Aortic regurgitation: quantitation with MR imaging velocity mapping.

Aortic regurgitation (AR) in five healthy volunteers and 26 patients (mean age, 60.3 years; range, 25-83 years) was quantitatively measured with magnetic resonance (MR) imaging velocity mapping. Cine transverse images of the ascending aorta (32 phases per cardiac cycle) were acquired by using a gradient-echo sequence with a velocity-encoding bipolar pulse applied in the section-selection direction with a 1.5-T MR imaging unit. The aortic flow was calculated by integrating the product of area and mean velocity of the ascending aorta at each phase over a cardiac cycle. The negative and positive velocity values indicated antegrade and regurgitant flow, respectively, which allowed calculation of forward and regurgitant flow. Inter- and intraobserver variation of regurgitant fraction (RF) measurement was small (r = .956, standard error of the estimate [SEE] = 1.2%, n = 31; and r = .998, SEE = 0.35%, n = 10, respectively). RF determined with MR imaging agreed well with Doppler echocardiographic (n = 26) and aortographic (n = 9) grading of AR. Reproducible, quantitative, and noninvasive measurement of AR is possible with MR velocity mapping.