Effects of diffusion time and diffusion gradient strength on the mean diffusivity of water molecules in healthy human brain  

作　　者：GAO Song WANG Xiaoying BAO Shanglian 

机构地区：[1]Laboratory of Medical Physics ＆ Engineering, Peking University, Beijing 100871, China [2]Department of Radiology, The First Affiliated Hospital of Peking University, Beijing 100034, China

出　　处：《Progress in Natural Science:Materials International》2006年第7期706-711,共6页自然科学进展·国际材料（英文版）

基　　金：Supported by National Natural Science Foundation of China (Grant No, 10527003)Joint Research Fund of Beijing (SYS100010401) The Research Fund for the Doctoral Program of Higher Education (20040001003)

摘　　要：Diffusion time and diffusion gradient strength are two important parameters of pulsed gradient spin echo （PGSE） that is the most commonly used method in diffusion-weighted magnetic resonance imaging. However, the effects of the diffusion time on the mean diffusivity （MD） in previous studies are controversial. In this study, a new experimental protocol was designed to evaluate the effects of the two parameters on the results of PGSE. It was found that MD decreased significantly with the increased diffusion time or increased diffusion gradient strength, which cannot be explained by the previous theories. Through theoretical analysis, we found the flaw in the pulsed gradient spin echo （PGSE） method, which is the explanation for the controversial results of diffusion time obtained by others.散开时间和散开坡度力量是是在散开加权的磁性的回声成像的最通常使用的方法的搏动的坡度旋转回响(PGSE ) 的二个重要参数。然而，在以前的研究的吝啬的扩散性(MD ) 上的散开时间的效果是争论的。在这研究，一个新试验性的协议被设计在 PGSE 的结果上评估二个参数的效果。与增加的散开时间显著地减少了或增加了散开坡度力量，被发现那 MD，它不能被以前的理论解释。通过理论，我们在搏动的坡度发现了缺陷旋转回响(PGSE ) 方法，它是对其它获得的散开时间的争论结果的解释。

关 键 词：diffusion time diffusion gradient strength diffusion-weighted imaging diffusion tensor imaging mean diffusivity. 

分 类 号：R445[医药卫生—影像医学与核医学]