扩散张量成像在皮质脊髓束华勒变性中的应用

Application of Corticospinal Tract Wallerian Degeneration with Diffusion Tensor Imaging

目的利用扩散张量成像(DTI)研究皮质脊髓束(CST)不同程度华勒变性(WD)微结构变化特点及临床价值。方法回顾性分析我院47例单侧运动区脑梗死患者,依据CST信号和体积是否异常将WD分成三组,I组:CST白质纤维束无信号及形态学改变,共17例;Ⅱ组:CST白质纤维束呈高信号,但无萎缩,共12例;Ⅲ组:CST白质纤维束呈高信号伴萎缩,共18例。所有患者DTI数据经分析处理,在CST患侧和健侧内囊后支、大脑脚、中脑、延髓层面走行区获取FA、MD、λ_1、λ_(2+3)值,将各组WD不同部位健侧与患侧DTI各参数指标行t检验,将大脑脚层面神经生物学指标与NIHSS和MI评分行Spearman相关分析。结果 (1)Ⅰ组患侧与健侧皮质脊髓束λ_1有统计学差异(P<0.05),Ⅱ组患侧与健侧皮质脊髓束FA、MD、λ_(2+3)差异有统计学意义(P<0.05),Ⅲ组患侧与健侧皮质脊髓束FA、MD、λ_1、λ_(2+3)均有统计学差异(P<0.05)。(2)Ⅰ组患者大脑脚区CST rλ_1与NIHSS评分存在负相关(r=-0.747,P<0.01),rλ_1与运动力指数呈正相关(r=0.862,P<0.01)。结论 DTI判断CST WD的严重程度有一定特征,其中λ_1可以作为早期发现WD微结构变化以及评价病情严重程度的神经生物学指标。

Objective To study clinical value and characteristic microstructure of corticospinal tract（ CST） in different degrees of Wallerian degeneration using diffusion tensor imaging. Methods To analyse 47 patients with cerebral infarction in unilateral motor areas,retrospectively. Wallerian degeneration were divided into three groups on the basis of variation of CST signal and the volume. Group I（ 17 cases） ： There were no signal and morphologic changes in CST. GroupⅡ（ 12 cases） ： There was an appearance of hyperintensity of CST on T2 WI without shrinking. Group Ⅲ（ 18 cases） ： CST have characteristic of hyperintensity and atrophy on T2 WI. DTI data of all patients could be used for processing and analysis to obtain diffusion indices（ FA,MD,λ1,λ（2 ＋ 3）） of affected side and healthy side in the internal capsule,cerebral peduncle,the midbrain and the medulla oblongata of CST. Intra-group comparison was made using the t test for the affected and healthy side in different levels of CST. Spearman rank correlations were calculated between diffusion indices and NIHSS、MI. Results 1. There were significantly different in theλ1between affected and unaffected sides of CST（ P〈0. 05）. It showed significant differences in the FA、MD、λ（2 ＋ 3）between affected and unaffected sides of CST（ P〈0. 05）. There were statistical differences in the FA、MD、λ1、λ（2 ＋ 3）between affected and unaffected sides of CST. 2. Significant correlations between rλ1and clinical scores were found： rλ1was negatively correlated with the NIHSS in Ⅰ group（ r =- 0. 747,P〈0. 01）; Positive correlations were found between rλ1and the Motricity Index in Ⅰ group（ r = 0. 862,P〈0. 01）.Conclusion WD in the CST have characteristic appearance in DTI,λ1can be used in detecting the early Wallerian degeneration microstructure change and evaluation of disease severity.