【摘要】 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。更多还原

【Abstract】 Objective To study the diagnostic value of difusion weighted imaging in brain ischemic stroke and to summarize the MR appearances and characteristics of the false negative and false positive cases.Methods 225 cases which were highly suspected of brain ischemic stroke were studied prospectively.The final diagnosis of the cases were verified by following up examination or pathology.The diagnostic value were calculated.Results The sensitivity and specificity for the diagnosis of ischemic stroke were 93.55% and 100% at superacute stage(<6 h).During the time range of 7 h～7 d,the sensitivity and the specificity were 100% and 82.35% respectively.ADC value and CV between them were statisically different from that of the false positive cases.Conclusion The false negative cases of the ischemic lesions in the basilar artery supply region accounted for the lower specificity of DWI at superacute stage.While the multiple sclerosis and cerebritis lesions are the reason for lower sensitivity at acute stage.ADC and anisotropy parameter images are valuable for the differential diagnosis of the confusing cases.更多还原