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目的 研究高b值扩散成像 (DWI)诊断早期脑缺血性中风的诊断价值 ,分析假阳性与假阴性病例的磁共振表现及其规律。方法 对 2 2 5例临床诊断为脑缺血性中风的病例进行前瞻性研究 ,通过随诊或手术证实研究高b值DWI在脑缺血性中风上的诊断价值。结果 在起病的超急性期 ( <6h) ,高b值DWI对缺血性中风诊断的灵敏度为 93.5 5 % ,特异度为 10 0 %。在起病时间介于 7h～ 7d的急性病例 ,DWI的诊断灵敏度为 10 0 % ,特异度为 82 .35 %。在脑缺血病灶与其他假阳性病灶间的扩散值与各向异性变异系数之间存在显著性差异。结论 应用高b值DWI超早期诊断脑缺血时 ,基底动脉供血区存在假阴性病例是导致超早期诊断灵敏度下降的主要原因 ;而在 7h～ 7d的脑缺血急性期 ,多发性硬化与部分其他炎性疾病是造成诊断特异度下降的主要原因。对急性期的假阳性病例 ,ADC与各向异性参数计算对疾病的鉴别诊断有较大意义。
Objective To investigate the diagnostic value of high b diffusion imaging (DWI) in the diagnosis of early cerebral ischemic stroke and to analyze the MRI findings and its regularity in false positive and false negative cases. Methods A total of 225 cases of cerebral ischemic stroke were prospectively studied. The diagnostic value of high b value DWI in cerebral ischemic stroke was confirmed by follow-up or surgery. Results In the acute stage of onset (<6 h), high b value DWI had a sensitivity of 93.5 5% and a specificity of 10 0% for the diagnosis of ischemic stroke. In acute cases with onset between 7h and 7d, the diagnostic sensitivity of DWI was 100% with a specificity of 82.35%. There was a significant difference between diffusion coefficient and anisotropy coefficient of variation between cerebral ischemic lesions and other false positive lesions. Conclusions The use of high b-value DWI in the early diagnosis of cerebral ischemia, the presence of false-negative cases in the basilar artery blood supply is the main reason leading to the decrease of sensitivity of ultra-early diagnosis. In the acute phase of cerebral ischemia from 7h to 7d, multiple sclerosis and partial Other inflammatory diseases are the major causes of the decline in diagnostic specificity. False-positive cases of acute phase, ADC and anisotropic parameters calculated on the differential diagnosis of great significance.