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