The Department of Radiology and Centre for Imaging Science, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Br J Radiol. 2012 Jun;85(1014):e176-81. doi: 10.1259/bjr/19566194. Epub 2011 Sep 6.
The aim of our study was to determine if virtual unenhanced CT (VUCT) is equivalent to unenhanced CT (UCT) for detecting urinary stones.
Our institutional review board approved this retrospective study, which was compliant with the Health Insurance Portability and Accountability Act. A total of 80 stones were detected in 32 patients among 146 consecutive patients undergoing dual-energy CT urography. The number and size of stones were recorded on nephrographic VUCT (NVUCT) and excretory VUCT (EVUCT) images, respectively. UCT was a reference of standard for the number and size of stones. Image quality of VUCT was qualitatively assessed using a five-point scale. Repeated-measures analysis of variance with post-test was used for statistical analysis.
62 stones in 29 patients were detected on NVUCT and 59 stones in 27 patients were detected on EVUCT. The size of stones detected on NVUCT or EVUCT was significantly smaller compared with stones on UCT (p<0.05). The size of stones detected on UCT, NVUCT and EVUCT ranged from 1.4 to 19.2 mm (mean, 4.6 mm), 0 to 19.2 mm (mean, 3.6 mm) and 0 to 18.7 mm (mean, 3.6 mm), respectively. 18 stones were missed on NVUCT and 21 were missed on EVUCT. The sizes ranged from 1.4 to 3.2 mm (mean, 2.1 mm) and 1.4 to 3.2 mm (mean, 2.2 mm) on UCT, respectively. VUCT was inferior to UCT regarding image quality (p<0.05).
VUCT missed a significant number of small stones probably owing to poor image quality compared with UCT. Subsequently, VUCT cannot replace UCT for detecting urinary stones.
本研究旨在确定虚拟非增强 CT（VUCT）是否等同于非增强 CT（UCT）用于检测尿路结石。
我们的机构审查委员会批准了这项回顾性研究，该研究符合《健康保险流通与责任法案》。在 146 例连续行双能 CT 尿路造影的患者中，32 例患者共检出 80 个结石。分别记录肾实质 VUCT（NVUCT）和排泄期 VUCT（EVUCT）图像上结石的数量和大小。UCT 是结石数量和大小的参考标准。VUCT 的图像质量采用五分制进行定性评估。采用重复测量方差分析和事后检验进行统计学分析。
29 例患者的 NVUCT 检出 62 个结石，27 例患者的 EVUCT 检出 59 个结石。NVUCT 或 EVUCT 检出的结石大小明显小于 UCT （p<0.05）。UCT、NVUCT 和 EVUCT 检出的结石大小范围为 1.4 至 19.2mm（平均 4.6mm）、0 至 19.2mm（平均 3.6mm）和 0 至 18.7mm（平均 3.6mm）。NVUCT 漏诊 18 个结石，EVUCT 漏诊 21 个结石。这些结石的大小范围为 UCT 上的 1.4 至 3.2mm（平均 2.1mm）和 1.4 至 3.2mm（平均 2.2mm）。VUCT 的图像质量明显劣于 UCT（p<0.05）。
与 UCT 相比，VUCT 由于图像质量较差，可能会漏诊大量小结石。因此，VUCT 不能替代 UCT 用于检测尿路结石。
