Coronary Artery Motion in Electron Beam Tomography

Purpose: The purpose of this work was to evaluate coronary artery motion characteristics and determine optimal electron beam tomography (EBT) scan time during the cardiac cycle to image the coronary arteries. Method: This study evaluated the movement of coronary arteries in 20 EBT cine studies, at rest and during stress, obtained for evaluating coronary artery disease. The proximal, middle, and distal segments of each coronary artery were measured at multiple times during the cardiac cycle. The motion distance (mm) and velocity (mm/s) of each segment of the coronary arteries were then measured to establish the motion that occurs in the x and y axes during different times in the cardiac cycle. Results: Coronary artery velocity ranged from 22.4 to 108.6 mm/s. The least motion (and slowest speed) occurred between 30–50 and 40–60% of the R-R interval at rest and stress, respectively. The right coronary artery moved the greatest in the x and y planes (highest speed and spatial change), followed in decreasing order by the circumflex, left main, and left anterior descending arteries. The phase of the cardiac cycle with the greatest coronary artery motion was between 0 and 20% of the R-R interval. Conclusion: Coronary artery motion varies greatly throughout the cardiac cycle. To minimize cardiac motion during tomographic imaging of the coronary arteries, we recommend 40–50% R-R interval as an electrocardiographic trigger time and avoiding the use of image acquisition times of >100 ms.