The invention relates to an imaging system for imaging a region of interest comprising a moving object, which moves less in small motion phases than in large motion phases. Detection values are provided and a small motion determination unit (15) determines the motion of the object in the region of interest in the small motion phases from the 5 detection values. A large motion determination unit (16) determines the motion of the object in the large motion phases from the determined motion of the object in the small motion phases. A reconstruction unit (17) reconstructs an image of the region of interest from the detection values, wherein the reconstruction unit (17) is adapted for performing a motion compensation using the determined motions in the small and large motion phases.