白质纤维束磁共振扩散张量成像在恒河猴脑梗死模型中的应用

Application of diffusion tensor imaging of white matter fiber bundles in rhesus models of cerebral infarction

目的探讨MR扩散张量成像(DTI)及扩散张量纤维束成像(DTT)技术对恒河猴脑梗死模型脑缺血后不同时期白质纤维束损伤的诊断价值,并观察白质纤维束的受损情况。方法4只清洁级成年雄性恒河猴,平均年龄(8.0±1.5)岁,平均体质量(9.6±1.2)kg。采用恒河猴自体血栓制备大脑中动脉(M1段)闭塞-再通模型,闭塞后2.5 h予以重组组织型纤溶酶原激活剂溶栓治疗。分别于脑缺血后4 h、7 d、30 d进行常规MRI、扩散加权成像、DTI检查。对比梗死侧(梗死灶、额叶、小脑)与健侧相应部位脑白质的各向异性分数(FA)值和白质纤维束数量的改变。结果梗死侧梗死灶的FA及纤维束数量均具有7 d下降、30 d升高的趋势,差异均有统计学意义(缺血后4 h、7 d、30 d的FA分别为0.301±0.045、0.200±0.050、0.305±0.026,纤维束数量分别为43.0±1.6、22.8±11.0、31.3±6.4;F值分别为8.223、7.861,均P<0.05)。脑缺血后不同时间点梗死侧的额叶、小脑及对侧相应部位脑白质的FA和纤维束数量比较,差异均无统计学意义(均P>0.05)。结论DTI及DTT技术能较好地评价脑梗死恒河猴模型脑缺血后不同时期白质纤维束的损伤程度,对指导临床诊断和帮助判断预后有重要价值。

Objective To investigate the diagnostic value of MR diffusion tensor imaging(DTI)and diffusion tensor fiber bundle imaging(DTT)in white matter injury of cerebral infarction in different periods,and to observe the damage of white matter fiber bundles.Methods Four adult male rhesus monkeys,aging 8.0±1.5 years old and weighted 9.6±1.2 kg were experimented.Middle cerebral artery(M1 segment)embolization-reperfusion model was prepared by rhesus monkey autologous thrombosis and recanalization with recombinant tissue plasminogen activator 2.5 h after embolization.Routine magnetic resonance imaging(MRI),diffusion weighted imaging(DWI)and DTI were performed at 4 h,7 d and 30 d after surgery,respectively.The anisotropic coefficient(FA)values and changes of the white matter fiber bundles in corresponding parts of cerebral white matter between the infarcted side and the healthy side were compared.Results FA and the number of fiber bundles in the infarct side showed a trend of decrease on day 7 and increase on day 30 after ischemia,and the difference was statistically significant(At 4 h,7 d and 30 d after cerebral ischemia,FA was 0.301±0.045,0.200±0.050 and 0.305±0.026,respectively;The number of fiber bundles was 43.0±1.6,22.8±11.0 and 31.3±6.4,respectively.F values were 8.223 and 7.861,respectively;all P<0.05).At different time points after cerebral ischemia,FA and the number of fiber bundles in the frontal lobe and cerebellum of the infarcted side showed no statistical difference compared with the corresponding parts of the opposite side of the white matter(all P>0.05).Conclusion DTI and DTT can better evaluate the degree of white matter fiber bundle injury in cerebral infarction at different stages,which is of great value in guiding clinical diagnosis and predicting prognosis.