Ellingson Benjamin M, Kurpad Shekar N, Schmit Brian D
Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin 53201-1881, USA.
J Magn Reson Imaging. 2008 Nov;28(5):1068-79. doi: 10.1002/jmri.21578.
To characterize DTI metric changes throughout the length of the entire spinal cord from the acute through chronic stages of spinal cord injury (SCI).
Ex vivo DTI was performed at 9.4 Tesla to examine changes in water diffusion throughout the entire spinal cord (7-cm) up to 25 weeks after injury in a rat model of contusive SCI. Animals were grouped according to recovery times after injury (2, 5, 15, 20, or 25 weeks), and various DTI metrics were evaluated including transverse and longitudinal apparent diffusion coefficient (tADC and lADC), mean diffusivity (MD), and fractional anisotropy (FA).
An overall decrease in lADC throughout the cord and decreases in MD remote from the lesion site were observed, along with an increase in tADC within fiber tracts throughout the recovery period. These trends were statistically significant at P<0.05 and were found in both white and gray matter regions. tADC and lADC distributions in fiber bundles extracted using DTI tractography were well fit by an exponential model (R=0.998) with time constants of 4.6 and 3.3 days, respectively.
Results from the current study support the hypothesis that the spinal cord undergoes continual changes during recovery from SCI.
描述脊髓损伤（SCI）从急性期到慢性期整个脊髓长度上扩散张量成像（DTI）指标的变化。
在9.4特斯拉场强下进行离体DTI，以检查在挫伤性SCI大鼠模型中损伤后长达25周整个脊髓（7厘米）内水扩散的变化。根据损伤后的恢复时间（2、5、15、20或25周）对动物进行分组，并评估各种DTI指标，包括横向和纵向表观扩散系数（tADC和lADC）、平均扩散率（MD）和各向异性分数（FA）。
观察到整个脊髓的lADC总体下降，远离损伤部位的MD下降，以及在整个恢复期纤维束内tADC增加。这些趋势在P<0.05时具有统计学意义，并且在白质和灰质区域均有发现。使用DTI纤维束成像提取的纤维束中tADC和lADC分布通过指数模型（R=0.998）拟合良好，时间常数分别为4.6天和3.3天。
本研究结果支持以下假设，即脊髓在SCI恢复过程中会持续发生变化。
