多发性硬化的正常表现脑白质的DTI定量

目的：应用磁共振弥散张量成像（DTI）技术，定量研究多发性硬化（MS）患者在常规磁共振上表现正常的脑白质（NAWM），以及探讨其相关的微观病理改变。材料和方法：采用3．0T磁共振仪，对34例Ms患者和25例性别年龄相匹配的正常志愿者均进行DTI检查。分别测量MS组和对照组的9个不同部位脑白质的平均弥散率（MD）和部分各向异性指数（FA值），这9个部位包括胼胝体膝部、体部、压部、内囊后肢、侧脑室旁白质、额叶白质、顶叶白质、枕叶白质以及小脑中脚。比较两组NAWM之间的MD和FA值是否存在差异。结果：MS组的NAWM的MD值均高于对照组（P〈0．05），以胼胝体体部、内囊、侧脑室旁及额叶白质、顶叶白质、枕叶白质更为显著（P〈0．01）；MS组的FA值与对照组比较，胼胝体体部、顶叶白质、额叶白质、枕叶白质及内囊、侧脑室旁发现明显降低（P〈0．05），以后4个部位更为显著（P〈0．01），而胼胝体膝部、压部和小脑结合臂有降低趋势，但无统计学意义。结论：应用DTI定量研究可以探测到多发性硬化的NAWM所出现的微观病理改变，表现为水分子的平均弥散幅度明显升高，以幕上明显，并且胼胝体体部、内囊后肢等白质纤维明显失去正常的方向性。DTI在对白质损伤程度的量化评估中具有重要的价值。

Diffusion Tensor Imaging:Quantification of Normal- appearing White Matter in Multiple Sclerosis

Purpose:To quantify the microscopic damage in normal-appearing white matter(NAWM)in MS and to investigate the related pathologic changes by using diffusion tensor imaging(DTI).Materials and Methods:DTI of whole brain was performed in 34 patients with MS and 25 age-matched healthy volunteers.Mean diffusivity(MD)and fractional anisotropy(FA)of 9 different NAWM region were cal- culated for all participants.Results:MD in the MS group was increased in all regions of NAWM com- pared to controls(P<0.05),significantly higher in the body of corpus callosum(CC),internal capsule, periventricular WM,frontal WM,parietal WM and occipital WM(P<0.01).FA in the MS group was decreased in the body of corpus callosum,internal capsule,periventricular WM,frontal WM,parietal WM and occipital WM(P<0.05),the genu and splenium of CC,middle cerebellar peduncle showed a trend of lowering in FA value.Conclusion:This study provides insights into microscopic pathogenesis of NAWM in MS by using DTI,and quantitative analysis of DTI could be a useful method for evaluating the NAWM damage.