Intra-operative MRI at 3.0 Tesla: A Moveable Magnet

This paper presents the development and implementation of an intra-operative magnetic resonance imaging (ioMRI) program using a moveable 3.0 T magnet with a large working aperture. Methods: A previously established prototype 1.5 T ioMRI program based on a ceiling-mounted moveable magnet was upgraded to 3.0 T. The upgrade included a short, 1.73 m, magnet with a large 70 cm working aperture (IMRIS, Winnipeg, Canada), whole-room radio-frequency shielding, and a fully functional MR-compatible operating room (OR) table. Between January and September 2009, 100 consecutive patients were evaluated at 3.0 T. Results: The ioMRI upgrade maintained a patient-focused environment. When not needed for surgery, the magnet was moved to an adjacent room. A large aperture and streamlined OR table allowed freedom of patient positioning while maintaining access and visibility. Working at 3.0 T enabled application of advanced imaging sequences to the full spectrum of neurosurgical pathology in the ioMRI environment. The use of ioMRI continues to show unsuspected residual tumor in up to 20% of cases. There were no adverse events or technical system failures. Conclusion: An ioMRI program based a 3.0 T moveable magnet is feasible. By moving the magnet, the system maintains a patient-focused surgical environment and the ability to share the technology between medical disciplines.