Analysis of partial volume effects in diffusion-tensor MRI
Analysis of partial volume effects in diffusion-tensor MRI
复制标题
DOI：
10.1002/mrm.1105
复制
发表时间：
2001-05-01
影响因子：
3.3
通讯作者：
Parker, DL
中科院分区：
文献类型：
--
作者：
Alexander, AL;Hasan, KM;Parker, DL
扩散张量是目前公认的生物组织扩散模型。当两个或多个具有不同扩散张量的不同组织占据同一体素时，所测量的扩散行为可能更加复杂。在这项研究中，提出了两个扩散张量室的MRI信号行为的部分体积模型。使用该模型的模拟表明，传统的单扩散张量模型可能会导致高度可变和不准确的扩散行为的测量。单张量模型和双张量模型之间的差异取决于两个扩散张量室之间的方向、分数和交换，以及测量中使用的扩散张量编码技术和扩散加权。当前单室模型的不准确性可能导致脑缺血和白色物质连接的基于扩散的表征不正确。在正常人脑上进行的扩散张量MRI成像实验显示，当使用非常大的体素和大的扩散加权（B类似于2.69 x 10（3）sec/mm（2））时，倾斜白色物质区域之间存在显著的部分体积效应。然而，当使用较小的体素尺寸时，白色物质中的表观部分体积效应显著降低。对于使用典型扩散加权值（B类似于1 x 103 sec/mm（2））获得的扩散张量研究，部分体积效应更难以检测和解决。多个扩散隔室的更准确测量可导致用于临床应用的扩散测量的置信度提高。(C)2001 Wiley-Liss，Inc.
The diffusion tenser is currently the accepted model of diffusion in biological tissues. The measured diffusion behavior may be more complex when two or more distinct tissues with different diffusion tensors occupy the same voxel, In this study, a partial volume model of MRI signal behavior for two diffusion-tenser compartments is presented. Simulations using this model demonstrate that the conventional single diffusion tenser model could lead to highly variable and inaccurate measurements of diffusion behavior. The differences between the single and two-tensor models depend on the orientations, fractions, and exchange between the two diffusion tenser compartments, as well as the diffusion-tenser encoding technique and diffusion-weighting that is used in the measurements. The current single compartment model's inaccuracies could cause diffusion-based characterization of cerebral ischemia and white matter connectivity to be incorrect. A diffusion-tenser MRI imaging experiment on a normal human brain revealed significant partial volume effects between oblique white matter regions when using very large voxels and large diffusion-weighting (b similar to 2.69 x 10(3) sec/mm(2)). However, the apparent partial volume effects in white matter decreased significantly when smaller voxel dimensions were used. For diffusion tenser studies obtained using typical diffusion-weighting values (b similar to 1 x 103 sec/mm(2)) partial volume effects are much more difficult to detect and resolve. More accurate measurements of multiple diffusion compartments may lead to improved confidence in diffusion measurements for clinical applications. (C) 2001 Wiley-Liss, Inc.