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      Magnetic Resonance Imaging Artifacts and Cochlear Implant Positioning at 1.5 T In Vivo

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          Abstract

          Objective

          Cerebral magnetic resonance imaging with the magnet of the cochlear implant receiver/stimulator in place causes artifacts and hinders evaluation of intracerebral structures. The aim of this study was to evaluate the internal auditory canal and the labyrinth in a 1.5T MRI with the magnet in place.

          Study Design

          Observational study.

          Setting

          Tertiary referral center.

          Subjects and Methods

          The receiver/stimulator unit was placed and fixed onto the head of three volunteers at three different angles to the nasion–outer ear canal (90°–160°) and at three different distances from the outer ear canal (5–9 cm). T1 and T2 weighted sequences were conducted for each position.

          Results

          Excellent visibility of the internal auditory canal and the labyrinth was seen in the T2 weighted sequences with 9 cm between the magnet and the outer ear canal at every nasion–outer ear canal angle. T1 sequences showed poorer visibility of the internal auditory canal and the labyrinth.

          Conclusion

          Aftercare and visibility of intracerebral structures after cochlear implantation is becoming more important as cochlear implant indications are widened worldwide. With a distance of at least 9 cm from the outer ear canal the artifact induced by the magnet allows evaluation of the labyrinth and the internal auditory canal.

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          Most cited references13

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          Current clinical issues for MRI scanning of pacemaker and defibrillator patients.

          Dramatic increases in both magnetic resonance imaging (MRI) usage and cardiac device-based therapy have resulted in an estimated 50-75% probability of a patient being indicated for an MRI over the lifetime of their device. Some recent studies have demonstrated "safe procedures" and "no adverse events" in the limited populations, clinical situations, and specific devices and lead orientations tested. While these investigations are useful to help ascertain the hazards for patients with cardiac devices, they do not demonstrate clear freedom from risk. All components of active implantable systems must be engineered during the design stage to provide safety in current and evolving MR environments. Device manufacturers need to secure regulatory approval to confirm their products' safety under multiple clinical and technical variables.
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            MRI Artifacts and Cochlear Implant Positioning at 3 T In Vivo.

            To evaluate the assessment of the internal auditory canal and the labyrinth in relation to different CI magnet positions and MRI sequences at 3 T.
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              Artifacts caused by cochlear implants with non-removable magnets in 3T MRI: phantom and cadaveric studies.

              The aim of this study was to evaluate artifacts produced by cochlear implants (CI) during 3.0 Tesla (T) magnetic resonance imaging of the brain using different sequences on phantom and cadaveric specimens. A phantom and three cadaveric specimens with CIs were imaged using a 3.0 T clinical scanner. Artifacts were analyzed quantitatively and according to the sequence used. Different brain regions were evaluated for image distortion and limitation of diagnostic significance. In cadaver studies, all sequences generated signal-void areas around the implant. In T2-weighted sequences, additional periodic shadowing was discovered. Anatomical structures of the brain on the contralateral side of the CI were for the most part undistorted. At 3T, artifacts around CIs with non-removable magnets compromise image quality of the nearby brain regions and diagnosis of brain lesions is limited. In the contralateral hemisphere, diagnostic accuracy is only marginally limited.
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                Author and article information

                Contributors
                Journal
                Biomed Res Int
                Biomed Res Int
                BMRI
                BioMed Research International
                Hindawi
                2314-6133
                2314-6141
                2018
                8 November 2018
                : 2018
                : 9163285
                Affiliations
                Department of Otolaryngology, Head and Neck Surgery, Department of Radiology, Unfallkrankenhaus Berlin, Germany
                Author notes

                Academic Editor: Martin Kompis

                Author information
                http://orcid.org/0000-0001-8632-3721
                http://orcid.org/0000-0001-9693-9319
                Article
                10.1155/2018/9163285
                6250014
                30533442
                683986de-54e3-4e11-b65e-79d016997e78
                Copyright © 2018 Dirk Schröder et al.

                This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 25 August 2018
                : 31 October 2018
                Categories
                Research Article

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