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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。
Objective To investigate the diagnostic value of different b-value diffusion-weighted imaging (DWI) in acute cerebral infarction. Methods Thirty-eight patients with suspected acute cerebral infarction who were clinically diagnosed as having acute cerebral infarction were enrolled in this study. The b-value DWI (b = 800 s / mm 2, 1000 s / mm 2, 2000 s / mm 2) The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of each b-value DWI in the diagnosis of acute cerebral infarction were calculated. Apparent diffusion coefficient (ADC) value of lesion and contralateral normal tissue at different b values were calculated. The difference of ADC value between lesions at different b values and the difference between lesions and normal tissues were compared. Results The diagnostic rate of DWI in patients with acute cerebral infarction at b = 2000 s / mm2 was significantly higher than that at b = 800 s / mm2 and 1000 s / mm2 (P <0.05). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of DWI in the diagnosis of acute cerebral infarction with b = 800 s / mm2 and 1000 s / mm2 were 94.5%, 100%, 100%, 64.7% and 95.0% And 94.8%, 100%, 100%, 65.8% and 95.3% respectively, while the statistics for b = 2000 s / mm2 are all 100%. There was significant difference in ADC value between different b-value lesion and contralateral normal tissue (P <0.05). Conclusions Higher b-value DWI is superior to lower b-value in the diagnosis of acute cerebral infarction, especially in the display of small lesions.