Study of DTI of Impairment of Cortical Spinal Tract by Cerebral Ischemia

Objective:To study the diffusion anisotropic features of white matter fibers of cerebral ischemic patients by using MR diffusion tensor imaging (DTI).To evaluate the relationship between the impairment degree of cortical spinal tract(CST) and muscular strength. Materials and Methods 9 patients with acute cerebral ischemic stroke and 9 volunteers were performed MR T1WI、T2WI and DTI using GE sina exite imaging system. For imaging processing,fiber tracking with the software of DTV-II,fractional anisotropy maps 、directionally encoded color maps and 3D tractography of bilateral CST of all patients were created. For volunteers,fractional anisotropy (FA) were measured in anterior capsular limb and posterior capsular limb. For infarction patients,fractional anisotropy were measured and compared between infarction lesions and corresponding contralateral normal regions. Hand motor function ability was evaluated with Brunstorm criteria.Results:In normal volunteers group,fractional anisotropy measurements in white matter regions were not significantly different. Reconctruction FA images and DEC maps can display main white fibers. In stroke patients group,The FA value in infarct area of white matter was significant lower than that in normal hemisphere(paired test,t=4.570,P0.001).The FA value in infarct area is related with muscular strength of contralateral hand(spearmen correlation,rs=0.888,P0.05). DTI shows that the CST were compression,displacement,translocation,and partial break. Conclusion:DTI can precisely showed the orientation and distribution of cerebral white matter fiber tracts,opening a new field for researching cerebral white matter fiber in vivo. DTI FA maps and DEC maps displayed the oriention and anisotropy of white matter fiber in infarct area. 3D fiber tract maps could display the status of pyramidal tract more stereotacticly,then has important value to clinical management and prognosis.