Department of Mechanical, Aerospace and Structural Engineering, Washington University in St. Louis, St. Louis, Missouri 63110, USA.
J Neurotrauma. 2010 Jan;27(1):253-62. doi: 10.1089/neu.2009.1026.
In vivo diffusion tensor imaging (DTI) derived indices have been demonstrated to quantify accurately white-matter injury after contusion spinal cord injury (SCI) in rodents. In general, a full diffusion tensor analysis requires the acquisition of diffusion-weighted images (DWI) along at least six independent directions of diffusion-sensitizing gradients. Thus, DTI measurements of the rodent central nervous system are time consuming. In this study, diffusion indices derived using the two-direction DWI (parallel and perpendicular to axonal tracts) were compared with those obtained using six-direction DTI in a mouse model of SCI. It was hypothesized that the mouse spinal cord ventral-lateral white-matter (VLWM) tracts, T8-T10 in this study, aligned with the main magnet axis (z) allowing the apparent diffusion coefficient parallel and perpendicular to the axis of the spine to be derived with diffusion-weighting gradients in the z and y axes of the magnet coordinate respectively. Compared with six-direction full tensor DTI, two-direction DWI provided comparable diffusion indices in mouse spinal cords. The measured extent of spared white matter after injury, estimated by anisotropy indices, using both six-direction DTI and two-direction DWI were in close agreement and correlated well with histological staining and behavioral assessment. The results suggest that the two-direction DWI derived indices may be used, with significantly reduced imaging time, to estimate accurately spared white matter in mouse SCI.
体内扩散张量成像（DTI）衍生指数已被证明可准确量化挫伤性脊髓损伤（SCI）后白质损伤。一般来说，完整的弥散张量分析需要采集沿至少六个独立的弥散敏感梯度方向的弥散加权图像（DWI）。因此，啮齿动物中枢神经系统的 DTI 测量耗时较长。在这项研究中，使用双方向 DWI（与轴突束平行和垂直）得出的扩散指数与 SCI 模型中使用六方向 DTI 得出的扩散指数进行了比较。研究假设，在本研究中，鼠脊髓腹外侧白质（VLWM）束 T8-T10 与主磁场轴（z）对齐，允许在 z 轴和 y 轴上的磁体坐标系中分别使用扩散加权梯度得出平行于和垂直于脊柱轴的表观扩散系数。与六方向全张量 DTI 相比，双方向 DWI 可在鼠脊髓中提供可比的扩散指数。使用六方向 DTI 和双方向 DWI 两种方法测量的损伤后保留白质的程度，通过各向异性指数进行估计，与组织学染色和行为评估非常吻合，相关性良好。结果表明，双方向 DWI 衍生指数可以在显著减少成像时间的情况下，准确估计 SCI 后保留的白质。
