Intraoperative MRI for Stereotactic Biopsy

Abstract

This work aims at demonstrating the value of intraoperative magnetic resonance imaging (ioMRI) as a routine tool for stereotactic brain biopsy. Biopsies were done using the PoleStar N-20 ioMRI (Medtronic Navigation, Louisville, Colorado, USA) under general anesthesia. Images were acquired after patient positioning and after insertion of an MRI-compatible biopsy cannula. A Navigus guide (Medtronic Navigation) was used to align and direct the cannula. Retargeting was done as necessary, to improve placement within the target and to avoid critical structures, using the system's integrated infrared navigation tool. Cannula placement was tracked using serial images. ioMRI-guided biopsy was done in 39 patients, of whom 28 had neoplasms and 11 had non-neoplastic conditions. Additional OR time related to the use of ioMRI (including positioning of the patient and magnet, and imaging acquisition) averaged 1.1h. In 53% of the surgeries the biopsy cannula was repositioned based on intraoperative imaging. A histologic diagnosis was obtained in all but one patient, with ioMRI confirming proper cannula placement in all cases. There were no significant hemorrhages on clinical or imaging grounds nor any other complications. IoMRI can be routinely used for stereotactic biopsy in a regular neurosurgical operating environment. While general anesthesia is used and there is some additional time incurred from this technology the improved diagnostic yield and ability to avoid complications make ioMRI an ideal technical adjunct for brain biopsy.