1. A method for correcting the background phase in magnetic resonance phase contrast flow images, the method comprising the steps of: providing a time series of velocity encoded magnetic resonance images of a patient, wherein said time series of velocity encoded images comprises for each time point a phase contrast image wherein a pixel intensity is proportional to a flow velocity; measuring, for each pixel, a change of intensity over the time series of phase contrast images; identifying pixels with a low measure of temporal change as stationary pixels; and calculating a correction field for the stationary pixels, wherein said correction field represents a background phase to be subtracted from the phase contrast image.