Magnetic resonance imaging and cochlear implants: Compatibility and safety aspects

With cochlear implants, magnetic resonance imaging (MRI) has until recently been contraindicated due to excessive magnetic and electromagnetic interference. The aim of this study was to determine the MRI compatibility of the Med‐El Combi 40/40+ cochlear implant, within a wide range of clinical MRI applications. In vitro experiments on a 1.5 T MR scanner were performed. Torque, force, demagnetization, artifacts, induced voltages, and temperature increase were measured in worst case scenarios for the implant. In addition, stabilization experiments were performed. It was shown that most of the electromagnetic interferences between the cochlear implant and the 1.5 T scanner remained within acceptable limits. One exception is the torque on the internal magnet, which represents a hazard for patients with these cochlear implants. Therefore, MRI examination should only be performed if there is a strong medical indication, and certainly some assessment of the relative risks involved versus the risk of not providing the diagnostic capabilities of MRI, will have to be made. Appropriate safety measures should be taken. J. Magn. Reson. Imaging 1999;9:26–38 © 1999 Wiley‐Liss, Inc.