QUANTIFICATION OF THE AORTIC REGURGITANT VOLUME WITH MAGNETIC-RESONANCE PHASE-VELOCITY MAPPING - A CLINICAL INVESTIGATION OF THE IMPORTANCEOF IMAGING SLICE LOCATION

Background and aims of the study: Current techniques for assessment of aortic regurgitation (AR) are mainly qualitative. Magnetic resonance phase velocity mapping (PVM) provides accurate measurements of arteria l blood blow. in AR, the aortic regurgitant volume (ARV) can be quanti fied with a single imaging slice measurement in the ascending aorta, T he aim was to use PVM to: (i) quantify the regurgitant volume in patie nts with AR using an in vitro validated technique; and (ii) confirm in vivo our previous in vitro findings of the importance of measurement location, Methods: Four healthy volunteers and 19 patients with AR, va rying from mild to severe, were examined in a 1.5 Tesla MRI scanner. I n 13 patients, the slice was placed: (i) between thp aortic valve and the coronary ostia; (ii) at the sinotubular junction (SJ); and (iii) 2 cm above the SJ. In six patients, one measurement was taken as close as technically possible to the aortic valve, PVM measurements of the A RV were compared with angiographic/echocardiographic AR grading, Resul ts: No ARV was measured in healthy subjects, In patients, PVM results correlated well with angiographic/echocardiographic data. Repeatabilit y of the PVM results was excellent and interobserver variability very small. The measured ARV decreased as the slice distance from the aorti c valve increased, due ts aortic compliance, in agreement to previous in vitro results. Close to the valve, acceleration did not affect the accuracy of velocity measurements, Conclusions: PVM has great potentia l to measure AR ist a purely quantitative manner, Measurement location is important and results suggest that the closer the measurement to f ire valve the more accurate the ARV quantification.