Micro-computed Tomography Validation of Cochlear Implant Electrode Position

Abstract

Introduction Cochlear implant (CI) electrode position is a key determinant of postoperative auditory outcomes. Existing computed tomography (CT)-derived metrics of postoperative electrode position are inconsistently defined and poorly validated. Aims 1. Evaluate the existing literature regarding the validity of CT-derived metrics of CI electrode position. 2. Validate the accuracy and reproducibility of clinical CT-derived intracochlear electrode position metrics against microCT in implanted cadaveric temporal bones. Methods Chapter 1 systematically reviews the literature validating CT-derived metrics of intracochlear electrode position against reference standards. Chapter 2 reports a cadaveric temporal bone validation study in which implanted cadaveric temporal bones were imaged using multidetector CT (MDCT), cone-beam CT (CBCT), and micro-computed tomography (microCT). Whole array and electrode contact-level metrics were measured. Inter-modality agreement and interobserver reliability were assessed. Results Validation of existing CT-derived intracochlear electrode position metrics is limited and heterogenous. Intracochlear position metrics derived from clinical CT showed close agreement the radiological gold standard. CBCT showed consistently closer agreement with microCT than MDCT across most whole array and electrode contact-level metrics. Interobserver reliability was good to excellent for most metrics, particularly as measured on CBCT. Conclusion Clinical CT can accurately quantify intracochlear electrode position. CBCT shows the closest agreement with a radiological reference standard with high interobserver reliability. Whole array-level metrics show strong agreement across imaging modalities. Electrode contact–level metrics are reliably represented on CBCT but constrained on MDCT by spatial resolution and metal artefact. These findings establish clinical CT, particularly CBCT, as a reliable tool for postoperative CI electrode assessment.