Coronary arteries: Retrospectively ECG-gated multi-detector row CT angiography with selective optimization of the image reconstruction window

PURPOSE: To investigate how the technique of retrospective gating can be us ed to optimize reconstruction of multi-detector row computed tomographic (C T) images for each of the three major coronary arteries during the cardiac cycle. MATERIALS AND METHODS: Multi-detector row coronary CT angiograms obtained i n 50 patients were reconstructed at 20%-80% of the cardiac cycle in increme nts of 10%. Two blinded independent reviewers assessed the image quality, i n terms of artifacts and visibility, obtained with three-dimensional postpr ocessing for segments 1-3 (right coronary artery), segments 5-8 (left main and left anterior descending coronary arteries), and segments 11 and 12 (le ft circumflex artery). The following grades were assigned: 1, very poor; 2, poor; 3, fair; 4, good; and 5, excellent. RESULTS: The left anterior descending artery was best visualized in middias tole at 60%-70% of the cardiac cycle, and the left circumflex artery was be st visualized at 50%. The optimal reconstruction window for the right coron ary artery was significantly different at 40% (P < .05). Although there was good agreement (kappa = 0.75) between the two reviewers, there was a high degree of variation in the patient population. CONCLUSION: The image reconstruction window for CT angiography of the coron ary arteries should be adapted to each coronary artery. The use of one fixe d time point in the cardiac cycle for image reconstruction does not provide optimal image quality.