Magnetic resonance tomography apparatus has a device whose spatial orientation can be modified in order to define a spatial orientation of a tomogram, and whose spatial position can be modified in order to define a spatial position of the tomogram, these definitions taking place before the exposure of a tomogram or acting on an existing three-dimensional image data set. The device has a planar stamped part in the form of a plate, or a display surface or has an oblong stamped part, the device is not fastened to the apparatus or at least, is not fastened to it fixedly, or is fastened to it via a carrier device, and the orientation and position of the device is acquired by position sensors.