MRI Safety with Cochlear Implants up to Three Tesla – Experiences by Performing an In Vitro Test

Objective: This study aimed to quantify the demagnetization of the magnet of a new Cochlear Implant with removable magnet in a 1.5 T and a 3.0 T MRI scanner in vitro.

Study design: Experimental cadaver head model. Subjects and Methods: Ten implant magnets were examined through a routine protocol in a 1.5 T and 3.0 T MRI scanners. Magnetization prior to and after the experiment was measured.

Results: No statistically relevant change in the magnetization of the magnets was observed for in the surrounding of the MRI scanner or the isocenters of the 1.5 T and 3.0 T scanners. No protective head bandage was required to prevent implant movement. In our experience, magnet replacement is a minimally invasive surgical procedure requiring about 15 minutes.

Conclusion: Demagnetization of the CI with removable magnet did not occur at 3.0 T MRI. However, to improve the quality of diagnostic imaging in patients with ipsilateral brain disease removal of the implant magnet is recommended.