Intrakranielle, orbitale, sinunasale, nasopharyngeale und Felsenbein - Magnetresonanztomographie bei CI-Patienten – hinsichtlich Sicherheit, Implantatpositionierung und Artefaktbildung

Introduction: Due to the increasing focus on cost-effectiveness in healthcare and the need for well-founded indications before performing MRI (magnetic resonance imaging), this study aims to evaluate the diagnostic value of MRI imaging in Cochlear implant (CI) patients for intracranial, orbital, paranasal, nasopharyngeal and temporal bone assessments.

Methods: Two cadaveric heads were implanted in different angular positions (30°, 45° and 90°) uni- and bilateral with and without a magnet in situ. A probands head was similary wrapped with CI. Scans were performed with CI uni- and bilateral; with and without magnet. We performed 3 Tesla MRI analysis in CISS, T2, TIRM, diffusion weighted and T1mpr sequences. Cadaveric MRIs were then mapped with the neuroanatomy atlas CAT-12, in vivo cMRI sequences and artifact size was examined to determine the assessability of 42 defined structures.

Results: The software mapping analysis revealed substantial artifacting of intracranial structures, especially in the occipital lobe and brain stem. Even without the magnet, the artifact significantly interfered with visibility in the DWI of the middle ear, mastoid, and brain stem. In sequences involving the sphenoid sinus and nasopharynx, visibility was markedly reduced. However, the maxillary and frontal sinuses, ethmoid, and orbit were clearly visible in clinically relevant sequences.

Discussion: CI, especially with a magnet, reduces MRI visibility in most intracranial regions. Due to poor visualization in DWI even without a magnet, surgical exclusion of ipsilateral cholesteatoma suspicion is recommended in CI patients. MRI of the orbit and paranasal sinuses is adequate, but magnet removal is necessary for proper imaging of the nasopharynx and sphenoid sinus.

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