25 - Coronary Artery and Sinus Velocity and Flow

Abstract

Assessment of blood flow in the coronary arteries is highly challenging because of their small size, tortuosity, and high mobility. In addition, flow velocities are low (requiring a sequence with high flow sensitivity) and phasic, peaking in diastole for the left anterior descending artery but with approximately equal flow peaks in systole and diastole for the right coronary artery. In the presence of disease, the temporal patterns of flow velocity through the cardiac cycle change, with diastolic flow velocities being reduced before systolic components are compromised. Assessment of total or global coronary flow can be made from measurements in the larger and less mobile coronary sinus, and this has been validated against positon emission tomography (PET). For flow in individual arteries, both breath-hold and navigator gated segmented gradient echo phase velocity mapping approaches have been developed at both 1.5 Tesla (T) and 3 T for the assessment of coronary flow and flow velocity and coronary flow reserve and coronary flow velocity reserve. More recently, the higher efficiency of interleaved spiral phase velocity mapping has allowed acquisitions of coronary blood flow with higher spatial and temporal resolution. Assessment of coronary blood flow and flow reserve has potential for the noninvasive assessment of the physiologic significance of coronary stenosis. In addition, through assessment of changes in cross-sectional area and coronary blood flow in response to isometric hand grip exercise, cardiovascular magnetic resonance provides a noninvasive method for assessing coronary artery endothelial dysfunction, a marker of atherosclerotic disease and an independent predictor of coronary events.