Initial experience with intraoperative magnetic resonance imaging in spine surgery

Study Design: A case series of 12 patients who underwent spine surgery in an intraoperative magnetic resonance imager (IMRI). Objectives: To determine the advantages, limitations, and potential applications to spine surgery of the IMRI. Summary of Background Data: Existing stereotactic navigational systems are limited because images are obtained before surgery and are not updated to reflect intraoperative changes. In addition, they necessitate manual registration of fiducial landmarks on the patient's anatomy by the surgeon to the previously obtained image data set, which is a potential source of error. The IMRI eliminates these difficulties by using intraoperative acquisition of MRI images for surgical navigation with the capacity for both image update and image-guided frameless stereotaxy. The IMRI is a novel cryogenless superconducting magnet with an open configuration that allows the surgeon full access to the patient during surgery and intraoperative imaging. Methods: T1- and T2-weighted fast spin echo images were obtained for localization, after surgical exposure and after decompression during the course of 12 spine surgeries performed in the IMRI. Results: The authors performed a series of 12 procedures in the IMRI that included three lumbar discectomies, three anterior cervical discectomies with allograft fusion, three cervical vertebrectomies with allograft fusion, two cervical foraminotomies, and one decompressive cervical laminectomy. The system provided rapid and accurate localization in all cases. The adequacy of decompression by MRI during surgery was confirmed in 10 of 12 cases. Conclusions: The IMRI provided accurate and rapid localization in all cases and confirmed the adequacy of decompression in the majority of cases. Future applications of the IMRI to spine surgery may include intraoperative guidance for resection of spine and spinal cord tumors and trajectory planning for spinal endoscopy or screw fixation.