An imaging medical diagnosis apparatus has a display and operating device in which raw data of a region of an examination subject to be images can be stored, and an actuator with which a grouping of raw data can be defined, displayable at the display and operating device. In a method for operating a magnetic resonance apparatus at least two raw data sets divided into segments are generated in a time sequence from the same region of an examination subject and are stored in the diagnosis apparatus, and segments from both raw datasets that have been generated during a selectable time span of the time sequence are grouped to form a further raw dataset.