联合弥散加权成像与弥散张量成像对缺血性小卒中诊断及预后评估的价值

Combined application of diffusion weighted imaging and diffusion tensor imaging techniques for diagnostic and prognostic assessment on minor ischemic stroke

目的探讨联合应用弥散加权成像(DWI)与弥散张量成像(DTI)技术在诊断、评估缺血性小卒中的价值。方法选择41例氯吡格雷用于急性非致残性脑血管事件高危人群的疗效研究课题入组的缺血性小卒中患者。28例患者行MRI基线扫描(发病后3d内)及随访MRI复查,13例仅做基线扫描。其中1例因并发出血终止研究,其余40例患者均在发病后3个月接受临床随访。扫描序列包括常规MRI、DWI及DTI序列。重建表观弥散系数(ADC)图、部分各向异性(FA)图、FA彩色编码图、弥散张量纤维束成像(DTT)图,分别测量患侧及健侧相应部位ADC值、FA值。对预后的评价采用美国国立卫生研究院卒中评分。结果 41例缺血性小卒中患者基线扫描DWI与DTI均发现梗死病灶,其中5例为超急性脑梗死,36例为急性脑梗死。41例患者基线DWI序列上患侧呈高信号,ADC值下降,患侧ADC值与健侧比较,差异具有统计学意义(P<0.01);36例急性脑梗死患者患侧FA值明显低于健侧(P<0.01),而5例超急性脑梗死患者FA值无特异性改变。28例患者复查时所有患侧ADC值较基线进一步升高,FA值下降(P均<0.01)。DTT图显示的19例皮质脊髓束受累和6例胼胝体受损患者预后较差,其余患者预后较好。结论 DWI技术能早期发现缺血性小卒中病灶、帮助定位诊断,而DTI技术能更好地反映患者白质纤维束情况、指导康复治疗。联合应用两者有助于缺血性小卒中的诊断及预后评估。

Objective To investigate the value of combined application of diffusion weighted imaging （DW1） and diffusion tensor imaging （DT1） techniques for diagnostic and prog nostic assessment on minor ischemic stroke. Methods Forty-one cases with minor ischaemic stroke from clopidogrel in high risk patients with acute non-disabling cerebrovascular task were enrolled in this study. Twenty-eight cases received MRI baseline scan （within 3 d after symptom onset） and follow-up MRI examination, while the rest 13 cases only baseline scan. Except for 1 cases complicated with hemorrhage got the study terminated, the rest 40 cases were all clinically followed up for 3 months. Scanning sequence included conventional magnetic resonance imaging, DWI, and DTI. The maps of apparent diffusion coefficient （ADC）, fractional anisotropy （FA）, FA encoded color, and diffusion tensor tractography （DTI＇） were then reconstructed, and the values of ADC and FA on stroke lesions and corresponding contralateral sides were measured and compared. The national institutes of health stroke scale was used to assess prognosis. Results Of all the 41 cases, 5 with hyperacute cerebral infarction and 36 acute cerebral infarction. Theinfarcted regions could be differentiated from healthy tissue on both DWI and DTI, The lesions in the 41 cases were high signal intensity on DWI, and the ADC values decreased as compared with the contralateral sides （P 〈 0.01）. The FA values of the lesions in the 36 cases with acute cerebral infarction were lower than the contralateral sides （P 〈 0.01）, whereas in the 5 with hyperacute cerebral infarction showed no specific changes. The follow-up MRI results on the lesions of the 28 cases demonstrated that ADC values increased and FA decreased as compared with the baseline （all P〈 0.01）. Nineteen cases with corticospinal tract involvement in and 6 corpus callosum deficit showed by Dq＇T maps encountered with poor recovery, while the rest with better improvement. Conclusions DWI can detect the small acute lesions of minor ischaemic stroke on the early stage and offer parameters to assess location, while DTI can better reflect white matter fiber tracts and guide rehabilitation. Combined application of DWI and DTI can be useful to diagnose and estimate the prognosis in patients with minor ischaemic stroke.