An MRI-guided interventional system for use with a patient and an interventional device includes a base, a trajectory guide frame, and a mounting device. The base is configured to be secured to a body of the patient. The trajectory guide frame includes a targeting cannula. The targeting cannula has an elongate guide bore extending axially therethrough, defining a trajectory axis, and being configured to guide placement of the interventional device. The trajectory guide frame is operable to move the targeting cannula relative to the base to position the trajectory axis to a desired intrabody trajectory to guide placement of the interventional device in vivo. A plurality of patient engagement structures are provided on the base and are configured to penetrate tissue of the body and to space the base apart from the tissue. The system further includes a plurality of fasteners configured to secure the base to the body.