Magnetic resonance imaging and cochlear implants: compatibility and safety aspects

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Otolaryngology

Background:

• Cochlear implants (CIs) have historically been contraindicated for Magnetic Resonance Imaging (MRI) due to potential magnetic and electromagnetic interference.
• Assessing the safety of specific CI models is crucial for expanding diagnostic imaging options for patients with hearing loss.

Purpose of the Study:

• To evaluate the MRI compatibility of the Med-E1 Combi 40/40+ cochlear implant system.
• To quantify various electromagnetic interference parameters under simulated clinical MRI conditions.

Main Methods:

• In vitro testing of the Med-E1 Combi 40/40+ CI on a 1.5 T MR scanner.
• Measurement of torque, force, demagnetization, artifacts, induced voltages, and temperature increase.
• Performance of stabilization experiments under worst-case scenarios.

Main Results:

• Most electromagnetic interferences between the Med-E1 Combi 40/40+ CI and the 1.5 T scanner were within acceptable safety limits.
• A significant torque was observed on the internal magnet, indicating a potential hazard for patients.
• Artifacts, induced voltages, and temperature increases were generally within tolerable ranges.

Conclusions:

• The Med-E1 Combi 40/40+ cochlear implant exhibits partial MRI compatibility at 1.5 T.
• The identified torque hazard necessitates stringent safety protocols and careful risk-benefit analysis before performing MRI on patients with this implant.
• MRI should only be considered when medically essential, with thorough evaluation of risks versus diagnostic benefits.