An RF coil assembly for use with magnetic resonance imaging (MRI) apparatus is described. The RF coil assembly comprises one or more coil elements capable of receiving electromagnetic radiation and is capable of being directly attached to a stereotactic base ring. The RF coil assembly may comprise a localiser box having fiducial markers. A corresponding attachment apparatus is also described for optimising the attachment position of a stereotactic base ring to a subject's head. The attachment apparatus comprises one or more fixing elements that allow the attachment apparatus to be releasably attached to a stereotactic base ring. In one embodiment, the internal dimensions of the attachment apparatus are selected to be substantially the same as the internal dimensions of an RF coil assembly. Corresponding methods are also described.