64层CT回顾性心电门控低剂量冠脉成像的临床研究

Low Dose 64-slice CT Coronary Angiography with Retrospective ECG Gating: A Clinical Study

目的:通过比较图像质量与辐射剂量,评价64层螺旋CT低剂量回顾性心电门控冠脉成像技术临床应用的可行性。方法:选取拟行CT冠状动脉造影的患者80例(心率小于65次/min,心率波动范围小于5次/min),所选患者分为两组,分别进行低剂量回顾性心电门控(40例,开启ECG管电流调制技术,70%～80%期相满电流输出)及常规回顾性心电门控(40例,35%～80%期相满电流输出)CT冠脉造影,依据患者体质量指数选择管电流(400～800 mA),管电压120 kV。比较两组的辐射剂量及图像质量。P<0.05认为差异具有统计学意义。结果:低剂量回顾门控组与常规回顾门控组图像质量差异无统计学意义(Z=-4.78,P=0.23)。低剂量回顾门控组CTCA辐射剂量平均(13.76±2.38)mSv,常规回顾门控组CTCA辐射剂量平均(20.06±3.35)mSv,差异有统计学意义(t=-8.39,P=0.00),使用低剂量回顾门控降低了31.4%的辐射剂量。结论:低心率患者行回顾门控CTCA通过修改ECG管电流调制技术参数得到的图像质量与常规回顾门控CTCA无差别,而辐射剂量显著减低。

Objective： To compare image quality and radiation dose for coronary artery computed tomographic angiograms（CTA） with retrospectively gated helical（RGH） CT technique in two methods using 64-slice spiral CT.Methods： 80 patients with low heart rate enrolled in this study were randomly divided into two groups.The low dose RGH group was 40 patients with average body mass index（BMI） 27.06 using ECG modulation technique（full mA on 70%～80% of the R-R interval and the lowest mA on rest of phases）.The traditional RGH group was 40 patients with BMI 25.66 using ECG modulation technique（full mA on 35%～80% of the R-R interval and the lowest mA on rest of phases）.Two groups were evaluated for image quality（each coronary artery segment,5-point scale） and radiation dose and compared with image quality score and radiation dose by Mann-Whitney U-test and unpaired t-test.A p value below 0.05 was considered statistically significant.Results： The mean effective dose for the low dose RGH group was 13.76 mSv;this represents a 31.40% reduction as compared with that for the traditional RGH group（mean,20.06 mSv;t =-8.391,P = 0.00）.The mean image quality score was 4.05 for images obtained with low dose ECG modulation technique versus 4.19 for images obtained with traditional ECG modulation technique（Z =-4.78,P = 0.23）.Conclusion： RGH coronary CT angiography using ECG modulation technique（full mA on 70%～80% of the R-R interval and the lowest mA on rest of phases） could offer assessable image quality and substantially reduced effective radiation dose compared with traditional RGH coronary CT angiography at low heart rate.