多层螺旋CT冠状动脉造影图像质量的影响因素分析

The influence factors in image quality of multi-slice spiral CT coronary angiography (MSCTA)

目的探讨心率对多层螺旋CT冠状动脉造影图像质量的影响和最佳重建相位窗的选择。方法回顾性分析67例患者16层螺旋CT心电门控条件下冠状动脉造影图像。按心率分成≤60次/min、61～70次/min、71～80次/min和≥81次/min分成第1～4组,将冠状动脉图像按伪影多少及血管连续性分为1～3分,评价心率与图像质量的关系,并优选出各组显示冠状动脉的最佳相位窗。结果对每位患者4条冠状动脉(右冠状动脉、左冠状动脉主干、左前降支、左回旋及图像质量进行研究。心率≤60次/min,可用于分析的图像占86.7%;心率61～70次/min,可用于分析的图像占62.5%;心率71～80次/min,可用于分析的图像占40%;心率≥81次/min,可用于分析的图像占12.5%。第1、2组与第3、4组间冠脉总的检查成功率有统计学差异(P<0.05)。第1组所有冠状动脉节段以75%相位窗为最佳;第2组冠状动脉节段以75%为最佳相位窗占89.5%,第3组左右冠状动脉以45%和75%为最佳相位窗分别占45%和55%,第4组全部冠状动脉节段以45%为最佳相位窗。结论心率对多层螺旋CT冠状动脉造影图像质量有重要影响;心率70次/min以下冠状动脉最佳相位窗通常为75%,心率71次/min以上时,应该以30%～90%多相位重建。

Objective To evaluate the influence of heart rate on image quality of multi-slice spiral CT coronary angiography（MSCTA） and the optimization of image reconstruction windows. Methods Retrospectively ECG-gated MSCT coronary angiography were performed in 67 cases. The cases were divided into four groups by heart rate, groupl with heart rate less than 60 beats per minute（bpm）, group 2 with heart rate 61-70 bpm, group 3 with heart rate 71-80 bpm and group 4 with heart rate over 81 bpm. The impact of heart rate on image quality of MSCTA and the optimization of image reconstruction windows were evaluated. Results 4 coronary （RCA,LM,LAD,LCX） segments were analyzed in each patients with regard to image quality.86.7%（112/128） of the coronary segments were sufficient for analysis in patients with heart rate less than 60 bpm,62.5%（55/88） with 61-70 bpm,40%（8/20） with 71-80 bpm and 12.5%（2/16） with heart rate over 81 bpm, respectively. There were statistically significances between every coronary segments of group 1 and 2, group 3 and 4 （P〈0.05）. All coronary segments of group 1 were optimally visualized on the image reconstructed at 75% image reconstruction window of cardiac cycle; 89.5% cases at 75% in group 2;for group 3,55% of coronary artery were best presented at 75% image reconstruction window,45% of coronary artery at 45%; All coronary segments of group 4 were optimally visualized on the image reconstructed at 45% image reconstruction window. Conclusion Image quality of MSCT coronary angiography is highly dependent on heart rate. Coronary artery is usually best shown at 75% image reconstruction window of cardiac cycle for those with heart rate less than 70 bpm.30%-90% image reconstruction should be performed when heart rate is over 71 bpm.