第3代双源CT低剂量技术在高心率冠脉成像中的应用

Comparison of low-dose coronary CT angiography in patients with high heart rate using third-generation dual-source CT

目的:分析第3代双源CT低剂量扫描方案应用于高心率患者冠状动脉成像的图像质量及辐射剂量。方法:收集102例接受第3代双源CT冠状动脉成像检查的患者,扫描时采用前瞻性心电门控,并且选取CARE kV"on"模式调节管电压。根据心率(Heart Rate,HR)将患者分为3组:A组(36例):HR≤70次/分(bmp),B组(35例):70<HR<90次/分和C组(31例):HR≥90次/分。对比剂剂量设定为0.6 mL/kg,流率为对比剂剂量/10(mL/s)。图像质量客观评价包括有效辐射剂量、信噪比及冠脉主要分支的CT值、对比噪声比。图像质量主观评价采用4分法,大于2分定义为可评估血管。结果:ABC各组的辐射剂量分别为(1.3±0.7)mSv、(2.1±0.9)mSv、(1.7±0.7)mSv,A组明显低于B组(P=0.001),其余客观图像质量参数在三组间差异均无统计学意义(均有P>0.05)。三组图像质量平均评分无显著性差异(P>0.05)。三组图像(A、B、C)可评估节段率分别为99.23%、96.03%、88.21%,差异无统计学意义。结论:第3代双源CT低剂量扫描方案可以为高心率患者冠状动脉成像提供良好的质量图像,同时大大减少有效辐射剂量。

Objective:To compare the image quality and ionized-radiation dose of low-dose coronary CT angiography in patients with different heart rates using third-generation dual-source CT.Methods:One hundred and two patients who underwent coronary angiography by the third-generation dual-source CT were enrolled in the study.All images were acquired by the prospective ECG gated technique,with the CARE kV"on"mode to adjust the tube voltage.The patients were divided into 3 groups according to heart rate(HR):group A(n=36):HR≤70 bpm,group B(n=35):70 bmp<HR≤90 bmp and group C(n=31):HR>90 bmp.The dose of contrast was 0.6 mL/kg,and injection rate was volume/10(mL/s).The effective radiation dose,noise and signal noise ratio(SNR)were compared.Besides,CT value and contrast noise ratio(CNR)of coronary arteries were also analyzed.The image quality on a per-vessel basis was judged(both on a scale 1-4,with 4 being the best).Results:The effective radiation dose in group A was(1.3±0.7)mSv,which was significantly lower than that in group B[(2.1±0.9)mSv](P=0.001).No other significant difference in quantitative image quality was found among the three groups(P>0.05).Mean segment-based image quality scores showed no significant difference between the three groups(P>0.05).The evaluation rates of coronary artery segments in group A(99.23%)was the best(group B,99.03%and group C,98.21%).Conclusion:Third-generation dual-source CT low-dose scan protocol provides high image quality for patients with different heart rates.Moreover,it can greatly reduce ionized-radiation dose.