心率对16层螺旋CT冠状动脉造影图像质量的影响及其重建相位窗的优选

目的探讨心率对16层螺旋CT冠状动脉造影图像质量的影响及其重建相位窗的优选。方法本文收集接受16层螺旋CT冠状动脉造影(MSCTCA)检查者69例,按心率分成小于60次/min、61~65次/min、66~70次/min和大于70次/min共四个组,将冠状动脉图像质量根据冠状动脉伪影多少及血管连续性分为0~3分四个等级,评价不同心率对重建图像质量的影响,并分别优选出各组显示不同冠状动脉节段的最佳相位窗。结果第1组至第4组左冠状动脉及其分支的检查成功率分别为95%、93.3%、83.3%和50%,右侧冠状动脉分别为90%、93.3%、77.8%和50%。第3组和第4组间所有冠状动脉节段的成功率均有统计学差异(P<0.05)。第1组所有冠状动脉节段均以75%相位窗显示最佳;第2组显示两侧冠状动脉以75%为最佳显示相位窗者均占80%(12/15);第3组中左、右冠状动脉以75%为最佳显示相位窗者分别占72.2%和55.5%,右侧冠状动脉以45%为最佳显示相位窗者占33.3%;第4组病例显示左侧、右侧冠状动脉的最佳相位窗分布较分散,分别在75%~95%和35%~45%。结论对于16层螺旋CT来说,心率低于70次/min时冠状动脉检查可获得较高的检查成功率。心率低于65次/min时,两侧冠状动脉的最佳显示相位窗通常为75%;心率超过65次/min,尤其超过70次/min时,应选择35%~45%和75%~95%两个节段的多相位窗重建。

Impact of heart rate on image quality of 16-slice spiral CT coronary angiography and optimization of image reconstruction window

Objective To explore the impact of heart rate on the image quality of 16-slice spiral CT coronary angiography (MSCTCA) and optimization of image reconstruction window. Methods Sixty-nine cases who have accepted MSCTCA were divided into four groups by the heart rate, first group including 20 cases with heart rates less than 60 beats per minute (bpm), second group 15 cases with heart rates of 61-65 bpm, third group 18 cases with 66-70 bpm and fourth group with heart rate over 70 bpm. The image quality of MSCTCA was scored four grades from 0 to 3 by heart motion artifact and vessel continuity, and the impact of heart rate on the image quality of MSCTCA was assessed. The optimization of image reconstruction windows of different coronary segments were evaluated. Results From first to fourth group, the successful rate of examination of the left coronary artery and its main branches were 95%, 93.3%, 83.3% and 50%, respectively; and that of right coronary artery were 90%, 93.3%, 77.8% and 50%. Statistically significances exist between every coronary segments of third and fourth group (P<0.05). All coronary artery segments of first group were optimally visualized on the images reconstructed at 75% image reconstruction window of cardiac cycle; bilateral coronary artery of 80% cases(12/15) were best visualized at 75% image reconstruction window in second group; for third group, 72.2% of left coronary artery segments and 55.5% right coronary artery segments were best presented at 75% image reconstruction window, 33.3% of right coronary artery segments at 45% coronary artery segments; the optimal windows of image reconstruction of left and right coronary artery segments in fourth group were at 75%-95% and 35%-45%, respectively. Conclusion For 16-slice spiral CT, the higher successful rate of MSCTCA examination can be reached for cases with heart rate lower than 70 bpm. Bilateral coronary arterys usually were best shown at 75% image reconstruction window of cardiac cycle for cases with heart rate lower than 65 bpm. Both 35%-45% and 75%-95% image reconstruction should be performed when heart rate was over 65 bpm, espically over 70 bpm.