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.