Cardiac nuclear magnetic resonance imaging compared with Doppler echocardiography to estimate pulmonary vein and left ventricular diastolic flow

The authors compared cardiac nuclear magnetic resonance imaging (Vectra, 0.5 T) to Doppler echocardiography in the noninvasive estimate of intracardiac flow patterns. By comparing NMR signal-intensity curves and Doppler flow patterns within the left ventricle, the authors obtained a relation between Doppler velocities and NMR signal intensities in absolute units (100 AU=7 cm/sec, r=0.74). This allowed the estimate of flow velocity of the pulmonary veins in normal subjects and patients with previous infarction (most of them without technically feasible evaluation of pulmonary vein inflow velocity to the left atrium). Moreover, in 8 patients with left ventricular aneurysm, an estimate of flow within the lesion was possible; 30% of them had technically unsatisfactory Doppler flow velocity estimates. NMR signal intensities were very low throughout the cardiac cycle and correlated to thrombus formation (p<0.001 for maximum systolic AU<100 and p<0.03 for maximum diastolic AU<200).