Accelerated acquisition is required to make 4D flow MRI clinically feasible. In this study, three commonly used acceleration approaches are compared. Validation of flow volume and velocity assessment is performed in phantoms and comparison against conventional 2D phase-contrast is done across the aortic and mitral valve in 25 healthy volunteers. 4D flow MRI with echo-planar-imaging shows largest in vitro error in velocity assessment, however, the bias is within clinically acceptable margins. In volunteers, 4D flow MRI with echo-planar-imaging produces most reliable quantitative results in flow volume and velocity and presents the shortest acquisition time with satisfactory image quality.