Safety and efficacy assessment of MRI in cochlear implant patients with retained magnets

Abstract

Most patients with CI need to undergo radiation diagnostics during their lifetime, including magnetic resonance imaging (MRI) and computed tomography (CT). Modern cochlear implants are currently compatible with MRI up to 1.5 T. However, clinics conducting magnetic resonance imaging studies may refuse to diagnose. This is due to the fact that during the study, the MRI scanner will act on the magnet of the implant and this can lead to such complications as migration of the implant, its demagnetization, and pain. These doubts determined the goal of our study - to assess the safety and effectiveness of magnetic resonance imaging (MRI) with a magnetic field power of 1.5 T in patients with cochlear implants (CI). We analyzed MR images of 11 patients who were followed up at the St. Petersburg Research Institute of Ear, Throat, Nose and Speech from 2014 to 2020, diagnosed with bilateral sensorineural hearing loss, grade IV, condition after CI. A questionnaire was conducted to determine the side effects of the study and to assess the diagnostic effectiveness of the method by several radiologists. In order to prevent possible complications, an external, tight-fitting pressure bandage was applied to all patients, and a plastic splint was installed in the projection of the implant in the bandage. During the study, the orientations of the magnetic fields of the MRI scanner (B0) and the implant (B1) were considered. The analysis of the obtained results showed that the MRI procedure with a magnetic field power of 1.5 T in patients with CI was not accompanied by any complications for patients and a negative effect on the implant. It is important to note that the diagnostic efficacy of the MRI results was maintained.