Abstract: Objective To explore the feasibility and application value of 320-Multi-Detector CT(320-MDCT) for free-breathing coronary CT angiography (CCTA) in the elderly patients. Methods A total of 100 elderly patients who underwent CCTA scanning using 320-MDCT at Zhongda Hospital Southeast University from October 2022 to May 2023 were selected retrospectively. The patients were divided into free-breathing group (n=50) and breath-holding group (n=50) based on their respiratory status during the scan. The CT values, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) of the aorta, right coronary artery (RCA) and left main coronary artery (LM) and effective dose (ED), standard deviation (SD) of pericoronal adipose tissue in the two sets of images were measured and compared. Two physicians used a 4-point method to perform a double-blind evaluation of the image quality of 15 coronary segments in the two groups, and Mann-Whitney U test was used to evaluate the subjective ratings. Kappa test was used to assess inter-rater agreement of the two physicians. Results The differences in CT values, SNR and CNR of aorta, RCA and LM between the two groups were not statistically significant (P>0.05).There was no significant difference in subjective scores between the two groups and the same results were observed in the high heart rate group (>75 bpm) and the medium-low heart rate group (≤75 bpm) (P >0.05). The consistency of subjective scores between the two physicians was good (kappa values were 0.633 and 0.720), and the level of ED in the free-breathing group was lower than that in the breath-holding group (P <0.05). Conclusions Free-breathing CCTA may be feasible on 320-MDCT with high image quality and low radiation dose in the elderly patients.

Key words: 320-MDCT, free-breathing, coronary CT angiography