Phase contrast images (A) and time-mean velocity curves (B) of the mitral (MV) and tricuspid (TV) valves in diastolic phase. A magnitude image in left upper corner of A shows typical arrangement of the cardiac valves. The remainders are velocity images. The numbers represent the phase numbers in a cardiac cycle. Only the images for phases 8-20 are shown. Black signal in TV and MV areas represent forward flow though the valves. Images 8 and 9 show flow signal in MV area but no signal in TV area. The time-mean velocity curves in B show delayed onset and peak of the TV E-wave. The straight elements of the E-waves of the TV and MV flow curves are extrapolated to the baseline and the delay time (double-headed arrow) of the onset of the TV flow is measured. AV, aortic valve; PV, pulmonary valve.