脑梗死后皮质脊髓束Wallerian变性的DTI纵向研究

目的探讨应用扩散张量成像（DTI）观察脑梗死后从早期、亚急性至慢性期同侧皮质脊髓束（CST）的DTI参数随时间变化的规律，由此检测皮质脊髓束发生Wallerian变性的时间演变过程。方法选取2008年11月至2010年1月间在复旦大学附属中山医院住院治疗的皮层下运动通路脑梗死患者34例，发病时间从5h至2年。在入院时行MRI＋DTI检查。34例中选取5例患者，在发病1W内、第2周、1个月、3个月、6个月和1年分别行MRI＋DTI检查。采用工作站之Functool软件，重建出平均弥散系数（MD）、各向异性分数（FA）的参数图。通过放置兴趣区（ROI）的方式计算出FA值、MD值、rFA、rMD。ROI放置在双侧大脑脚。结果脑梗死后病灶同侧大脑脚区rFA在1月内下降最明显，1个月至3个月下降变慢，3个月后rFA变化幅度很小基本保持平稳。而rMD在脑梗死2W内无明显变化，2W至3个月上升，3个月后基本保持稳定。5例患者不同时间点的DTI研究能够显示这种变化过程。结论脑梗死后从早期、亚急性至慢性期同侧大脑脚处皮质脊髓束的FA值进行性减少。DTI有利于检测脑梗死后皮质脊髓束发生Wallerian变性的程度及动态演变过程。

A longitudinal study of diffusion tensor imaging on Wallerian degeneration of corticospinal tract in patients with cerebral infarction

Objective To study the changes of diffusion tensor imaging （DTI） indices in the degenerated ipsilateral corticospinal tract （CST） dynamically at the early, subacute and chronic stage after cerebral infarction attack. Methods Total 34 patients with motor pathway lesions were recruited and followed-up successfully from 5 hours to 2 years after cerebral infarction attack. All cases were assessed with DTI on admission. Of the all patients, 5 cases were performed repeatedly with DTI at the time of 1 week, 2 weeks, 1 month, 3 months, 6 months and 1 year after infarction attack. Quantitative FA and MD were obtained in region of interest （ROI） at the bilateral cerebral peduncle （CP）. The ratios of the fractional anisotropy （rFA） and mean diffusivity （rMD） were analysed statistically between the affected and unaffected side of the CSTs. Results The rFA was decreased obviously within the ？ rst month, decreased slowly from 1 month to 3 months after infarction attack, and remained stability relatively after 3 months. The rMD was not changed signi？ cantly within the ？ rst 2 weeks, and increased from 2 weeks to 3 months after infarction attack, then reached stability relatively after 3 months. The similar changes of DTI indices at different stage were showed in the selected 5 cases. Conclusions The FA value of the degenerated CST decreases gradually from early stage, subacute to chronic period after cerebral infar- ction. DTI may be an effective method to detect the state and time course of Wallerian degeneration in corticospinal tract after cerebral infarction.