Assessing MRI Interpretability of the Orbit, Paranasal Sinuses, and Nasopharynx in Cochlear Implant Patients

Manuel Christoph Ketterer^1*Philipp Arnold¹Antje Aschendorff¹Stefan Granitzer²Michael Reich¹Ann-Kathrin Rauch¹Tanja Hildenbrand¹Susan Arndt¹Leonie Fries¹

• ¹University of Freiburg, Freiburg, Germany
• ²Oticon Medical, France, France

Objectives: Due to a growing focus on cost-effectiveness in healthcare, safety concerns with CI and the known limitations in image quality, there is an increasing need for well-considered indications before performing magnetic resonance imaging (MRI) in CI (cochlear implant) patients. This study aims to evaluate, for the first time, the clinical utility and limitations of MRI in CI patients for orbital, paranasal, and nasopharyngeal assessments. Materials and Methods: CIs were positioned and fixed with bandaging around the head of a test subject at varying angular positions (90°, 120°, and 135°), both unilaterally and bilaterally, with and without the magnet in place. MRI acquisitions included T1-MP-RAGE, T2-TSE, T1-TIRM, and DWI sequences of a 3 Tesla MRI scanner. The MRI images were reconstructed three-dimensionally, and the resulting artifacts were analyzed to determine the interpretability of the predefined orbital, paranasal, and nasopharyngeal structures. Results: Image quality was categorized into four levels of restriction. It was observed that orbital MRI diagnostics in the required sequences (T1, T2, and DWI) are feasible even in patients with bilateral CIs with magnets in situ. Regarding the paranasal sinuses, artifacts affected the sphenoid sinus and parts of the ethmoidal cells; however, as expected, the interpretability improved significantly without the magnet. The nasopharyngeal space, particularly in patients with bilateral CIs and magnets in situ, could be evaluated only with difficulty or was largely not assessable. Conclusion: This study offers insights into the predictive factors influencing the interpretability of MRI scans for the orbit, paranasal sinuses, and nasopharynx in CI patients. In particular, for the sphenoid sinus and nasopharynx, it is strongly advised to consult the responsible CI center before undergoing an MRI examination. This consultation helps assess the necessity of the MRI and, if required, consider the removal of the implant magnet.