Magnetic resonance imaging after cochlear implants

Abstract

IntroductionMost cochlear implants are currently compatible with magnetic resonance imaging (MRI) up to 3 T. Nevertheless, this does not completely eliminate the risk of serious accidents. Implant displacements and other adverse events with compatible implants have been reported in the literature.Case reportsAmong the six patients who had MRI after receiving implants at our center, we report three cases with adverse events related to the examination. The first case was complicated by magnet displacement with partial demagnetization. The second case showed total demagnetization, which necessitated removal and reimplantation of the implant. The third case involved severe pain sensation which disrupted the MRI scan. The smallest artifact was found with 3D MRI angiography, and largest artifact was found with diffusion and T2 FLASH.DiscussionMoving the patient into the MRI apparatus must be supervised by an otorhinolaryngology specialist or an experienced radiologist. It is important to consider the magnetic field directions, so that angle between the implant magnetic fields and the MRI B0 always remains less than or equal to 90°. In addition, we recommend the use of an “arrow drawing” to facilitate the orientation of the magnetic field directions. Furthermore, to prevent magnet displacement, we recommend systematic use of a protective splint in addition to bandaging.

Cochlear Implantation in Neurological Patients: Case Report and Literature Survey

“…and the exam could be incomplete. In a previous study, Bawazeer et al reported larger artefacts on DWI and FLASH sequences; intermediate artefacts on T1, T2, and T2 FLAIR sequences; and small artefacts on MRI angiography sequences 4 ; whereas in a human cadaver study Wagner et al found significant improvement of the image quality and diagnostic usefulness both at 1.5 T and 3 T after magnet removal, with residual artefacts masking the peripheral areas of ipsilateral lobes and cerebellum and with strongest artefacts on T1 multiplanar reconstruction and constructive interference in steady state sequences. 5 When looking for contralateral hemisphere changes, removal of the magnet is not mandatory, but the exam should be carried out by following recommendations provided by manufacturer.…”

Difficulties With Magnetic Resonance Imaging in Patients With Cochlear Implants: A Review

“…There are also possibilities of displacing the magnet in the implant, demagnetizing the implant magnet, and causing pain to the patient during the MRI. Sometimes the pain is very severe and it is impossible complete the MRI examination [8,9,13].…”

“…Sometimes, the magnet returns to its original setting by itself after the test, but this does not always happen. Displacement of the magnet can be verified by CT scans or X-rays and sometimes it is necessary to replace the whole implant, requiring surgical intervention [8,9,14,15].…”

“…Today, thanks to the development of technology and numerous studies on the subject, safe doses of electromagnetic radiation and appropriate guidelines have been established. The aim of the study was to review difficulties related to the performance of magnetic resonance imaging in patients with CIs [7,8].…”

MRI‐related FDA adverse event reports: A 10‐yr review

“…The purpose of this article was to provide an overview of 10 yr (2008–2017) of FDA adverse event reports for MR systems. While previous studies have looked at adverse events in specific patient populations, particularly those with implanted medical devices (e.g., cochlear implants, pacemakers or defibrillators, breast tissue expanders, magnetically controlled growing rods) or specific imaging studies (e.g., fMRI), our goal was to provide a broad characterization of the types of adverse events that occur in the MR environment. Unlike previous studies, we did not limit our analysis to only thermal or auditory injuries.…”