MSCT增强扫描造影剂注射速度对小肝癌诊断的影响

Effect of Injection Rate of Contrast Material on MSCT of Small Hepatocellular Carcinoma: ROC Analysis

目的:评价不同速度注射造影剂进行多层螺旋CT(MSCT)增强扫描对小肝癌(SHCC)诊断效果的影响。方法:使用64层螺旋CT,分别用3ml/s和5ml/s速度团注造影剂对拟诊为SHCC的两组患者进行增强扫描,每组30名,其中3ml/s组35个病灶,5ml/s组41个病灶。采用BOLUS track ing团注造影剂跟踪软件确定动脉期扫描的开始时间。利用受试者工作特征(ROC)分析比较不同注射速度所获动脉期图像的诊断效果。结果:3ml/s组ROC曲线下面积(Az值)和灵敏度分别为0.93±0.01和28/35(80%),5ml/s组则分别为0.91±0.01和36/41(88%),两组间无显著性差异。但3ml/s组的特异度和阳性预测值分别为236/250(95%)和28/42(67%),高于5ml/s组[227/265(86%)和36/73(49%)],差异有统计学意义(P<0.05),表明以5ml/s速度注射造影剂进行MSCT增强扫描所获得的动脉期图像对于有肝硬化背景的高血供SHCC的诊断假阳性率高于3ml/s。结论:并存肝硬化的高血供SHCC患者进行MSCT检查时,采用中等速度(3ml/s)注射造影剂增强扫描动脉期假阳性结果较少,诊断效果优于较高速度(5ml/s)注射。

Objective： To assess the effect of injection rates of contrast material in hepatic arterial phase multi- slice CT （MSCT） for the detection of small hepatocellular carcinomas （SHCC）. Methods：The injection rates 3ml/s and 5ml/s of same contrast material were used in imaging examinations of patients with the suspected diagnosis of hepatoceUular carcinoma. Each group consisted of 30 patients by chance. The group that received injections at 3ml/s had 35 SHCC lesions, and the 5ml/s group had 41 lesions. Receiver operating characteristic analysis was used to assess diagnostic performance with the two injection rates of contrast material. Results：The area under the curve （Az value） and sensitivity values for the 3ml/s group were 0.93 ± 0.01 and 28/35 （80%） and for the 5ml/s group were 0.91 ± 0.01 and 36/41 （88%）. There were no statistically significant differences between the two groups. However, the specificity and positive predictive values at 3m//s （236/250 [ 95% ] and 28/42 [ 67% ] ） were signiflcandy higher than those at 5 ml/ s （227/265 [ 86% ] and 36/73 [49% ] ） （P 〈 0.05 ）. These results suggest there were more false-positive findings of contrast-en- hanced lesions in cirrhotic livers on hepatic arterial phase images obtained after injection of contrast material at 5ml/s than on images obtained after injection at 3ml/s. Conclusion：In the detection of hypervascular SHCC in cirrhotic liver,the risk of false -positive findings of lesions on hepatic arterial phase images is lower and diagnostic performance is better with the medium rate （3ml/s） than with the higher injection rate （5ml/s）.