Angular Insertion Depth for Cochlear Implantation: A Comparative Analysis on Precision of CT, MRI, and x-Ray

Personalized medicine in cochlear implantation has advanced significantly with the advent of software tools that allow for detailed analysis of cochlear anatomy. This facilitates the selection of electrode arrays tailored to the individual cochlear duct length (CDL) and supports anatomy-based fitting strategies. Concurrently, various imaging modalities-both preoperatively and postoperatively-can be assessed in a plug-and-play manner. However, to date, no study has performed a direct, systematic comparison of all commonly used imaging modalities preoperative and postoperative computer tomography (CT), magnetic resonance imaging (MRI), and x-ray.

Retrospective study.

Tertiary Referral Center.

In total, 31 cochlear implantations with preoperative high-resolution CT and MRI, and postoperative high-resolution CT were analyzed with the software OTOPLAN, as well as manual measures from Stenvers view x-ray. Cochlear anatomy values derived from the different modalities were compared and correlated.

Postoperative CT and x-ray showed excellent correlation for angular insertion depth across all electrode contacts. In contrast, apical contact values for both preoperative CT and MRI deviated significantly from those derived from postoperative CT scans.

This study is the first to directly correlate intracochlear electrode position estimates obtained from these four imaging modalities and observed a high correlation between postoperative CT and x-ray measurements across all electrode contacts. In contrast, notable variations were observed when comparing these postoperative results with preoperative imaging data. These findings highlight the potential of postoperative x-ray-based analysis as a feasible and efficient method for anatomy-based fitting, supporting its integration into routine clinical workflows.