Fenyes D A, Narayana P A
Department of Radiology, The University of Texas at Houston Medical School, Houston, Texas 77030, USA.
Magn Reson Med. 1999 Aug;42(2):300-6. doi: 10.1002/(sici)1522-2594(199908)42:2<300::aid-mrm12>3.0.co;2-9.
The in vivo apparent diffusion tensor (ADT) of spinal cord was measured in nine rats at 2.0 T using an interleaved multi-shot echo planar imaging (EPI) diffusion sequence. A technique that combines sliding acquisition and phase correction, based on a calibration scan, to reduce ghosting artifacts in the images introduced by the strong diffusion-sensitizing gradients was described. Two rotationally invariant parameters, the trace (actually trace/3, to be consistent with the published values) and the lattice anisotropy index (LAI) were estimated from the ADT. In in vivo cords, the mean white matter (WM) trace value (1.05 +/- 0.13 x 10(-3) mm(2)/sec) was found to be significantly higher than the gray matter (GM) trace (0. 84 +/- 0.12 x 10(-3) mm(2)/sec, p < 0.0025). Significant anisotropic diffusion was observed in both WM and GM, with greater anisotropy in the WM (LAI=0.59 +/- 0.04) than in the GM (LAI=0.47 +/- 0.06, p < 0. 0001). These results are in agreement with the in vivo values determined using the conventional spin-echo sequence. Magn Reson Med 42:300-306, 1999.
采用交错多激发回波平面成像（EPI）扩散序列，在2.0T磁场下对9只大鼠的脊髓进行了活体表观扩散张量（ADT）测量。描述了一种基于校准扫描，结合滑动采集和相位校正的技术，以减少由强扩散敏感梯度引入的图像中的重影伪影。从ADT估计了两个旋转不变参数，迹（实际上是迹/3，以与已发表的值一致）和晶格各向异性指数（LAI）。在活体脊髓中，发现白质（WM）的平均迹值（1.05±0.13×10-3mm2/sec）显著高于灰质（GM）的迹值（0.84±0.12×10-3mm2/sec，p<0.0025）。在WM和GM中均观察到显著的各向异性扩散，WM中的各向异性（LAI=0.59±0.04）大于GM中的各向异性（LAI=0.47±0.06，p<0.0001）。这些结果与使用传统自旋回波序列测定的活体值一致。《磁共振医学》42:300 - 306，1999年。
