From the Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany (S.A., O.N., M.M., M.W., A.E.O.); Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany (S.A., K.N., A.E.O.); Department of Neuroradiology, University Hospital Mainz, Mainz, Germany (M.A.B., C.B.); Institute for Clinical Radiology, Ludwig-Maximilian-University Hospital Munich, Munich, Germany (K.M.T.); Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, South Korea (J.H.K.); Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea (J.H.K.); and Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon, South Korea (J.H.K.).
Radiology. 2018 May;287(2):643-650. doi: 10.1148/radiol.2017162707. Epub 2018 Jan 8.
Purpose To evaluate diagnostic accuracy of low-dose volume perfusion (VP) computed tomography (CT) compared with original VP CT regarding the detection of cerebral perfusion impairment after aneurysmal subarachnoid hemorrhage. Materials and Methods In this retrospective study, 85 patients (mean age, 59.6 years; 62 women) with aneurysmal subarachnoid hemorrhage and who were suspected of having cerebral vasospasm at unenhanced CT and VP CT (tube voltage, 80 kVp; tube current-time product, 180 mAs) were included, 37 of whom underwent digital subtraction angiography (DSA) within 6 hours. Low-dose VP CT data sets at tube current-time product of 72 mAs were retrospectively generated by validated realistic simulation. Perfusion maps were generated from both data sets and reviewed by two neuroradiologists for overall image quality, diagnostic confidence and presence and/or severity of perfusion impairment indicating vasospasm. An interventional neuroradiologist evaluated 16 vascular segments at DSA. Diagnostic accuracy of low-dose VP CT was calculated with original VP CT as reference standard. Agreement between findings of both data sets was assessed by using weighted Cohen κ and findings were correlated with DSA by using Spearman correlation. After quantitative volumetric analysis, lesion volumes were compared on both VP CT data sets. Results Low-dose VP CT yielded good ratings of image quality and diagnostic confidence and classified all patients correctly with high diagnostic accuracy (sensitivity, 99.0%; specificity, 99.5%) without significant differences regarding presence and/or severity of perfusion impairment between original and low-dose data sets (Z = -0.447; P = .655). Findings of both data sets correlated significantly with DSA (original, r = 0.671; low dose, r = 0.667). Lesion volume was comparable for both data sets (relative difference, 5.9% ± 5.1 [range, 0.2%-25.0%; median, 4.0%]) with strong correlation (r = 0.955). Conclusion The results suggest that radiation dose reduction to 40% of original dose levels (tube current-time product, 72 mAs) may be performed in VP CT imaging of patients with aneurysmal subarachnoid hemorrhage without compromising the diagnostic accuracy regarding detection of cerebral perfusion impairment indicating vasospasm. RSNA, 2018 Online supplemental material is available for this article.
目的 评估低剂量容积灌注（VP）计算机断层扫描（CT）在诊断脑动脉瘤性蛛网膜下腔出血后脑灌注损伤方面的诊断准确性，与原始 VP CT 进行比较。
材料与方法 本回顾性研究纳入了 85 例（平均年龄 59.6 岁；62 例女性）疑似脑动静脉畸形患者，这些患者在非增强 CT 和 VP CT（管电压 80 kVp；管电流-时间乘积 180 mAs）上发现了蛛网膜下腔出血，并接受了数字减影血管造影（DSA）检查。通过验证的真实模拟，从原始管电流-时间乘积 72 mAs 的低剂量 VP CT 数据集中生成了低剂量 VP CT 数据。从两个数据集生成灌注图，并由两位神经放射科医生对整体图像质量、诊断信心以及存在和/或严重程度的灌注损伤（提示血管痉挛）进行评估。一位介入神经放射科医生在 DSA 上评估了 16 个血管节段。以原始 VP CT 为参考标准，计算低剂量 VP CT 的诊断准确性。使用加权 Cohen κ 评估两个数据集的发现之间的一致性，并使用 Spearman 相关性评估与 DSA 的相关性。在进行定量容积分析后，比较了两个 VP CT 数据集上的病变体积。
结果 低剂量 VP CT 获得了良好的图像质量和诊断信心评分，并以高诊断准确性正确分类了所有患者（敏感度为 99.0%，特异度为 99.5%），原始和低剂量数据集之间在灌注损伤的存在和/或严重程度方面没有显著差异（Z = -0.447；P =.655）。两个数据集的发现与 DSA 均显著相关（原始数据，r = 0.671；低剂量数据，r = 0.667）。两个数据集的病变体积相当（相对差异为 5.9%±5.1[范围，0.2%-25.0%；中位数，4.0%]），具有很强的相关性（r = 0.955）。
结论 结果表明，在不影响检测提示血管痉挛的脑灌注损伤的诊断准确性的情况下，可将辐射剂量降低至原始剂量水平的 40%（管电流-时间乘积，72 mAs），对脑动脉瘤性蛛网膜下腔出血患者进行 VP CT 成像。RSNA，2018 在线补充材料可为此文章提供参考。
