A Moveable 3-Tesla Intraoperative Magnetic Resonance Imaging System

Abstract

Based on success with a prototype 1.5T intraoperative magnetic resonance imaging (iMRI) system and the desire for increased signal-to-noise ratio, along with its relationship to image quality and advanced applications, a 3.0T system that uses the same novel moveable magnet configuration was developed. To assess clinical applicability by prospectively applying the higher-field system to a neurosurgical cohort. Upgrading to 3.0T required substantial modification of an existing iMRI-equipped operating room. The 1.5T magnet was replaced with a ceiling-mounted, moveable 3.0T magnet with a 70-cm working aperture. Local radiofrequency shielding was replaced with whole-room shielding. A new hydraulic operating table, high-performance gradients, and advanced image processing software were also installed. The new system was used as an adjunct to standard neurosurgical practice. The iMRI system upgrade required 6 months. Since completion, the 3.0T iMRI system has successfully guided neurosurgery in 120 patients without system failure in a patient-focused environment. Intraoperative image quality was superior to that obtained at 1.5T and enabled intraoperative acquisition of advanced imaging sequences, including tractography. Intraoperative imaging was found to modify surgery in a substantial number of patients. Implementation of an iMRI system based on a moveable 3.0T magnet is feasible. From clinical experience with 120 patients, iMRI at 3.0T is safe, reliable, and capable of directing image-guided surgery with exceptional image quality.