Komlosh M E, Lizak M J, Horkay F, Freidlin R Z, Basser P J
Section on Tissue Biophysics and Biomimetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-5772, USA.
Magn Reson Med. 2008 Apr;59(4):803-9. doi: 10.1002/mrm.21528.
A double-pulsed gradient spin echo (d-PGSE) filtered MRI sequence is proposed to detect microscopic diffusion anisotropy in heterogeneous specimen. The technique was developed, in particular, to characterize local microscopic anisotropy in specimens that are macroscopically isotropic, such as gray matter. In such samples, diffusion tensor MRI (DTI) produces an isotropic or nearly isotropic diffusion tensor despite the fact that the medium may be anisotropic at a microscopic length scale. Using d-PGSE filtered MRI, microscopic anisotropy was observed in a "gray matter" phantom consisting of randomly oriented tubes filled with water, as well as in fixed pig spinal cord, within a range of b-values that can be readily achieved on clinical and small animal MR scanners. These findings suggest a potential use for this new contrast mechanism in clinical studies and biological research applications.
提出了一种双脉冲梯度自旋回波（d-PGSE）滤波磁共振成像（MRI）序列，用于检测异质样本中的微观扩散各向异性。该技术尤其用于表征宏观各向同性的样本（如灰质）中的局部微观各向异性。在这类样本中，尽管介质在微观长度尺度上可能是各向异性的，但扩散张量MRI（DTI）会产生一个各向同性或近乎各向同性的扩散张量。使用d-PGSE滤波MRI，在由随机取向的充满水的管子组成的“灰质”模型以及固定的猪脊髓中，在临床和小动物MR扫描仪能够轻松实现的一系列b值范围内观察到了微观各向异性。这些发现表明这种新的对比机制在临床研究和生物研究应用中具有潜在用途。
