Streamline superimposed on vortex cores. Sample Streamline visualization of cross-sectional view of LV flow during peak early filling (a) peak late filling (b) showing pair of counter-rotating vortices. Streamlines are color coded (blue to red) based on velocity magnitude. Same frames were superimposed with 3D vortex ring cores identified using Lambda2-method and showing good overlap between the 3D Lambda2-detected vortex cores and the cores of corresponding 2D streamlines’ counter-rotating vortices during both peak early (c) and peak late filling (d). Lambda2 isovalue threshold was used to define the isosurfaces of vortex ring cores (with μ as the λ2 average of voxels with λ2 < 0).