1. A method for motion correction of emission computed tomography data in a combination device for magnetic resonance tomography and emission computed tomography, comprising: introducing an examination object into an examination region of the combination device; recording emission computed tomography data over a measurement period and storing associated detection events and detection instants; measuring magnetic resonance data of at least two subregions of the examination region at at least two instants during the recording period of the emission computed tomography data and storing the measured magnetic resonance data and the recording instants, determining at least one item of motion information which describes a motion of the examination region of the examination object at a first instant relative to a position at a second instant from the magnetic resonance data recorded at the first instant and the second instant, for each subregion; determining a motion model which describes motion of the examination object, for the entire examination object, from the motion information for the subregions; and calculating the motion-corrected emission tomography data from the detection events, the detection instants and the motion model.