A series of image data sets of a region of an organism is acquired while the acquired region of the organism moves dependent on breathing and heartbeat, and supplied to a processor. The processor determines a first contour that moves depending on the breathing in the acquired image data sets. The acquired image data sets are distorted elastically in the processor into singly distorted image data sets such that the first contours of the singly distorted image data sets spatially correspond with one another. A second contour is determined in the processor in the acquired image data sets or in the singly distorted image data sets, this second contour moves depending on the heartbeat. The singly distorted image data sets are distorted elastically into doubly distorted image data sets such that the second contours of the doubly distorted image data sets spatially correspond with one another. Regions of the doubly distorted image data sets that spatially correspond to one another are evaluated in the processor across image data sets.