Coronary artery motion in electron beam tomography

Purpose: The purpose of this work was to evaluate coronary artery motion ch aracteristics and determine optimal electron beam tomography (EBT) scan tim e during the cardiac cycle to image the coronary arteries. Method: This study evaluated the movement of coronary arteries in 20 EBT ci ne studies, at rest and during stress, obtained for evaluating coronary art ery disease. The proximal, middle, and distal segments of each coronary art ery were measured at multiple times during the cardiac cycle. The motion di stance (mm) and velocity (mm/s) of each segment of the coronary arteries we re then measured to establish the motion that occurs in the x and y axes du ring 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 in terval at rest and stress, respectively. The right coronary artery moved th e greatest in the x and y planes (highest speed and spatial change), follow ed in decreasing order by the circumflex, left main, and left anterior desc ending 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 cy cle. To minimize cardiac motion during tomographic imaging of the coronary arteries, we recommend 40-50% R-R interval as an electrocardiographic trigg er time and avoiding the use of image acquisition times of >100 ms.