不同浓度对比剂MSCT增强诊断小肠出血的对比实验

A comparative experimental study of MSCT with different concentrations of contrast agents in diagnosing small bowel hemorrhage

目的:比较4种不同浓度对比剂MSCT增强显示小肠单个出血点持续出血的敏感性。方法:将4种不同浓度对比剂(300、350、370和400mg I/ml)分别配制成3%、4%、5%(其中400mgI/ml还配制成2.5%),模拟MSCT增强对比剂以3、4和5ml/s流率注射时(对于2.5%则为2.5ml/s注射流率)单位时间内动脉血液中相应对比剂的理论浓度,采用微泵装置分别模拟0.05、0.1、0.2、0.3、0.4和0.5ml/min的出血量通过3F微导管注入透X线容器制成的模型内。64层螺旋CT机分别在注射对比剂后3s、30s时扫描,模拟MSCT增强时的动、静脉期成像,比较4种不同浓度对比剂对模拟出血检出的敏感性。结果:400mg I/ml对比剂显示模拟少量小肠出血最敏感,可显示模拟0.05ml/min以上出血;随着对比剂浓度的增加,4种对比剂对模拟出血检出率增加,400mg I/ml对模拟出血检出率高于300mg I/ml且有统计学差异(P<0.05);400mg I/ml对比剂在注射流率为2.5ml/s时与300mg I/ml对比剂在注射流率为3ml/s时对模拟出血检出率无统计学差异。结论:MSCT增强高浓度对比剂有利于小肠出血的显示;高浓度对比剂适当降低注射流率诊断小肠出血具有可行性。

To compare the sensitivities of 4 different concentrations of contrast agents in detecting a single point of persistent small bowel hemorrhage using 64-MSCT. Methods： Four kinds of contrast medium（300mg I/ml, 350rag I/ml,370mg I/nil and 400rag I/ml） were diluted into 3%, 4%and 5%, respectively. Flow rates of 3ml/s, 4ml/s, 5ml/s （400mg I/ml was also diluted into 2.5 ~） were used to simulate contrast medium＇s theoretical concentrations. The contrast agents were injected into a radiolucent cylindric model filled with water through a 3F microcatheter at different rate of 0.05ml/min,0. lml/min,0.2ml/min,0.3ml/min,0.4 ml/min and 0.5ml/min which imitated the status of bleeding bowel. The experimental model was scanned by 64-MSCT at 3s and 30s after injection of the agents. The sensitivities of 4 kinds of contrast agents in detecting small bowel hemorrhage were compared. Results： The eonccentration of 400rag I/ml was the most sensitive to detect a small amount of small bowel hemorrhage over 0.05ml/min. With the increase of the concentration of contrast medium,the total detection rate of simulated hemorrhage also increased. The total detection rate of simulated howel hemorrhage of 400rag I/ml was higher than that of 300rag I/ml（P〈0.05）. The total detection rates for simulated bowel hemorrhage between using contrast agents of 400mg I/ml with the flow rate of 2.5ml/s and 300mg I/ml with the flow rate of 3ml/s were not statistically significant. Conclusion：Contrast medium of high concentration is conducive to detec- ting small amount of hemorrhage like small bowel bleeding by using MSCT. It＇s feasible to use lower injection rate and high er concentration of contrast medium for diagnosis of small bowel bleeding.