The invention relates to a method for analyzing perfusion images, in particular MR pertbsion images, of a human or animal organ including the steps of: (a) defining at least one contour of the organ, and (b) establishing at least one perfusion parameter of a region of interest of said organ within a boundary defined by the at least one contour, whereby steps (a) and (b) are repeated in a series of iterative steps wherein for each subsequent iterative step the definition of the at least one contour in step (a) is varied, and the series of iterative steps is terminated after reaching an optimal value for the at least one perfusion parameter in step (b).