A method is provided that determines velocity encoding direction of volumetric image data sets comprising three-directional velocity information (V0, V1, V2) of a target volume, which involves:a) defining a coordinate system (X, Y, Z)b) determining all the possible arrangements of the three velocity components (V0, V1, V2) along the three coordinate axes (X, Y, Z)c) determining reference point or points in the target volume either automatically or upon user inputd) determining streamlines for each point for all possible combinations of velocity components as determined in b) ande) considering as velocity encoding direction the arrangement of the three velocity components corresponding to the streamlines having the longest length or a length above a threshold.A corresponding apparatus and computer program are also disclosed.
