BACKGROUND: Coronary CT angiography allows visualization of the coronary arteries. However, motion artifact can impair delineation of the coronary artery lumen and detection of coronary artery stenoses.

OBJECTIVE: We investigated the influence of heart rate and the segment of the cardiac cycle during which images are reconstructed on the occurrence of motion artifacts.

METHODS: We evaluated coronary CT angiography datasets obtained by 64-slice dual-source CT in 100 consecutive patients. Data were reconstructed at 13 time instants during the cardiac cycle and evaluated for the presence of motion artifact.

RESULTS: Mean heart rate was 66 +/- 14 beats/min. Overall, 98 of 100 patients had evaluable datasets. For heart rates <= 60 beats/min, optimal image quality was uniformly found during late diastole (100% of cases with evaluable image quality during a time window between 65% and 75% of the cardiac cycle). With increasing heart rates, images reconstructed during late systole more frequently provided best image quality. However, image reconstruction could not be restricted to a systolic time period. To achieve evaluable image quality in 95% of cases, data acquired between 25% and 75% of the cardiac cycle had to be available for patients with heart rates >60 beats/min.

CONCLUSION: Dual-source CT provides high image quality across a wide range of heart rates. Although data acquisition may be limited to diastole for patients with heart rates <= 60 beats/min, the availability of data acquired both during systole and diastole is necessary for patients with higher heart rates. (C) 2012 Society of Cardiovascular Computed Tomography. All rights reserved.