多b值扩散加权成像对急性期脑梗死的诊断价值探讨

目的探讨不同b值扩散加权成像(diffusion-weighted imaging,DWI)对急性脑梗死的诊断价值。方法搜集临床拟诊为急性脑梗死患者资料387例进行多b值DWI(b=800 s/mm2、1000 s/mm2、2000 s/mm2),比较急性脑梗死区各b值间的差异。计算各b值DWI诊断急性脑梗死的敏感性、特异性、阳性预测值、阴性预测值及准确性。计算不同b值下病变部位及对侧正常组织的表观扩散系数(ADC)值,比较各b值下病变部位的ADC值间的差异及病变区与正常组织间的差异。结果 b=2000 s/mm2时DWI对急性脑梗死的诊断率明显高于b=800 s/mm2、1000 s/mm2(P<0.05)。b=800 s/mm2、1000 s/mm2时DWI诊断急性脑梗死的敏感性、特异性、阳性预测值、阴性预测值及准确性分别为94.5%、100%、100%、64.7%、95.0%与94.8%、100%、100%、65.8%、95.3%,而b=2000 s/mm2时各项统计数据均为100%。不同b值病变部位与对侧正常组织之间的ADC值差异有统计学意义(P<0.05)。结论较高b值DWI诊断急性脑梗死优于较低b值,尤其是在小病灶的显示方面更具优势。

Diagnosis Value of Several B-Value Diffusion-Weighted MR Imaging in Acute Cerebral Infarction

Objective To evaluate the diagnosis value of several b-value diffusion-weighted imaging in acute cerebral infarction.Methods 387 patients suspected with acute cerebral infarction underwent diffusion-weighted MR imaging using several b values(b=800/1000/2000 s/mm2).Using b=800,1000,2000 s/mm2,the sensitivity,specificity,positive predictive value,negative predictive value and accuracy rate were calculated.The ADC values of cerebral infarction and control under different b values were compared.Results When b = 2000 s/mm2,the accuracy rate of acute cerebral infarction was significantly higher than b= 800 s/mm2 and 1000 s/mm2(P <0.05).When b=800 s/mm2 and 1000 s/mm2,the sensitivity,specificity,positive predictive value,negative predictive value and accuracy rate of acute cerebral infarction was 94.5%,100%,100%,64.7%,95.0 % and 94.8%,100%,100%,65.8%,95.3% and when b=2000 s/mm2,the sensitivity,specificity,positive predictive value,negative predictive value and accuracy rate were all 100%.The ADC values between the lesion and contralateral normal tissue was significant difference under several b values(P <0.05).Conclusion The high b value DWI is better than the low b value DWI in the diagnosis of acute cerebral infarction,especially in small lesions.