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Published on: July 5, 2021
Intraoperative magnetic resonance imaging-guided neurosurgery at 3-T
Charles L Truwit1, Walter A Hall
1Department of Radiology, Hennepin County Medical Center, University of Minnesota, Minneapolis, Minnesota 55415, USA. truwit@umn.edu
Objective:
Between 1997 and 2004, more than 700 neurosurgical procedures were performed in a 1.5-T magnetic resonance-guided therapy suite. During this period, the concept of high-field intraoperative magnetic resonance imaging (MRI) was validated, as was a new surgical guidance tool, the Navigus (Image-guided Neurologics, Melbourne, FL), and its methodology, prospective stereotaxy. Clinical protocols were refined to optimize surgical techniques. That implementation, the "Minnesota suite," has recently been revised, and a new suite with a 3-T MRI scanner has been developed.
Methods:
On the basis of experience at the initial 1.5-T suite, a new suite was designed to house a 3-T MRI scanner with wide surgical access at the rear of the scanner (opposite the patient couch). Use of electrocautery, a fiberoptic headlamp, a power drill, and MRI-compatible neurosurgical cutlery was anticipated by inclusion of waveguides and radiofrequency filter panels that penetrate the MRI suite's radiofrequency shield. An MRI-compatible head holder was adapted for use on the scanner table. A few items exhibiting limited ferromagnetism were used within the magnetic field, taking strict precautions.
Results:
During the initial procedures (all magnetic resonance-guided neurobiopsies), the new suite functioned as anticipated. Although metallic artifact related to titanium needles is more challenging at 3 T than at 1.5 T, it can be contained even at 3 T. Similar to 1.5 T, such artifact is best contained when the device is oriented along B0, the main magnetic field. Surgical needles, disposable scalpels, and disposable razors, despite being minimally ferromagnetic, were easily controlled by the surgeon.
Conclusion:
An intraoperative magnetic resonance-guided neurosurgical theater has been developed with a 3-T MRI scanner. Intraoperative imaging is feasible at this field strength, and concerns regarding specific absorption rate can be allayed. Infection control procedures can be designed to permit neurosurgery within this environment. Despite the increase in magnetic field strength, safety can be maintained.
