Weber T, Ziener C H, Kampf T, Herold V, Bauer W R, Jakob P M
Department of Experimental Physics 5, Julius-Maximilians-Universität Würzburg, Am Hubland, Würzburg, Germany.
Magn Reson Med. 2009 Apr;61(4):1001-6. doi: 10.1002/mrm.21848.
It had been previously shown that an idealized version of the two-wave-vector extension of the NMR pulsed-field-gradient spin echo diffusion experiment can be used to determine the apparent radius of geometries with restricted diffusion. In the present work, the feasibility of the experiment was demonstrated in an NMR imaging experiment, in which the apparent radius of axons in white matter tissue was determined. Moreover, numerical simulations have been carried out to determine the reliability of the results. For small diffusion times, the radius is systematically underestimated. Larger gradient area, finite length gradient pulses, and a statistical distribution of radii within a voxel all have a minor influence on the estimated radius.
先前已经表明，核磁共振脉冲场梯度自旋回波扩散实验的两波矢扩展的理想化版本可用于确定具有受限扩散的几何结构的表观半径。在本工作中，该实验的可行性在核磁共振成像实验中得到了证明，其中确定了白质组织中轴突的表观半径。此外，还进行了数值模拟以确定结果的可靠性。对于较短的扩散时间，半径会被系统性低估。更大的梯度面积、有限长度的梯度脉冲以及体素内半径的统计分布对估计半径的影响都较小。
