Physician/Neurosurgeon Carle Foundation Hospital Urbana, Illinois, United States
Introduction: The use of 7 Tesla (T) magnetic resonance imaging (MRI) is expanding across neurosurgical and spinal surgical specialties. However, few neurosurgical-related implants have been tested for safety at 7T, limiting its use in patients with instrumented spine surgery, cranial fixation, and ventriculoperitoneal (VP) shunts. Implant safety can be determined via the American Society for Testing Materials International (ASTM) guidelines. This systematic review seeks to summarize all neurosurgical-related implants that have been tested for safety in 7T MRI.
Methods: A systematic search adherent to PRISMA guidelines was performed using PubMed, MEDLINE, Web of Knowledge and citation matching. Studies written in English that included at least one neurosurgical implant and at least one safety outcome were included. Data were extracted for implant studied, implant composition, deflection angle, torque, temperature change, and ASTM guidelines followed.
Results: Overall, 18 studies consisting of 45 unique implants were included. Implants included: cranial fixation devices, aneurysm clips, spinal rods, pedicle screws, VP shunts, deep brain stimulation devices, and electroencephalogram (EEG) caps and electrodes. Cranial fixation devices, deep brain stimulation devices, spinal rods, and pedicle screws are likely 7T MRI compatible based on outcomes reported. Aneurysm clips and EEG devices had variable safety outcomes. The programmable VP shunts studied lost functionality after 7T MRI exposure.
Conclusion : We identified several spinal and neurosurgical implants that are likely compatible with 7T MRI. Given the growth in 7T imaging and expansion of the technology, neurosurgical implants should be constructed with the aforementioned safety considerations. Caution must be taken with all implants, especially aneurysm clips, programmable VP shunts, and EEG recording devices.
