Department of Radiological Technology, Tsuchiya General Hospital, Nakajima-cho 3-30, Naka-ku, Hiroshima 730-8655, Japan; Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan.
Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
Acad Radiol. 2018 Oct;25(10):1298-1304. doi: 10.1016/j.acra.2018.01.019. Epub 2018 Mar 26.
We compared the radiation dose and diagnostic accuracy on 120- and 100-kVp coronary computed tomography angiography (CCTA) scans whose contrast-to-noise ratio (CNR) was the same.
We studied 1311 coronary artery segments from 100 patients. For 120-kVp scans, the targeted image level was set at 25 Hounsfield units (HU). For 100-kVp scans, the targeted noise level was set at 30 HU to obtain the same CNR as at 120 kVp. We compared the CNR and the radiation dose on scans acquired at 120 and 100 kVp. Invasive coronary angiography (ICA) images were evaluated by an interventional coronary angiography specialist, and CCTA images were evaluated by a radiologist. Coronary artery disease was defined as a luminal narrowing ≧50% for ICA and CCTA. With ICA considered the gold standard, the diagnostic accuracy (sensitivity, specificity, positive predictive value, and negative predictive value) was analyzed on both 120- and 100-kVp CCTA images. We also compared the diagnostic accuracy for area under the receiver operating characteristic curve of the ICA and CCTA performed at 120 and 100 kVp. Two blinded observers visually evaluated the septal branch.
The mean dose-length product was 48% lower at 100 kVp than at 120 kVp (P < .01). Under the 120-kVp CCTA protocol, the area under the curve, 95% confidence interval, sensitivity, specificity, positive predictive value, and negative predictive value were 0.94%, 0.91%-0.96%, 94.0%, 93.0%, 82.3%, and 98.1%, respectively; at 100 kVp these values were 0.94%, 0.92%-0.97%, 96.1%, 92.0%, 85.2%, and 98.0%, respectively. Area under the receiver operating characteristic curve analysis revealed no significant difference in diagnostic accuracy between the two protocols (P = .87).
At the same CNR, the 100-kVp CCTA protocol may help to reduce the radiation dose by approximately 50% compared to the 120-kVp protocol without degradation of diagnostic accuracy.
本研究旨在对比两种管电压（120kVp 和 100kVp）下冠状动脉 CT 血管造影（CCTA）的辐射剂量和诊断准确性，这些扫描的对比噪声比（CNR）相同。
我们对 100 名患者的 1311 个冠状动脉节段进行了研究。对于 120kVp 扫描，将目标图像水平设置为 25 亨氏单位（HU）。对于 100kVp 扫描，将目标噪声水平设置为 30HU，以获得与 120kVp 相同的 CNR。我们比较了在 120kVp 和 100kVp 下采集的扫描的 CNR 和辐射剂量。由介入冠状动脉造影专家评估冠状动脉造影（ICA）图像，由放射科医生评估 CCTA 图像。冠状动脉疾病定义为 ICA 和 CCTA 显示管腔狭窄≧50%。以 ICA 为金标准，分析了 120kVp 和 100kVp CCTA 图像的诊断准确性（敏感性、特异性、阳性预测值和阴性预测值）。我们还比较了在 120kVp 和 100kVp 下进行的 ICA 和 CCTA 的受试者工作特征曲线下面积的诊断准确性。两位盲法观察者对间隔支进行了视觉评估。
与 120kVp 相比，100kVp 时剂量长度乘积降低了 48%（P<.01）。在 120kVp CCTA 方案下，曲线下面积、95%置信区间、敏感性、特异性、阳性预测值和阴性预测值分别为 0.94%、0.91%-0.96%、94.0%、93.0%、82.3%和 98.1%；在 100kVp 时这些值分别为 0.94%、0.92%-0.97%、96.1%、92.0%、85.2%和 98.0%。受试者工作特征曲线分析显示两种方案的诊断准确性无显著差异（P=.87）。
在相同 CNR 下，与 120kVp 方案相比，100kVp CCTA 方案可将辐射剂量降低约 50%，而不会降低诊断准确性。
