A device used in performing imaging magnetic resonance measurements (=MRI) in a Region of Interest (ROI) (9) of a small animal (3) with an MRI magnet system (7), with a cradle (5) on which the small animal (3) is lying, and with a radio-frequency (=RF) antenna (6), wherein the RF antenna (6) and the small animal (3) can be positioned relative to each other, characterized in that the device comprises a slide (1) on which the cradle together with the small animal immobilized thereupon can be moved both outside and inside the MRI magnet system, and characterized in that the RF antenna is rigidly fixed on the slide. This results in a device for the relative positioning of the small animal with respect to the RF antenna for an MRI measurement, which is easy to retrofit on existing tomography equipment, with which this positioning can be implemented both inside and outside the MRI magnet by simple handling and without great additional technical effort.