Implantable spinal fusion stimulator: Assessment of MR safety and artifacts

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Abstract
The objective of this investigation was to perform magnetic resonance (MR) imaging safety and artifact testing of an implantable spinal fusion stimulator. Magnetic field interactions, artifacts, and operational aspects of an implantable spinal fusion stimulator were evaluated in association with a 1.5 T MR system. Magnetic field‐related translational attraction was measured using the deflection angle test. A special test apparatus was used to determine torque at 4.7 T. Artifacts were characterized using fast multiplanar spoiled gradient‐echo, T1‐weighted spin‐echo, and T1‐weighted fast spin‐echo sequences. Operational aspects of the implantable spinal fusion stimulator before and after exposure to MR imaging at 1.5 T were assessed. In addition, nine patients (six lumbar spine and three cervical spine) with implantable spinal fusion stimulators underwent MR imaging. The findings indicated that magnetic field interactions were relatively minor, artifacts were well characterized and should not create diagnostic problems, and there were no changes in the operation of the spinal fusion stimulator. The nine patients underwent MR procedures without substantial adverse events or complaints. Based on the results of this investigation and in consideration of the findings from previous studies of MR imaging safety for the implantable spinal fusion stimulator, MR imaging may be performed safely in patients using MR systems operating at 1.5 T or less following specific recommendations and precautions. J. Magn. Reson. Imaging 2000;12:214–223.