基于左心室和冠状动脉动态体模系统观察不同心率下CT图像重建最佳期相

Optimal phases of reconstructed CT images under different heart rates based on dynamic phantom system of left ventricle and coronary arteries

目的观察以左心室和冠状动脉动态体模系统模拟左心室及冠状动脉运动时在不同心率下重建CT图像的最佳期相。方法构建可模拟50~120次/分心率下心脏周期性运动及心电信号输出的左心室和冠状动脉动态体模系统。于体模系统R-R间期行CT扫描,0~90%期相范围内每10%间隔重建图像。评估观察者间主观评估图像质量结果的一致性;对不同心率、不同期相图像进行比较。结果观察者间主观评价图像质量结果的一致性较高(Kendall W=0.83,P<0.05)。设定体模心率为50~60次/分时,大部分期相下重建图像质量均为良好,尤以30%、70%及80%期相最佳(P均<0.05);心率为65~75次/分时,最佳重建期相为40%、70%及80%(P均<0.05),以舒张期图像质量较好;心率80~95次/分时,30%为最佳重建期相(P均<0.05);心率为100次/分及以上时,所有期相重建图像质量均较差。结论以左心室和冠状动脉动态体模系统模拟左心室及冠状动脉运动时,不同心率下CT图像最佳重建期相不同;心率高于100次/分后所有重建图像质量均不佳。

Objective To explore the optimal phases of reconstructed CT images under different heart rates based on dynamic phantom system simulating the motion of left ventricle and coronary arteries.Methods A dynamic phantom system which could simulate the periodic movements of the heart at 50—120 beats per minute(bpm)and the output of electrocardiogram signals was constructed.CT scanning were performed in the simulated R-R interval,and images were reconstructed with every 10%interval between 0 to 90%phases.Then subjective image quality scoring was performed,and inter-observer consistency of image quality scores was assessed.Finally the qualities of reconstructed images were compared among different phases under different heart rates.Results The inter-observer consistency of subjective imaging quality scores was high(Kendall W=0.83,P<0.05).Under 50—60 bpm simulated heart rates,good reconstructed image qualities were obtained at most phases,especially at 30%,70%and 80%(all P<0.05).When simulated heart rates were set as 65—75 bpm,the best reconstructing phases included 40%,70%and 80%(all P<0.05),and images obtained in diastolic phase were better.Under 80—95 bpm,the best reconstructing phase was 30%(all P<0.05).When the simulated heart rate reached 100 bpm and above,the reconstructed image qualities were poor at all phases.Conclusion The optimal reconstructed phases were different under different heart rates based on dynamic phantom system simulating the motion of left ventricle and coronary arteries.When the simulated heart rate reached 100 bpm and above,the qualities of reconstructed images were poor under all phases.