RF heating of implanted spinal fusion stimulator during magnetic resonance imaging

RF heating of an implanted spinal fusion stimulator during MRI was studied on a full size human phantom. Heating during MRI scans was measured with RF transparent fiberoptic sensors. With the implant correctly connected, the maximum temperature rises were less than 2°C during the 26-minute maximum power scans. At a broken stimulator lead (connecting the generator and the electrodes) tip, the maximum temperature rise was 11-14°C. Regular scans of 4 minutes for spinal cord examination produced similar temperature elevations. After the generator and the leads were removed, heating at the electrode connector tip was noticeable but less than 1.5°C. The control temperature rises at the same locations, without the stimulator, were less than 0.5°C. This study shows that spinal fusion stimulator heating is within the FDA safety guideline of 2°C. However, if a lead wire is broken, it is unsafe during MRI scans