Three-dimensional, time-resolved motion of the coronary arteries

Background. Coronary artery motion can decrease image quality during coronary magnetic resonance angiography and computed tomography coronary angiography. Purpose. To characterize the three-dimensional motion of the coronary arteries along the entire vessel length and to identify the temporal location and duration of periods of relatively low cardiac motion in patients with coronary artery disease. Methods. Archived digital, biplane x-ray angiography films acquired at 30 frames per second with simultaneous electrocardiogram recording were reviewed for 15 patients with coronary artery disease. The right coronary (RCA), left anterior descending (LAD), and left circumflex (LCX) arteries were divided into proximal, mid, and distal segments. The displacement and velocity of a point in each segment were calculated throughout the heart cycle. Time-dependent, three-dimensional motion of each segment on each vessel was determined. Periods of the heart cycle during which maximal displacement was less than 1 mm or 0.5 mm per frame for each artery were determined. Results. A period lasting an average of 187 msec was seen during mid-diastole (72±5% of the cardiac cycle) in which all three coronary arteries studied had relatively little motion. This period of quiescence was consistent along the length of the arteries. Although the amount of motion did vary along the length of the arteries, there was no difference in the timing of rest periods in the proximal, mid, and distal segments using a <1 mm per frame threshold. The periods of low motion were significantly reduced in length and often altogether eliminated when the 0.5 mm per frame threshold was used.