Abstract
OBJECTIVE: To determine the optimal reconstruction phase and acquisition time window of coronary computed tomography angiography (CCTA) in patients with different heart rates based on prospective ECG-gating and to compare the image quality and radiation dose between the whole cardiac cycle mode and optimized acquisition time window. MATERIALS AND METHODS: One thousand patients(536male, mean age ± standard deviation, 57.43 ± 11.73years) who underwent CCTA were divided into two groups, group A (n = 500)and group B(n = 500). According to the heart rate at the time of CCTA, the subjects were divided into subgroups A1 and B1 (< 51 bpm), A2 and B2 subgroups (51-55 bpm), A3 and B3 subgroups (56-60 bpm), A4 and B4 subgroups (61-65 bpm), A5 and B5 subgroups (66-70 bpm), A6 and B6 subgroups (71-75 bpm), A7 and B7 subgroups (76-80 bpm), and A8 and B8 subgroups (81-85 bpm), A9 and B9 subgroups (> 85 bpm). Group A individuals underwent CCTA within a single cardiac cycle and the optimal reconstruction phase at each heart rate was identified based on image quality. The ideal acquisition time window was determined by considering the 95% confidence interval of the best reconstruction phase, which was equivalent to the average value of the best reconstruction phase (standard deviation × 2). The individuals in group B were examined within the optimal collection time window. Compare the radiation doses and image quality of patients in groups A and B. RESULTS: The findings indicated that the A1-A9 subgroups' optimal reconstruction phase and acquisition time window were: 61%~85% RR interval; 68%~84% RR interval;70%~82% RR interval and 34%~46% RR interval; 70%~82%RR interval, and 34%~46% RR interval;70%~82% RR interval and 36%~48% RR interval; 65%~89% RR interval and 38%~50% RR interval;68%~84% RR interval and 36%~56%RR interval; 38%~54% RR interval; 38%~58% RR interval. No statistically significant difference was observed in terms of Signal-to-Noise Ratio(SNR), and Contrast-to-Noise Ratio(CNR) between group A and group B, (P > 0.05). The average effective radiation dose(ED) values in Group B were 42.6%, lower than in Group A, (P < 0.001). CONCLUSIONS: Ideal acquisition phase and acquisition-time windows vary among individuals with varying heart rate(HR). Narrowing the acquisition timeframe based on prospective electrocardiogram(ECG)-gating can considerably lower the radiation dose of CCTA imaging while maintaining image quality.