DTI及tractography对失写症书写中枢及相关结构的初步分析

DTI and tractography on cerebral cheirokinesthetic center and posterior internal capsule of agraphia

目的 扩散张量成像技术探讨失写症脑内神经纤维改变的特征。方法 失写症5例,SIEMENS Trio 2003T行常规MRI和扩散张量成像。结果 5例左侧额中回后部不同程度信号异常。DTI fiber tractography显示书写中枢纤维数量明显降低,尤其U形纤维明显,额叶脑回间、中央前回、Broca区的纤维联系明显减少,内囊后肢前部的纤维中断,书写中枢与内囊后肢前部间的关系松散。结论 失写症脑内纤维改变主要以额叶脑回间的 U形纤维的减少,书写中枢与内囊后肢前部间的纤维联系明显减少。

Objective To exhibit the fibers of cheirokinesthetic center, and to demonstrate fiber changes of agraphia with diffusion tensor imaging and fiber tracking technique. Methods Conventional MRI, diffusion tensor imaging (DTI) and fiber tractography were performed in 5 cases with agraphia by 3.0 T SIEMENS Trio 2003T MRI. Cheirokinesthetic center and contralateral normal areas were measured FA values, as seeds to track fibers. DTI method depicted the left cheirokinesthetic center's fibers. Results Conventional MRI demonstrated abnormal signal intensity on left posterior frontal middle gyrus. DTI fiber tractography exhibited left cheirokinesthetic center fibers decreased evidently, especially U-shaped fibers between adjacent frontal gyri. Fibers of posterior frontal middle gyrus with other frontal gyri, precentral gyrus and Broca's area decreased, especially with arm area of precentral gyrus. Foreside fibers of posterior internal capsule were broken,and the relationship between cheirokinesthetic center and foreside fibers of posterior internal capsule become loose. Conclusion Agraphia patient cerebral nerve fiber changes are U-shaped fibers decrease obviously, and the fibers between cheirokinesthetic and foreside fibers of posterior internal capsule decrease, too.