Image Quality Improvement in MRI of Cochlear Implants and Auditory Brainstem Implants After Metal Artifact Reduction Techniques.

OBJECTIVE

Observe if metal artifact reduction (MAR) techniques applied to magnetic resonance imaging (MRI) performed on patients with cochlear implants (CI) or auditory brainstem implants (ABI) improves image quality.

STUDY

DESIGN

Retrospective review.

SETTING

Tertiary care center.

PATIENTS: Patients with auditory implants who underwent clinical MRI before and after the application of MAR techniques previously described.

INTERVENTIONS: From September 2022 to March 2023, patients who underwent brain or internal auditory canal (IAC) MRI with and without MAR were identified. Sequences included T1 and T2 weighted with turbo-spin-echo (TSE) correction and fluid-attenuation inversion recovery (FLAIR). Images were analyzed for visualization of intracranial structures by two neuroradiologists.

MAIN OUTCOME MEASURES: Visibility of 14 structures graded on a four-point Likert scale. Average scores per structure and sequence were compared using paired two-tailed t -tests and change in mode score.

RESULTS

Ten patients underwent pre- and post-MAR MRI. Six had a unilateral CI, three had a unilateral ABI, and one had an ABI and CI. Three patients had four devices with the internal magnet removed for both scans. All structures had significantly improved visibility on post-MAR scan except ipsilateral parietal and occipital lobes and contralateral inner ear. Mode score increased from 2 to 4 for the ipsilateral occipital lobe and from 3 to 4 for the ipsilateral semicircular canals, brainstem, and cerebellar peduncles. Significant improvement was seen in all sequences except for ipsilateral structures on T1w axial precontrast and contralateral structures on T1w coronal postcontrast. ABIs did not improve as much as CIs because they scored better on the pre-MAR scan.

CONCLUSIONS

MAR techniques improve image quality for patients with MRI-compatible implants with magnets. Benefits may be more evident in CIs than ABIs.