Post-operative evaluation of computed tomography imaging following cochlear implantation

Purpose: This study utilized an automated segmentation algorithm to assess the cochlear implant electrode array within the cochlea and investigate its impact on audiologic outcomes as measured by post-operative speech perception scores. Furthermore, manual evaluations of electrode placement were compared to automatic segmentation methods to determine their accuracy in predicting post-operative audiologic outcomes.Materials and methods: This retrospective chart review was conducted at a tertiary care referral center involving adult post-lingually deafened cochlear implant recipients implanted from 2015 to 2019. Patients with appropriate postoperative imaging and speech testing were included. Patients were excluded if non-English speaking, had a cognitive deficit, or a labyrinthine malformation. Automated and manual methods were used to analyze computed tomography (CT) scans and correlate the findings with post-operative speech perception scores and detection of electrode translocation.Results: Among the 47 patients who met inclusion criteria, 15 had electrode translocations confirmed by automatic segmentation methods. Controlling for CI usage and pre-operative AzBio scores, patients with translocation exhibited significantly lower consonant-nucleus consonant (CNC) and AzBio scores at 6-months post-implantation compared to patients with ST insertions. Moreover, the number of translocated electrode contacts was significantly associated with post-operative CNC scores. Manual evaluations of electrode location were predictive but less sensitive to electrode translocations when compared with automated 3D segmentation. Conclusions: Placement of CI electrode contacts within ST without translocation into SV, leads to improved audiologic outcomes. Manual assessment of electrode placement via temporal bone CT, without 3D reconstruction, provides a less sensitive method to determine electrode placement than automated methods. Level of evidence: Level 4. Lay summary: This study investigated the impact of electrode placement on speech outcomes for cochlear implant recipients. Using advanced imaging techniques, the researchers compared automated and manual methods for evaluating electrode position and examined the relationship between electrode translocation and audiologic outcomes. The findings revealed that proper placement within the cochlea without translocation into inappropriate compartments inside the cochlea improves speech understanding. Manual evaluations were somewhat accurate but less sensitive in detecting translocations compared to automated methods, which offer more precise predictions of patient outcomes. These results contribute to our understanding of factors influencing cochlear implant success and highlight the importance of optimizing electrode placement for improved speech outcomes.