Department of Urology, Loma Linda University School of Medicine, 11234 Anderson St, Room A560, Loma Linda, CA 92354, USA.
Radiology. 2010 Apr;255(1):100-7. doi: 10.1148/radiol.09090583.
To determine the effect of reduced radiation (tube charge, measured as milliamperes per second) protocols on the sensitivity and specificity of multidetector computed tomography (CT) in the detection of renal calculi.
This Health Insurance Portability and Accountability Act-compliant human cadaveric study was approved by the Department of Anatomic Pathology with strict adherence to the university policy for handling donor specimens. Three to five renal stones (range, 2.0-4.0 mm) were randomly placed in 14 human cadaveric kidneys and scanned with a 16-detector CT scanner at 100, 60, and 30 mAs while maintaining other imaging parameters as constant. Following acquisition, images were reviewed independently by two radiologists who were blinded to the location and presence of renal calculi. Interobserver agreement was measured with kappa statistics. The McNemar test was used to compare the sensitivity and specificity between different radiation settings for each reader.
Specificity for both readers ranged from 105 (0.95; 95% confidence interval [CI]: 0.90, 0.99) to 109 (0.99; 95% CI: 0.95, 1.0) of 110 without significant differences between 30 and 60 mAs to the standard 100 mAs (P = .500 to >.999). Sensitivity ranged from 42 (0.74; 95% CI: 0.60, 0.84) to 48 (0.84; 95% CI: 0.72, 0.93) of 57, also without significant differences (P = .070 to >.999). When renal calculi detection rates were analyzed by size, 3.0-4.0-mm stones were detected well at all tube charge settings, ranging from 86%-90% (n = 21 for 3.0-mm stones) to 95%-100% (n = 19 for 4.0-mm stones). However, 2.0-mm stones were poorly detected at all tube charge settings (29%-59%; 5-10 of 17). Overall interobserver agreement for stone detection was excellent, with kappa = 0.862.
Decreasing the tube charge from 100 to 30 mAs resulted in similar detection of renal stones while reducing patient radiation exposure by as much as 70%. Multidetector CT scanning parameters should be tailored to minimize radiation exposure to the patients while helping detect clinically significant renal stones.
确定降低辐射（以毫安秒计的管电流）方案对多排 CT 检测肾结石的敏感性和特异性的影响。
本研究符合《健康保险携带和责任法案》的要求，得到了解剖病理学系的批准，并严格遵守了大学处理供体标本的政策。将 3 到 5 颗肾结石（大小 2.0-4.0mm）随机放置在 14 个人体尸体肾脏中，并在管电流分别为 100、60 和 30 mAs 时使用 16 排 CT 扫描仪进行扫描，同时保持其他成像参数不变。采集后，由两位放射科医生独立对图像进行审查，他们对肾结石的位置和存在情况并不知情。通过 Kappa 统计测量观察者间的一致性。使用 McNemar 检验比较不同辐射设置下每位读者的敏感性和特异性。
两位读者的特异性均为 110 例中 105 例（0.95；95%置信区间：0.90，0.99）至 109 例（0.99；95%置信区间：0.95，1.0），30 mAs 和 60 mAs 与标准 100 mAs 之间没有显著差异（P =.500 至>.999）。敏感性范围为 57 例中 42 例（0.74；95%置信区间：0.60，0.84）至 48 例（0.84；95%置信区间：0.72，0.93），也没有显著差异（P =.070 至>.999）。当按结石大小分析结石检出率时，3.0-4.0mm 结石在所有管电流设置下均能很好地检出，范围为 86%-90%（3.0mm 结石 21 例）至 95%-100%（4.0mm 结石 19 例）。然而，2.0mm 结石在所有管电流设置下均检出不佳（29%-59%；17 例中 5-10 例）。总体而言，结石检测的观察者间一致性极好，Kappa = 0.862。
将管电流从 100 降低至 30 mAs 可使肾结石的检出率相似，同时将患者的辐射暴露量降低 70%。应调整多排 CT 扫描参数，以尽量减少患者的辐射暴露，同时帮助检出具有临床意义的肾结石。
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