64层螺旋CT低剂量冠状动脉成像的临床应用

目的:应用心电门控管电流调节模式,降低冠状动脉成像辐射剂量。方法:76例患者被随机分为2组,标准组与低剂量组各38例。应用回顾性心电门控管电流调节模式进行冠状动脉成像,其他扫描参数不变,标准组在R-R周期的40%~80%使用管电流660 mA,其余时相使用280 mA;低剂量组在40%~80%R-R时相管电流输出值为550 mA,其余时相为110 mA。计算2组图像的平均SNR、CNR及每组ED值,进行组间比较。结果:2组图像平均SNR分别为122.2±29.69和121.69±31.58,平均CNR分别为8.61±1.17,9.05±1.86,进行组间t检验,P值>0.05,均无显著性差异。2组平均ED值分别为(25.01±2.54)mSv和(18.14±1.40)mSv,进行组间t检验,P值为1.40±10-18,有显著性差异,低剂量组ED值较标准组降低了约27.5%。结论:采用电流调节模式进行冠状动脉成像,分别降低心动周期不同时相管电流输出值,在保证图像质量的同时,明显降低了冠状动脉成像有效剂量。

Clinical application of reduction dose of 64-MSCT coronary angiography

Objective： To compare image quality and radiation dose in patients who underwent 64-slice computed tomography coronary angiography performed with different tube current modulation values. Methods： Seventy-six cases were randomly divided into two groups, 38 included in each group. All patients underwent 64-slice computed tomography coronary angiography using eleetrocardiographically controlled tube current modulation. For the standard group, the maximum current was set to 660mA during the cardiac phase 400/00-80% of the R-R cycle and was reduced in the other phase to a minimum of 280mA, and the maximum current was set to 550mA during the cardiac phase 40 %-80 % of the R-R cycle and was reduced in the other phase to a minimum of 110mA for the reducing dose group; in two groups, signal-to-noise ratio （SNR） and contrast-to-noise ratio （CNR） and the mean effective doses were calculated and compared respectively. Results.. All patients were performed successfully the examinations, mean SNR in two groups were 122.2±29.69 and 121.69±31.58, mean CNR were 8. 61±1.17 and 9.05 ± 1.86 respectively. There was no statistical difference between SNR and CNR for standard group with those for reducing dose group. Mean ED obviously decreased from （25.01±2.54）mSv of standard group to （18.14±1.4）mSv of reducing dose group. There were significant differences between mean ED in standard group with that in reducing dose group, compared with standard group, mean ED of reducing dose group reduced about 27.5 %. Conclusion： Using electroeardiographically controlled tube current modulation, coronary angiography in dose reduction group decrease increasingly mean ED to the patients, further acquire the high image quality.