Magnetic resonance velocity mapping of normal transtricuspid velocity profiles.

To investigate the velocity profiles of transtricuspid inflow, we examined 20 normal subjects (17 males and 3 females, mean age 27 +/- 7) by the magnetic resonance imaging (MRI). Electrocardiographic gating was performed in all anatomical and flow studies, and sequences were triggered by the R wave. Cine gradient echo images (echo time, 14 ms) were acquired in the right ventricular horizontal long axis, and from these, cine images with velocity mapping were obtained in the short axis of the right ventricle. Velocity mapping of right ventricular inflow was obtained at peak early diastolic filling. Velocity profile curves across the tricuspid inflow were obtained at each 1 cm interval from the tricuspid ring to 3 cm into the cavity. Maximum/mean velocity was 1.1 +/- 0.1 at ring level, unchanged at 1 cm from the tricuspid ring, and thereafter increased to 1.4 +/- 0.3 at cm2, and 1.5 +/- 0.3 at 3 cm as peak velocity fell. The ratio of the longest and shortest jet width cross section was 1.3 +/- 0.3 at ring level, and increased to 1.5 +/- 0.3 at 3 cm from ring level. Jet cross sectional area was 10.4 +/- 2.1 cm2 at ring level, and was unchanged at 3 cm level. Thus, tricuspid inflow velocity showed a relatively flat profile at the tricuspid ring and tip level, becoming more dispersed at 2 and 3 cm from the ring. Right ventricular inflow jet cross section was elliptic, and appeared to be relatively constant in the cross-sectional area.