Heart motion adapted cine phase-contrast flow measurements through the aortic valve

A method for magnetic resonance cine velocity mapping through heart valves with adaptation of both slice offset and angulation according to the motion of the valvular plane of the heart is presented. By means of a subtractive labeling technique, basal myocardial markers are obtained and automaticall y extracted for quantification of heart motion at the valvular level. The c aptured excursion of the basal plane is used to calculate the slice offset and angulation of each required time frame for cine velocity mapping. Throu gh-plane velocity offsets are corrected by subtracting velocities introduce d by basal plane motion from the measured velocities. For evaluation of the method, flow measurements downstream from the aortic valve were performed both with and without slice adaptation in 11 healthy volunteers and in four patients with aortic regurgitation, Maximum through-plane motion at the ao rtic root level as calculated from the labeled markers averaged 8.9 mm in t he volunteers and 6.5 mm in the patients. The left coronary root was visibl e in 2-4 (mean: 2.2) time frames during early diastole when imaging with a spatially fixed slice. Time frames obtained with slice adaptation did not c ontain the coronary roots. Motion correction increased the apparent regurgi tant volume by 5.7 +/- 0.4 ml for patients with clinical aortic regurgitati on, for an increase of approximately 50%. The proposed method provides flow measurements with correction for through-plane motion perpendicular to the aortic root between the valvular annulus and the coronary ostia throughout the cardiac cycle. Magn Reson Med 42:970-978, 1999. (C) 1999 Wiley-Liss, I nc.