The study of snapshot freeze on correcting the right coronary artery motion artifact

ZHANG Yanjun; WANG Jingzhi; ZHANG Yanhong; YUAN Zhenguo

Abstract：Objective To assess the effect of snapshot freeze (SSF) in correcting the right coronary motion artifact and to analyze influencing factors.Methods 267 patients were collected,who underwent coronary computed tomographic arteriography (CTA).The images with the optimal phase were reconstructed by conventional method and SSF respectively.Three radiologists assessed the image quality using a 5-score scale.We recorded the patients'average heart rate and the heart rate changes and measured CT value of the right coronary artery (RCA).The relationship between RCA CT value,average heart rate,heart rate changes and the subjective scoring of the image reconstructed with SSF was analyzed.Results The average heart rate and heart rate changes of the patients was 69.71 ± 10.58 and 3.66 ± 2.54 beats percent minute.The diameter of 1068 section vessels reconstructed by conventional method and SSF were (2.55 ± 0.46) mm and (2.54 ± 0.62) mm,there was no statistically significance (t =0.81,P =0.65).The CT value of the coronary artery reconstructed by conventional method and SSF were (273.57 ± 108.12) HU and (289.37 ± 98.76) HU,respectively.The differences between two groups were not statistically significant (t =-0.69,P =0.39).The subjective scoring of the image reconstructed by conventional method and SSF were 3.25 ± 0.54 and 4.76 ±0.35,the differences between two groups were statistically significant (Z =-5.17,P ＜ 0.01).Motion artifacts on the right coronary artery paragraph 2 (RCA2) was Maximum,the subjective scoring of the image reconstructed by conventional method and SSF were 3.01 ±0.61 and 4.32 ±0.22,the differences between two groups were statistically significant (Z =-4.32,P ＜ 0.01).There was correlation between the subjective scoring of the image reconstructed by conventional method and SSF (r =0.81,P ＜0.01).The relationship between the subjective scoring of the image reconstructed with SSF with RCA CT value,average heart rate,heart rate changes were significantly (r =0.67,-0.49,-0.47,P ＜ 0.05).Conclusion SSF can correct motion artifact of RCA,and improve the image quality.The larger the patient's heart rate,the worse the image quality after SSF reconstructed.