在采集时间为7.5分钟且PDF几乎相同的替代b值组合。
发现一些采用曲线拟合技术的替代b值组合能够缩短QSI采集时间，以实现其在MD和ZDP方面的临床可行性。
