Low-dose and standard-dose unenhanced helical computed tomography for the assessment of acute renal colic: Prospective comparative study
Low-dose and standard-dose unenhanced helical computed tomography for the assessment of acute renal colic: Prospective comparative study
复制标题
DOI：
10.1080/02841850500216004
复制
发表时间：
2005-11-01
期刊：
影响因子：
1.3
通讯作者：
Kang, WC
中科院分区：
文献类型：
--
作者：
Kim, BS;Hwang, IK;Kang, WC
目的：材料与方法：对121例疑有急性肾绞痛的患者行标准剂量（260 mAs，螺距1.5）和低剂量（50 mAs，螺距1.5）螺旋CT平扫，比较低剂量和标准剂量CT对输尿管结石的诊断价值。对这两项研究进行了前瞻性和独立的解释，包括输尿管结石的存在和位置、与结石疾病无关的异常、继发体征的识别，即肾积水和肾周搁浅以及组织边缘体征。标准剂量CT图像由一名审查员解释，低剂量CT图像由两名不知道标准剂量CT结果的审查员独立解释。将标准和低剂量CT扫描的结果与精确的McNemar检验进行比较。观察者间一致性采用kappa分析进行评估。两种不同方案产生的有效辐射剂量通过市售软件计算，其中给出了蒙特-卡罗体模模型。标准剂量CT检测输尿管结石的敏感性、特异性和准确性分别为99%、93%和98%，而两位评价者低剂量CT的敏感性分别为93%和95%，特异性86%，准确性92%和94%。我们发现标准剂量和低剂量CT诊断输尿管结石的敏感性和特异性无显著差异（均P>0.05）。然而，对于两位评审员，低剂量CT检测19个直径小于或等于2 mm结石的灵敏度分别为79%和68%。低剂量CT在显示肾积水和组织边缘征方面与标准剂量CT相当。肾周搁浅在低剂量CT上不太清楚。低剂量CT与标准剂量CT在诊断其他疾病方面具有相同的诊断性能。两名低剂量CT审查者在输尿管结石和替代疾病的诊断、继发体征的识别和组织边缘征方面的观察者间一致性较高，Kappa值范围为0.769至0.968。在标准剂量CT扫描中，计算的平均有效辐射剂量为男性7.30 mSv，女性10.00 mSv。在低剂量CT扫描，计算出的平均有效辐射剂量为1.40 mSv的男性和1.97 mSv的females.Conclusion：与标准扫描使用260 mAs相比，低剂量未增强螺旋CT使用减少管电流50 mAs的结果在一个伴随的辐射剂量减少了81%。尽管低剂量CT对小于或等于2分钟的小结石的显示能力有限，但在输尿管结石和替代疾病的诊断方面，低剂量CT仍与标准剂量CT相当。
Purpose: To compare the efficacy of low-dose and standard-dose computed tomography (CT) for the diagnosis of ureteral stones.Material and Methods: Unenhanced helical CT was performed with both a standard dose (260 mAs, pitch 1.5) and a low dose (50 mAs, pitch 1.5) in 121 patients suspected of having acute renal colic. The two studies were prospectively and independently interpreted for the presence and location of ureteral stones, abnormalities unrelated to stone disease, identification of secondary signs, i.e. hydronephrosis and perinephric stranding, and tissue rim sign. The standard-dose CT images were interpreted by one reviewer and the low-dose CT images independently by two reviewers unaware of the standard-dose CT findings. The findings of the standard and low-dose CT scans were compared with the exact McNemar test. Interobserver agreements were assessed with kappa analysis. The effective radiation doses resulting from two different protocols were calculated by means of commercially available software to which the Monte-Carlo phantom model was given.Results: The sensitivity, specificity, and accuracy of standard-dose CT for detecting ureteral stones were 99%, 93%, and 98%, respectively, whereas for the two reviewers the sensitivity of low-dose CT was 93% and 95%, specificity 86%, and accuracy 92% and 94%. We found no significant differences between standard-dose and low-dose CT in the sensitivity and specificity for diagnosing ureter stones (P>0.05 for both). However, the sensitivity of low-dose CT for detection of 19 stones less than or equal to 2 mm in diameter was 79% and 68%, respectively, for the two reviewers. Low-dose CT was comparable to standard-dose CT in visualizing hydronephrosis and the tissue rim sign. Perinephric stranding was far less clear on low-dose CT. Low-dose CT had the same diagnostic performance as standard-dose CT in diagnosing alternative diseases. Interobserver agreement between the two low-dose CT reviewers in the diagnosis of ureter stones and alternative diseases, the identification of secondary signs, and tissue rim sign were high, with kappa values ranging from 0.769 to 0.968. On standard-dose CT scans, the calculated mean effective radiation dose was 7.30 mSv for males and 10.00 mSv for females. On low-dose CT scans, the calculated mean effective radiation dose was 1.40 mSv for males and 1.97 mSv for females.Conclusion: Compared with standard scans using 260 mAs, low-dose unenhanced helical CT using a reduced tube current of 50 mAs results in a concomitant decrease in the radiation dose of 81%. Although low-dose CT was limited in its ability to depict small-sized calculi less than or equal to 2 min, it is still comparable to standard-dose CT for the diagnosis of ureter stones and alternative disease.