Department of Urology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792-3252, USA.
J Urol. 2011 Dec;186(6):2275-9. doi: 10.1016/j.juro.2011.07.091. Epub 2011 Oct 20.
We compared the reproducibility of automated volume and manual linear measurements using same study supine and prone, low dose, noncontrast computerized tomography series.
The patient cohort comprised 50 consecutive adults with a mean age of 56.4 years in whom renal calculi were identified during computerized tomography colonography screening. The largest stone per patient was assessed with the supine and prone computerized tomography series serving as mutual controls. Automated stone volume was derived using a commercially available coronary artery calcium scoring tool. Supine-prone reproducibility for automated volume was compared with intra-observer supine-prone manual linear measurement. Interobserver variability was also assessed for manual linear measurements of the same supine or prone series.
Mean ± SD linear size and volume of the 50 index calculi was 4.5 ± 2.7 mm (range 1.8 to 16) and 141.7 ± 456.1 mm(3), respectively. The mean supine-prone error for automated stone volume was 16.3% compared with an average 11.7% 1-dimensional intra-observer error for manual axial measurement. Only 2 of 15 cases with a volume error of greater than 20% were 5 mm or greater in linear size. The average interobserver linear error for the same computerized tomography series was 26.3% but automated volume measurement of the same series did not vary.
Automated noncontrast computerized tomography renal stone volume is more reproducible than manual linear size measurement and it avoids the often large interobserver variability seen with manual assessment. Since small linear differences correspond to much larger volume changes, greater absolute volume errors are acceptable. Automated volume measurement may be an improved clinical parameter to use for following the renal stone burden.
我们比较了使用相同的仰卧位和俯卧位、低剂量、非对比计算机断层扫描系列的自动体积和手动线性测量的可重复性。
患者队列包括 50 名连续的成年人，平均年龄为 56.4 岁，在计算机断层结肠造影筛查中发现肾结石。每位患者最大的结石用仰卧位和俯卧位计算机断层扫描系列作为相互对照进行评估。使用商业上可用的冠状动脉钙评分工具得出自动结石体积。比较仰卧位-俯卧位自动体积的重复性与仰卧位-俯卧位手动线性测量的观察者内重复性。还评估了同一仰卧位或俯卧位系列的手动线性测量的观察者间变异性。
50 个指数结石的平均±SD 线性尺寸和体积分别为 4.5±2.7mm（范围 1.8 至 16）和 141.7±456.1mm(3)。与手动轴向测量的平均 11.7%一维观察者内误差相比，自动结石体积的仰卧位-俯卧位误差平均为 16.3%。只有 2 例体积误差大于 20%的结石线性尺寸为 5mm 或更大。同一计算机断层扫描系列的平均观察者间线性误差为 26.3%，但同一系列的自动体积测量没有变化。
与手动线性尺寸测量相比，自动非对比计算机断层扫描肾结石体积更具可重复性，并且避免了手动评估中常见的观察者间较大变异性。由于线性差异较小对应于体积变化较大，因此可以接受更大的绝对体积误差。自动体积测量可能是一种改进的临床参数，用于跟踪肾结石负担。
