低放射剂量螺旋CT平扫诊断肾及输尿管结石

The diagnosis of nephrolithiasis and ureterolithiasis using low dose unenhanced 16 detector helical CT

目的评价64层螺旋CT低剂量平扫对肾及输尿管结石的诊断价值。方法收集临床疑为肾及输尿管结石患者45例,全部患者行常规标准剂量(120KV,160mAs)和低剂量扫描(120KV,80mAs),扫描范围均保持不变。采用双盲随机法,由2名副主任医师诊断结石的有无、大小、位置、数目及结石的继发梗阻征象及其他临床相关表现,采用配对t检验和秩和检验比较。结果在标准剂量扫描中,34例患者发现结石81个;其中<0.5cm的结石20个,0.5～1.0cm的结石29个,>1.0cm的结石32个;在低剂量扫描中,33例患者发现结石76个,其中<0.5cm的结石17个,0.5cm～1.0cm的结石28个,>1.0cm的结石32个;以标准剂量结果为标准,低剂量扫描的准确率为:<0.5cm结石的准确率为85%,0.5～1.0cm结石的准确率为93.1%,>1.0cm结石的准确率为100%。与标准剂量扫描比较,低剂量扫描放射剂量下降50%,两者差异有统计学意义(P<0.05)。结论对于体质量<90kg的患者,将球管电流降为80mAs进行螺旋CT平扫可减低患者辐射剂量并保持很高准确性。

Objective To determine the accuracy of low dose unenhanced 64 detector helical computed tomography(CT) in the diagnosis of nephrolithiasis and ureterolithiasis. Methods 45 patients with suspected nephrolithiasis and ureterolithiasis were colected, Followed by standard dose helical CT scalls with 120kv,160mAs,bv low dose scan was carried out with the tube current reduced to 80mAs,All other technical Darameters and anatomic coverage remained constant. Using double - blind randomly,the location,size and number of calculi,the secondary signs of obstruetion,and the radiation dose were observed by two senior experienced physicians. Re- sults With the standard dose scan,81 stones were found in 34 patients,In them,20 stones were less than 0. 5cm in diameter,29 stones were more than 0. 5cm and less than 1. 0cm. 32 stones ere more than 1. 0cm. With the low dose scan,76 stones were found in 33 patients,In them,17 stones were 1ess than 0. 5cm in diameter,28 stones were more than 0. 5cm and less than 1. 0cm,32 stones were more than 1. 0cm. Compared with the standard dose scan,The accuracy rates of detecting nephrolithiasis and ureterolithiasis on the low dose scan was 85% 、93. 1% and 100% for less than 0. 5cm. more than 0. 5cm and less than 1. 0cm and more than 1. 0cm in diameter,and the radiation dose was decreased by 50% in 4He low dose scan,with signifieant differenc% ( P < 0. 05) . Conclusion Hibh accuracy for 4ha detection of nephrolithiasis and uretdrolithiasi3 is obtained and the radiation dose is significantly decreased by using unenhanced 16 detector helical CT performed at a reduced tube current of 80 mAs for the patients less than 90 kg.