Abstract: Objective To evaluate the image quality of free-breathing non-contrast-enhanced 3D-TFE-WH sequences in different segments of coronary artery and their ability to display lumen stenosis. 
Methods Ten volunteers were recruited as the research subjects and underwent coronary magnetic resonance angiography(MRA) and CT angiography(CTA) on the same day. The image quality of MRA and CTA was evaluated, and the ability of coronary MRA to display lumen stenosis was evaluated with coronary CTA as the standard. 
Results There were 90 segments of coronary arteries in 10 volunteers, of which 83 segments(92.2%) met the diagnostic requirements by coronary MRA and 90 segments(100.0%) by CT. There was no significant difference in image quality of proximal and mid segment blood vessels between two methods(P＞0.05). The image quality score of MRA in the distal segment of left anterior descending branch, left circumflex branch and right coronary artery was lower than that of CTA(P＜0.05). MRA showed a total of 6 segments of lumen stenosis, including 2 segments of slight stenosis and 4 segments of mild stenosis. CTA showed 8 segments of lumen stenosis, including 6 segments of slight stenosis and 2 segments of mild stenosis. Taking CTA as the standard, MRA overestimated stenosis in 4 segments and underestimated stenosis in 5 segments. Two sections of CTA showed slight stenosis, which could not be evaluated by MR. The consistency of the two examination methods in the ability of lumen stenosis was medium(Kappa value=0.656). 
Conclusion The image quality of free-breathingnon-contrast-enhanced 3D-TFE-WH sequence in proximal and mid segment of coronary artery and its ability to display non-mild lumen stenosis are similar to CTA. This technique can be used as a method for coronary artery disease screening in people with contraindication of contrast agents.

Key words: coronary vessels, magnetic resonance angiography, computed tomography angiography