256层螺旋CT冠状动脉成像“双低”扫描的临床应用

Application of 256-slice CT coronary angiography with lower radiation dose and lower contrast medium

目的探讨256层螺旋CT低管电压、低对比剂用量("双低")扫描在冠状动脉疾病诊断中的应用价值。方法52例临床疑诊冠状动脉疾病于本院行256层螺旋CT前瞻性心电门控冠状动脉成像双低扫描(管电压80kV,对比剂用量0.8ml/kg)的患者资料(A组),均采用迭代重建算法iDose 5进行图像重建;50例行64层螺旋CT常规冠状动脉成像的患者资料作为对照组(B组),两组患者均行传统冠状动脉血管造影(CCG)检查。2名有经验的放射科医师按照15段分段法采用4级图像质量评分法评价两组患者的冠状动脉图像质量,并记录对比剂用量及辐射剂量,以CCG为准,评估两组冠状动脉CT成像的诊断准确率。结果所有患者均成功完成256层CT及64层CT冠状动脉成像。A组患者共显示冠状动脉677节段,以CCG为标准,敏感度为94.5%,特异度为97.4%,阳性预测值为92.7%,阴性预测值为98.0%,诊断准确率为96.6%。B组冠脉成像患者共显示冠状动脉631节段,敏感度为89.1%,特异度为96.4%,阳性预测值为89.9%,阴性预测值为96.1%,诊断准确率为94.5%。两组患者的平均对比剂用量分别为56.8ml和82.2ml,辐射剂量分别为1.46mSv和8.37mSv。结论 256层螺旋CT低管电压冠脉成像技术结合低对比剂用量及迭代重建算法可实现冠状动脉成像的"双低"扫描,与CAG对比有很好的一致性。

Objective To evaluate the application of 256-slice CT coronary angiography （CTCA） at reduced tube voltage and contrast medium dose .Methods 52 patients suspected with coronary arterial disease underwent 256-slice CTA （tube voltage 80 kV ,contrast medium dose 0 .8 ml/kg） ,the images were post-processed with an iterative reconstruction algorithm level of iDose 5（group A）;A control group of 50 patients underwent 64-slice CTA （group B） .Two groups were performed with conventional coronary angiography （CCG） .A 4-point scale was used for grading the overall image quality by 2 experienced radiologists .The sensitivity ,specificity ,positive predictive value （PPV） ,negative predictive value （NPV） and accuracy of CTA were evaluated .The radiation dose and contrast medium dose were recorded .Results Diagnostic CTA images were obtained in all patients .677 diagnostic coronary segments were evaluated in group A ,the sensitivity ,specificity ,PPV ,NPV and accuracy were 94 .5% ,97 .4% ,92 .7% ,98 .0% and 96 .6% ,respectively .631 diagnostic segments were evaluated in group B ,the sensitivity ,specificity ,PPV ,NPV and accuracy were 89 .1% ,96 .4% , 89 .9% ,96 .1% and 94 .5% ,respectively .The mean dose of contrast medium was 56 .8 ml for group A and 82 .2 ml for group B .The mean effective dose was 1 .46 mSv for group A and 8 .37 mSv for group B .Conclusion Combined use of low tube voltage ,low contrast medium dose and iterative reconstruction algorithm is more effective for reducing radiation dose and maintaining image quality in 256-slice CT coronary angiography .