假性蛛网膜下腔出血征的CT定量分析和鉴别诊断

CT value quantitative analysis for diagnosis and differentiation of pseudo-subarachnoid hemorrhage

目的:探讨CT平扫定量参数测量鉴别脑水肿背景下假性蛛网膜下腔出血征(P-SAH)与弥漫性蛛网膜下腔出血(D-SAH)的可行性。方法:105例研究对象分为4组,分别为P-SAH组(15例)、D-SAH组(30例)、对照组A(血红蛋白正常者30例)及对照组B(血红蛋白升高者30例),均有完整的临床和CT资料。在CT平扫图像上测量脑沟裂内血管区及其邻近脑白质的CT值,计算两者的差值(D),并进行组间比较。采用ROC曲线分析各项定量参数的诊断效能。结果:平扫CT图像上P-SAH组和D-SAH组均表现为脑沟裂内血管区与脑白质密度的差异较对照组增大、两者对比更明显。脑沟裂内血管区和邻近脑白质的CT值及D值在4组之间的差异均有统计学意义(P均<0.05)。D-SAH组脑沟裂内血管区的平均CT值为(53.26±5.50)HU,显著高于与其它3组(P<0.05);P-SAH组脑沟裂内血管区的CT值与对照组B之间的差异无统计学意义[(43.62±5.38)vs.(41.91±1.30)HU;P>0.05]。P-SAH组、D-SAH组、对照组A和对照组B的脑白质CT值分别为(26.42±2.10)、(30.11±0.77)、(29.91±1.25)和(30.37±1.31)HU,P-SAH组明显低于其它3组(P均<0.05),其它3组之间两两比较差异均无统计学意义(P均>0.05)。脑沟裂血管区与脑白质CT差值在四组之间两两比较,差异均有统计学意义(P均<0.05)。P-SAH组与对照组B之间,以差值大于13.35HU为界值来判定P-SAH,ROC曲线下面积(AUC)为0.919,敏感度84.6%,特异度90.0%;P-SAH组与D-SAH组之间,以差值小于18.15HU为界值来判定P-SAH,AUC为0.762,敏感度76.9%,特异度70.0%。结论:脑沟裂血管区和邻近脑白质的CT值及两者的差值对判断弥漫性脑水肿背景下P-SAH有较高的准确性,可资与D-SAH准确鉴别。

Objective:To explore the possibility of quantitative parameters measurement based on non-enhanced CT images for differentiating pseudo-subarachnoid hemorrhage(P-SAH)and diffuse-subarachnoid hemorrhage(D-SAH).Methods:105 subjects were included in this study,and they were in one of the 4 groups,including P-SAH group(n=15),D-SAH group(n=30),control group A(n=30,with normal hemoglobin)and control group B(n=30,with elevated hemoglobin).On non-enhanced CT images,CT values of the vascular area in sylvian fissure and the adjacent white matter were measured and the difference between them were calculated.The differences of quantitative indexes of the four groups were compared.ROC curve was used to evaluated the diagnostic efficacy of the quantitative indexes.Results:Compared with the control group,the density difference between vascular area and white matter was obviously increased on non-enhanced CT in group P-SAH and group D-SAH.There were significant differences in the CT values of vascular area in sylvian fissure and adjacent white matter,and D-value among the four groups(all P<0.05).The CT value of vascular area in group D-SAH was[(53.26±5.50)HU],which was significantly higher than that in other three groups(all P<0.05).There was no significant difference in the CT value of vascular area between group P-SAH and control group B[(43.62±5.38)vs.(41.91±1.30)HU;P>0.05].The CT value of white matter in group P-SAH(26.42±2.10)HU was significantly lower than that in group D-SAH[(30.11±0.77)HU],control group A[(29.91±1.25)HU]and control group B[(30.37±1.31)HU]with statistical difference(all P<0.05).Pair-wise comparison showed that there was statistical difference in the D-value in all groups(P<0.05).Compared the D-value of group P-SAH with control group B,when the cut-off value was 13.35HU for diagnosis of P-SAH,the area under ROC curve(AUC)was 0.919,with sensitivity of 84.6%and specialtivity of 90.0%.Compared the D-value of group P-SAH with group D-SAH,AUC was 0.762 for diagnosis of P-SAH by using 18.15HU as cut-off value,the sensitivity was 76.9%,and the specialtivity was 70.0%.Conclusion:Higher accuracy can be achieved when the CT value of white matter and D-value are used in diagnosis of P-SAH in diffuse cerebral edema,and they are helpful for differentiate from D-SAH.