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Updated: Jan 7, 2026
Enhancing Electrode Location Assessment in Cochlear Implantation via Computed Tomography Image Fusion
Published on: January 17, 2025
Systematic Overestimation of the Angular Insertion Depth of Electrode Arrays in Cochlear Implantation (CI) Patients
Florian Herrmann Schmidt1, Lichun Zhang1, Mats Wilhelm Glabasnia1
1Department of Otorhinolaryngology, Head and Neck surgery, 'Otto Körner', Rostock University Medical Center, Rostock, Germany.
Objective:
By estimating the length of the cochlear duct, commercial software algorithms intend to support CI teams by the selection of the suitable electrode array length prior to cochlear implant (CI) surgery. In the present study center, predominantly 31.5 mm flexible electrode arrays are used for patients with radiologically regular cochleae. Routinely performed postoperative Stenvers x-ray detects complete insertion in all cases. The aim of this study was to test the accuracy of the commercial software algorithm in predicting the angular insertion depths for this specific CI group with deeply inserted electrodes.
Study Design:
Retrospective cohort study.
Setting:
University medical center, tertiary academic referral center.
Patients:
Patients undergoing a cochlear implant surgery MED-EL FLEXsoft electrode array (Synchrony2, MED-EL, Innsbruck, Austria) between January 2019 and December 2022.
Intervention:
Preoperative CT images for 72 CI ears with 31.5 mm flexible electrode arrays were examined using OTOPLAN, and the maximum insertion depth (maxAID) was estimated. Postoperatively, the actual maxAID was determined through Stenvers x-ray images.
Main Outcome Measures:
The preoperatively estimated maxAID demonstrated a correlation with the postoperatively measured maxAID (R = 0.45, p < 0.001) but deviated by 44.8° ± 8.4°. There is a systematic overestimation by OTOPLAN of the insertion depths for estimated values exceeding 720°. To address this, an optimal offset of 2.4 mm is identified when considering this parameter in estimating maxAID for depths exceeding 720°.
Conclusion:
OTOPLAN predicts AID outcomes in CI patients but may deviate in small cochleae (CDL < 35 mm).
