MEASUREMENT OF ABSOLUTE EPICARDIAL CORONARY-ARTERY FLOW AND FLOW RESERVE WITH BREATH-HOLD CINE PHASE-CONTRAST MAGNETIC-RESONANCE-IMAGING

Background Noninvasive measurement of absolute coronary arterial flow and coronary flow reserve would be of considerable use in the diagnosi s and management of patients with coronary artery disease. Phase-contr ast magnetic resonance imaging (MRI) has been used to measure flow in a variety of vessels. The goal of the present study was to determine i f MRI measurements of coronary artery flow in a single breath-hold can be used to determine flow reserve and the severity of pericardial ste nosis. Methods and Results In eight mongrel dogs, a closed chest model of partial left anterior descending coronary artery (LAD) occlusion w as created. Coronary flows in the left circumflex artery (LCx) and LAD were measured at rest and during adenosine infusion using velocity-en coded, breath-hold MRI and perivascular ultrasound (US) flowmeters. MR I measurements of absolute coronary flow and coronary flow reserve wer e highly correlated with US (r=.96 and .94, respectively). Flow reserv e measured in the constricted LAD was significantly lower than that in the unconstricted LCx by both US (P=.002) and MRI (P=.011). Conclusio ns MRI measurements of coronary flow and flow reserve were in good agr eement with US measurements. In addition, MRI measurements of coronary flow reserve successfully discriminated stenotic from normal vessels. These results indicate that MRI is a useful method for the noninvasiv e assessment of coronary flow and stenosis.