Objective To explore the scan technique and image quality of coronary angiography with dual source computed tomography（CT） without oral metoprolol preparation.Methods Plain and enhanced dual source CT coronary angiography without oral metoprolol preparation was prospectively performed in 600 patients.Calcium scoring with plain scan images as well as multi-planar reconstruction（MPR）

maximum intensity projection（MIP）

and volume rendering technique（VRT） reconstruction with enhanced scan images were performed in all cases.The scan technique and post-reconstruction experience was summarized.The image quality was classified as 1 to 4 points

and coronary segments classified according to the American Heart Association standards were evaluated.Results The average calcium score of the 600 cases was 213.6±298.7（0-3 216.5）.The average heart rate of the enhanced scan was 82.1±16.2（47-139） bpm.The post-reconstruction methods with which coronary segments could be shown as best as possible consisted of single phase reconstruction method

two or more phases supplemented method

and electrocardiogram editing method.Altogether 8 457 coronary segments were evaluated

among which 97.2% were evaluated as point 1

1.7% point 2

0.5% point 3

and 0.6% point 4.The coronary segments in 261 cases were completely normal

while 360 segments were diagnosed with <50% stenosis and 625 segments with ≥50% stenosis.Conclusions Excellent coronary artery image can be obtained with dual source CT in patients with any heart rate without oral metoprolol preparation.Heart rate is not a major source of the artifact

coronary segments can be well shown with single or multiple-phase reconstruction method.