Measurement of Cochlear Dimensions Using the Transimpedance Matrix

This is the authors' abstract. We don't add key points for this paper.

OBJECTIVE: Transimpedance matrix (TIM) measurements can not only detect abnormal electrode positioning in patients with cochlear implants (CI) but also estimate the angular insertion depth (AID). This study aims to assess the feasibility of using TIM to measure cochlear morphology-specifically its dimensions and electrode position-and to identify electrode pairs best associated with these dimensions. STUDY DESIGN: Retrospective cohort study. SETTING: University Medical Center, tertiary academic referral center. PATIENTS: Patients undergoing CI (CI622) surgery between January 2020 and April 2024. INTERVENTION: Cochlear size parameters, including diameter, width, height, and cochlear duct length (CDL), were obtained preoperatively from CT imaging using OTOPLAN. The maximal angular insertion depth (maxAID) was determined from x-ray imaging based on Stenvers' projection. Gradient phases between electrode pairs and heatmaps were extracted from TIM data. Pearson correlation analysis was conducted to examine the relationships between cochlear size parameters and TIM data. MAIN OUTCOME MEASURES: Out of 41 patients, 39 were included in this study. A significant positive correlation was found between the maxAID and the gradient phase of electrode pairs E20-E10 (R = 0.798, P < 0.0001). Negative correlations between cochlear size and gradient phase were identified: (1) diameter: R = -0.59, P < 0.05 (E18-E11), (2) width: R = -0.609, P < 0.05 (E16-E4), (3) height: R = -0.634, P < 0.01 (E8-E22), (4) cochlear duct length (CDL) R = -0.634, P < 0.01 (E16-E12). CONCLUSIONS: TIM measurements are useful for assessing cochlear dimensions.