脑梗死后锥体束华勒变性的弥散张量成像

目的 应用弥散张量成像(DTI)探讨脑梗死后锥体束华勒变性(WI))弥散参数的变化规律及其早期变化与神经功能的关系.方法 选取2006年3月至2007年1月收入我院神经内科病房的急性(发病7 d内)脑梗死患者15例,男性13例,女性2例.于发病后7 d内、14 d分别进行DTI检查和美国国立卫生研究院腩卒中评分(NIHSS)、日常生活能力指数(BI)、修正的Rankin评分(mRS)、运动功能指数(MI)等神经功能评分.用西门子Trio 3.0T MR机采集DTI数据,由DTI Studio软件处理分析数据.计算出平均弥散系数(MD)、部分各向异件(FA)、第一本征值(λ1)、第二本征值(λ2)和第三本征值(λ3)的参数图.结果 发病14 d时的神经功能评分,NIHSS:6.93±3.39,BI:45.33±26.01,mRS:4.33±0.90,MI:69.47±60.71.发病14 d时病灶侧与健侧DTI指标比较,从大脑脚到延髓各个感兴趣区,脑桥中部的MD和延髓上部的MD两侧差异无统计学意义,其余病灶侧与健侧差异均有统计学意义.病灶侧的MD较健侧下降,病灶侧的FA较健侧减小,λ1较健侧降低,λ2和λ3较健侧增加.发病后14 d的DTI指标与NIHSS呈负相关(r=-0.613,P=0.015),与BI呈正相关(r=0.530,P=0.042),与MI呈正相关(r=0.543,P=0.036).结论 DTI可以检测脑梗死后第2周的脑桥锥体束WD,其表现为λ1下降、λ2和λ3升高、FA降低,尤其是后者与运动功能障碍相关.

Diffusion tensor imaging in detection of Wallerian degeneration of pyramidal tract after cerebral infarction

Objective To investigate the evolution of diffusion indices in the pyramidal tract with Wallerian degeneration(WD)due to cerebral infarction using diffusion tensor imaging(DTI),and to study the relationship between early changes of diffusion indices and motor deficit.Methods Fifteen patients (13 males and 2 females)with acute cerebral infarction(within 7 days)were recruited from the Neurology Department from Mar 2006 to Jan 2007.A11 patients were assessed with DTI.National Institutes of Health Stroke Scale(NIHSS),Bathel Index(BI),modified Rankin Scale(mRS)and Motricity Index(MI)within 7 days from onset,and at the second week.DTI was performed with SIEMENS Trio 3.0 T MR scanner.The placement of region of interest(ROI),measurement of diffusion indices were performed by DTI Studio software.The mean diffusivity(MD),the fractional anisotropy(FA),the first eigenvalue (λ1),the second eigenvalue(λ2),and the third eigenvalue(λ3)were computed.Results At the second week.NIHSS was 6.93±3.39.BI 45.33±26.01,mRS 4.33±0.90.and MI 69.47± 60.71.At the second week from onset.MD of the pyramidal tract at the levels of the middle slice of pons and the superior slice of medulla oblongata showed no significant differences between both the two sides at second week from onset. Other ROI showed significant differences between both sides.MD.FA and λ1 of affected side were lower than the unaffected side.λ2 and λ3 of the affected side were higher than the unaffected side.Positive correlations were found between FA and BI(r=0.530,P=0.042),FA and MI(r=0.543,P=0.036)at the second week.Negative correlations were found between FA and NIHSS(r=-0.613,P=0.015)at the second week.Conclusions DTI can detect the changes in the pyramidal tract due to WD within 7-14 days after ischemic stroke.including a decrease of the fractional anisotropy.the first eigenvalue and increased the second and the third eigenvalues.The fractional anisotropy of the second week from onset is related to the outcome of the motor function.