脑缺血性卒中MR扩散张量成像的初步研究

Preliminary Study of Cerebral Ischemia by Difusion Tensor Imaging

目的利用磁共振扩散张量成像(DTI)及扩散张量纤维束成像(DTT)评价缺血性脑卒中所致皮质脊髓束(CST)损伤程度与运动功能的关系。方法对9例急性期大脑中动脉供血区缺血性脑卒中病人进行常规MR、DTI和DTT检查,对数据进行离线后处理,采用dTV.II软件处理,获得FA图及方向编码彩色图,并重建双侧皮质脊髓束3D纤维束图。对梗死区及健侧相应区域白质进行FA测量。采用Brunnstorm标准判断脑卒中患者患手肌力。结果在脑卒中病人梗死区FA值显著低于健侧,两侧相比差异有显著统计学意义(t=4.570,P<0.001)。病变侧皮质脊髓束表现为受压、变形、移位和中断,皮质脊髓束受累情况与肌力和运动功能的恢复有良好的相关性(rs=0.888,P<0.05)。结论CST损伤严重程度与运动功能的恢复相关,DTI和DTT对观察CST的损害程度、预测恢复程度、指导临床康复治疗具有重要的价值。

Objective To study the diffusion anisotropic features of white matter fibers of cerebral ischemie patients by using MRI diffusion tensor imaging （DTI） and diffusion tensor tractography （DTr） in order to evaluate the relationship between the impairment degree of cortical spinal tract （CST） and muscular strength. Methods Nine patients with acute cerebral ischemic stroke were performed MRI, DTI and DTT. For imaging processing, fiber tracking with the software of DTV-II, fractional anisotropy （FA） maps, directionally encoded color maps and 3D tractography of bilateral CST of all the patients were created. FA was measured and compared between infarction lesions and corresponding contralateral normal regions. Hand motor function ability was evaluated with Brunstorm criteria. Results In the stroke patients, FA value in the infarct area of white matter was significant lower than that in the normal hemisphere （ P 〈 0. 001 ）. FA value in the infarct area was related with muscular strength of contralateral h;,nd （ P 〈 0.05 ）. By DTI and DTT, compression, displacement, translocation and break were found in the ill CST. Conclusion In acute cerebral ischemic stroke, the impairment severity of CST is correlative with the change in muscle strength, and therefore, DTI and DTT have important value to its clinical management and prognosis.