分次稀释替代注射在儿童低剂量心脏CT血管成像中的应用研究

目的探讨分次稀释替代注射技术在儿童低剂量心脏血管CT成像(CCTA)中的应用价值。方法经医院伦理委员会审核同意,126例先天性心脏病患儿在术前进行了CCTA扫描,全部病例来源于广州市儿童医院2008年5月至2009年11月经临床超声诊断为复杂性先天性心脏病而行CCTA检查的患儿,35例患儿采用常规双筒双相注射方案,即注射2.0-2.5ml/kg的造影剂后再注射等量的生理盐水,91例患儿采用2次稀释扫描方案,首先按年龄体重大小给予1.0-1.5ml/kg的碘普罗胺(370mg/ml),以0.4-2.8ml/s流率经脚背静脉或手背静脉注入5-30ml;接着采用30%造影剂配以70%生理盐水混合稀释注射,造影剂用量为0.5-0.7ml/kg,注射速度0.5-2.8ml/s,最后以相同流率追加4-25ml纯生理盐水做最后稀释。由两名高年资心脏影像诊断医师回顾分析两组右心高浓度造影剂伪影的清除程度及动脉显影的对照,应用spss15.0forwindows数据库软件包进行统计。结果126例先天性心脏病中,男70例,女56例,中位年龄2.8岁,平均心率85-159次/min。在二组扫描方案中,未发现年龄、体重和心率的显著性差异(P值均大于0.05)。两组方案显示分次稀释替代组右室CT密度衰减值高于常规双相组(p0.01),而右心的造影剂条纹放射伪影(由于上腔静脉和右房造影剂浓度过高造成的条纹方放射状伪影)则远小于双相注射组(p0.01)。相比之下,左室结构显影在二组方案中无明显差异。右心结构的显影分次稀释组远好于双相注射组。结论分次稀释替代技术在儿童心脏CT血管成像的应用能有效避免和清除右心伪影,同时提供高质量的心腔肌束等结构特征图像,较适宜应用于儿科尤其是婴幼儿心血管CT检查。

The role of Split-Bolus injection of Diluted Contrast Medium in pediatric low-dose cardiac CT angiography

Objective To discuss the role of a split-bolus contrast medium injection protocol in the cardiac chambers and coronary arteries at pediatric cardiac computed tomographic（CT）angiography. Methods Patients who had undergone clinically indicated contrast enhanced 64-section multi-detector row CT angiography of the heart at Guangzhou children ＇ s hospital between May 2008 and November 2009.Over this period, 126 patients had undergone 64-section cardiac CT angiography. The human research committee approved this study and waived informed consent： 35 were injected by using a biphasic protocol with a dual-syringe injector; and 91 were injected by using a split-bolus protocol with a dual-syringe injector and an initial bolus of contrast medium with 1.2-1.5ml/kg rate followed by 1.0-1.5ml/kg speed of a 70%：30% saline to contrast medium mixture and a 4-25ml saline chaser. Two radiologists rated the visualization of right and left heart structures and the degree of streak artifacts. Data were analyzed with one-way analysis by spssvl5.0 for windows. Results Data for 56 girls and 70 boys （mean age,2.8 years）wereincluded. Mean contrast medium attenuation in the right heart was significantly（P〈.01）higher in the split-bolus group than in the biphasic injection group. For the left heart and the coronary arteries, there were no significant differences among the three groups. Artifacts occurred less frequently（P〈.01）in the biphasic than in the split-bolus groups. Visualization of right heart structures was rated significantly（P〈. 05）better in the split-bolus group than in the biphasic groups, while there was no differ- ence for visualization of left heart structures. Conclusion Split-bolus injection provides sufficient attenuation for visualization of the cardiac chamber and muscle structure in children, while streak artifacts from high attenuation contrast material can generally be avoided and arterial attenuation is maintained. It quite suits for the cardiac CT angiogra phy in pediatrics.