Initial study of snapshot freeze on the image quality of coronary CTA

ZHANG YanJun; WANG Jingzhi; ZHANG Yanhong

Abstract：Objective To assess the application value of snapshot freeze ( SSF) in improving the image quality of coronary CTA.Methods Twenty patients were performed coronary computed tomographic arteriography (CTA), and all of them under-went coronary angiography in a week .The images with the optimal phase were reconstructed by conventional method and SSF re -spectively.The coronary artery was divided into 15 segments.Two radiologists assessed the image quality using a 5 score scale. The diameter of coronary artery segments showed in the image of CTA and coronary angiography were measured .The measurement results were analyzed .The patients ' average heart rate and the heart rate changes were recorded .CT value of the right coronary artery ( RCA) was measured .The relationship between RCA CT value , average heart rate , heart rate changes and the subjective scoring of the image was rreconstructed with SSF .Results The subjective scoring of the image reconstructed by conventional method and SSF were 3.83 ±0.62, 4.49 ±0.71;the differences and relationship between the two methods were statistically sig-nificant ( Z =-5.17, r =0.76, P =0.00).The coronary artery segments diameter of conventional reconstructing method , SSF and coronary angiography were (2.59 ±0.79) mm, (2.57 ±0.81) mm and (2.48 ±0.82) mm respectively;the differences be-tween three groups were not statistically significant ( F =0.27, P =0.77).The CT value of the coronary artery reconstructed by conventional method and SSF were (284.57 ±106.76) HU and (296.15 ±101.89) HU respectively, the differences between two groups were not statistically significant ( t =-0.73, P =0.48).The relationship was different between the subjective sco-ring of the image reconstructed using SSF with CT value , verage heart rate and heart rate changes ( r =0.73、-0.52、-0.52, P<0.05).Conclusion SSF can correct motion artifact of coronary artery , improve the image quality of CTA, and not affect the measurement result accuracy .