Left ventricular diastolic early and late filling quantified from 4D flow magnetic resonance imaging

The purpose of this study was to investigate the value of 4D flow MRI for mitral filling measurements, using transthoracic echocardiography (TTE) and 2D flow MRI as references, as well as identify relationships with age and left ventricle (LV) remodeling in healthy volunteers.

Fifty healthy volunteers (22 men, 28 women; mean age, 51.3 ± 16.9 [SD] years; age range: 20-80 years) prospectively underwent TTE and MRI on the same day. 4D flow volume acquisition was done at 3T with reconstructed spatial/temporal resolutions: 1 × 1.48 × 2.38 mm³/34 ms. Early (E) and late (A) flow rate and maximal velocity peaks were measured from 4D flow data with three strategies: static planes at 1) the mitral valve leaflets tip (4D_LT) and 2) annulus (4D_ann); and 3) while tracking the annulus through time (4D_track).

4D_LT- and 4D_track-derived E/A ratios were in good agreement with 2D flow and TTE estimates with a superiority over maximal velocities (4D_LT: r = 0.71 and r = 0.66; 4D_track: r = 0.74 and r = 0.71, respectively) of flow rates (4D_LT: r = 0.89 and 0.72; 4D_track: r = 0.91 and 0.76, respectively). Measurements of 4D_LT and 4D_track were highly reproducible (ICC = 0.89 and 0.95, respectively) and significantly correlated with age and LV remodeling (4D_LT: r = -0.76 and ρ = -0.49; 4D_track: r = -0.79 and ρ = -0.51, respectively).

E/A ratio can be accurately measured using 4D flow MRI either at a fixed mitral leaflet tip location or through annulus plane time-resolved tracking.