The invention provides the use of a physiologically tolerable manganese compound or a salt thereof, substantially free from hydrophilic polymer components containing a significant amount of a Mn2+- chelating unit, in the manufacture of an enterally, e.g. orally or rectally, administrable MRI contrast medium composition for use in a method of imaging of a human or non-human animal body which has fasted for a period of at least 6, preferably at least 10, more preferably at least 12 hours before enteral administration of said composition. It has been found that diagnostically effective levels of uptake of orally or rectally administered manganese may be achieved using this method.