Komlosh M E, Horkay F, Freidlin R Z, Nevo U, Assaf Y, Basser P J
Section on Tissue Biophysics and Biomimetics, NICHD, NIH, Bethesda, MD 20892, USA.
J Magn Reson. 2007 Nov;189(1):38-45. doi: 10.1016/j.jmr.2007.07.003. Epub 2007 Jul 18.
A double Pulsed Gradient Spin Echo (d-PGSE) MR experiment was used to measure and assess the degree of local diffusion anisotropy in brain gray matter, and in a novel "gray matter" phantom that consists of randomly oriented tubes filled with water. In both samples, isotropic diffusion was observed at a macroscopic scale while anisotropic diffusion was observed at a microscopic scale, however, the nature of the resulting echo attenuation profiles were qualitatively different. Gray matter, which contains multiple cell types and fibers, exhibits a more complicated echo attenuation profile than the phantom. Since microscopic anisotropy was observed in both samples in the low q regime comparable to that achievable in clinical scanner, it may offer a new potential contrast mechanism for characterizing gray matter microstructure in medical and biological applications.
采用双脉冲梯度自旋回波（d-PGSE）磁共振实验来测量和评估脑灰质以及一种新型“灰质”模型中的局部扩散各向异性程度，该模型由充满水的随机取向管组成。在这两个样本中，宏观尺度上观察到各向同性扩散，而微观尺度上观察到各向异性扩散，然而，所得到的回波衰减曲线的性质在定性上是不同的。包含多种细胞类型和纤维的灰质表现出比模型更复杂的回波衰减曲线。由于在与临床扫描仪可实现的低q区域中，两个样本都观察到了微观各向异性，它可能为医学和生物学应用中灰质微观结构的表征提供一种新的潜在对比机制。
