Validating a New Tablet-based Tool in the Determination of Cochlear Implant Angular Insertion Depth.

Abstract

The objective of this study is to determine the reliability of a new tablet-based software that utilizes postoperative computed tomography to determine angular insertion depth (AID), cochlear duct length (CDL), and the cochlear place frequency of individual electrodes in cochlear implant recipients. Twenty adult cochlear implant recipients with lateral-wall electrode arrays of varying lengths were included in the study. Cochlear and electrode array measurements were made by 2 otolaryngologists using a tablet-based software. The user manually identifies the modiolus, round window, and each electrode contact to calculate AID. The user also manually identifies cochlear landmarks to calculate the CDL. The AID and CDL are applied to the Greenwood function to obtain an estimate of the cochlear place frequency for each electrode. The primary outcome measure was the reliability of the instrument, as assessed with intra and interrater reliability of measured AID and CDL. The resultant differences in the estimated cochlear place frequency of the most apical electrode were also evaluated. A broad range of AIDs were observed (390°-659°). Intraclass correlation coefficients for intra (0.991) and interrater reliability (0.980) of AID of the most apical electrode contact were excellent. Intra (0.820) and interrater reliability (0.784) of CDL were also excellent. The estimated cochlear place frequency for the most apical electrode differed by an average of 6.7% (0-18.7%) across the 2 raters. There is excellent agreement amongst clinicians in the determination of AID and CDL, resulting in small changes in estimated cochlear place frequency of the most apical electrode using this new software.