A method for performing Magnetic Resonance Imaging (MRI) guided core biopsies is tendered more accurate and efficient by precisely positioning a disengaged probe assembly with respect to a localization fixture attached to a breast coil platform. The precise position is defined by MRI stereotopic location of suspicious tissue with respect to a fiducial marker on the localization fixture. With the probe inserted, dual lumens in the probe assembly are used for drainage or insertion of fluids as well as inserting diagnostic and therapeutic tools. Core biopsies are performed by engaging a biopsy instrument handle containing a cutter, with the localization fixture providing support and position to the handle. Repeated MRI scans are facilitated by the ability to disengage the handle without risk of displacing the probe assembly from the biopsy site.