A magnetic resonance (MR) coil unit, comprising: —an MR coil body which houses at least one MR coil, the MR coil body having a front surface for facing a patient, a reverse surface opposite to the front surface, and at least one opening through the MR coil body which connects the front and reverse surfaces; —at least one MR marker located at least partly in said at least one opening in the MR coil body; and—at least one optical marker located above the reverse surface of the MR coil body.