1. A method of processing volumetric anatomic data and vector field data from volumetric phase-contrast magnetic resonance imaging (MRI) data to evaluate the physiology of a heart and vessels, comprising: (a) a computer obtaining said volumetric phase-contrast (MRI) data from a magnetic resonance imaging system, wherein said volumetric phase-contrast (MRI) data comprises said volumetric anatomic data and said vector field data; (b) said computer applying volumetric phase-error correction to said volumetric-phase contrast MRI data; (c) said computer visualizing on a display said corrected volumetric-phase contrast MRI data by superimposing said vector field data on said volumetric anatomic data; (d) using said visualization of (c) to select and view planes in said volumetric phase-contrast (MRI) data; and (e) using said selected planes to delineate boundaries of said heart, said vessels or a combination thereof for said computer to obtain measurements.