Robust Cochlear Modiolar Axis Detection in CT

Wimmer, Wilhelm; Vandersteen, Clair; Guevara, N.; Caversaccio, Marco; Delingette, Hervé

doi:10.1007/978-3-030-32254-0_1

Cited by 7 publications

(6 citation statements)

References 9 publications

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“…A local coordinate system (Fig. 1 A) was formed ( Verbist et al 2010 ), where a robust cochlear modiolar axis detection algorithm defined the z axis ( Wimmer et al 2019 ). The x axis passed through the landmarks C’ (origin) and RW, where C’ is the orthogonal projection of RW onto the z axis ( Wimmer et al 2014 ).…”

Section: Methodsmentioning

confidence: 99%

Postoperative Impedance-Based Estimation of Cochlear Implant Electrode Insertion Depth

et al. 2023

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Objectives: Reliable determination of cochlear implant electrode positions shows promise for clinical applications, including anatomy-based fitting of audio processors or monitoring of electrode migration during follow-up. Currently, electrode positioning is measured using radiography. The primary objective of this study is to extend and validate an impedance-based method for estimating electrode insertion depths, which could serve as a radiation-free and cost-effective alternative to radiography. The secondary objective is to evaluate the reliability of the estimation method in the postoperative follow-up over several months. Design: The ground truth insertion depths were measured from postoperative computed tomography scans obtained from the records of 56 cases with an identical lateral wall electrode array. For each of these cases, impedance telemetry records were retrieved starting from the day of implantation up to a maximum observation period of 60 mo. Based on these recordings, the linear and angular electrode insertion depths were estimated using a phenomenological model. The estimates obtained were compared with the ground truth values to calculate the accuracy of the model. Results: Analysis of the long-term recordings using a linear mixed-effects model showed that postoperative tissue resistances remained stable throughout the follow-up period, except for the two most basal electrodes, which increased significantly over time (electrode 11: ~10 Ω/year, electrode 12: ~30 Ω/year). Inferred phenomenological models from early and late impedance telemetry recordings were not different. The insertion depth of all electrodes was estimated with an absolute error of 0.9 mm ± 0.6 mm or 22° ± 18° angle (mean ± SD). Conclusions: Insertion depth estimations of the model were reliable over time when comparing two postoperative computed tomography scans of the same ear. Our results confirm that the impedance-based position estimation method can be applied to postoperative impedance telemetry recordings. Future work needs to address extracochlear electrode detection to increase the performance of the method.

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Section: Methodsmentioning

confidence: 99%

Postoperative Impedance-Based Estimation of Cochlear Implant Electrode Insertion Depth

et al. 2023

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“…In accordance with the standard clinical protocol, the patient was bedded in a lateral position with the head in hyperextension. The rotation that transforms the local cochlear coordinate system (according to Verbist et al [43], [44], c. f., Figure 2) to this orientation can be expressed by the Euler angles (α = 90°, β = 52°, γ = −65°).…”

Section: A Experimental Setupmentioning

confidence: 99%

In-Vitro Study of Speed and Alignment Angle in Cochlear Implant Electrode Array Insertions

Aebischer

Mantokoudis

Weder

et al. 2022

IEEE Trans. Biomed. Eng.

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The insertion of the electrode array is a critical step in cochlear implantation. Herein we comprehensively investigate the impact of the alignment angle and feed-forward speed on deep insertions in artificial scala tympani models with accurate macro-anatomy and controlled frictional properties. Methods: Motorized insertions (n=1033) were performed in six scala tympani models with varying speeds and alignment angles. We evaluated reaction forces and micrographs of the insertion process and developed a mathematical model to estimate the normal force distribution along the electrode arrays. Results: Insertions parallel to the cochlear base significantly reduce insertion energies and lead to smoother array movement. Non-constant insertion speeds allow to reduce insertion forces for a fixed total insertion time compared to a constant feed rate. Conclusion: In cochlear implantation, smoothness and peak forces can be reduced with alignment angles parallel to the scala tympani centerline and with non-constant feed-forward speed profiles. Significance: Our results may help to provide clinical guidelines and improve surgical tools for manual and automated cochlear implantation.

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“…al [18]. To reduce uncertainty caused by landmark based modiolus identification, a robust cochlear axis detection algorithm was used [19]. Pre-and postoperative CT images were first cropped, then registered using a normalized mutual information algorithm.…”

Section: Electrode Localization and Insertion Depthmentioning

confidence: 99%

Intraoperative Impedance-Based Estimation of Cochlear Implant Electrode Array Insertion Depth

Aebischer

Meyer

Caversaccio

et al. 2021

IEEE Trans. Biomed. Eng.

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Cochlear implant impedances are influenced by the intracochlear position of the electrodes. Herein, we present an intuitive approach to calculate tissue resistances from transimpedance recordings, ultimately enabling to estimate the insertion depth of cochlear implant electrodes. Methods: Electrode positions were measured in computed-tomography images of 20 subjects implanted with the same lateral wall cochlear implant model. The tissue resistances were estimated from intraoperative telemetry data using bivariate spline extrapolation from the transimpedance recordings. Using a phenomenological model, the electrode insertion depths were estimated. Results: The proposed method enabled the linear insertion depth of all electrodes to be estimated with an average error of 0.76 ± 0.53 mm. Conclusion: Intraoperative telemetry recordings correlate with the linear and angular depth of electrode insertion, enabling estimations with an accuracy that can be useful for clinical applications. Significance: The proposed method can be used to objectively assess surgical outcomes during and after cochlear implantation based on non-invasive and readily available telemetry recordings.

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Robust Cochlear Modiolar Axis Detection in CT

Cited by 7 publications

References 9 publications

Postoperative Impedance-Based Estimation of Cochlear Implant Electrode Insertion Depth

Postoperative Impedance-Based Estimation of Cochlear Implant Electrode Insertion Depth

In-Vitro Study of Speed and Alignment Angle in Cochlear Implant Electrode Array Insertions

Intraoperative Impedance-Based Estimation of Cochlear Implant Electrode Array Insertion Depth

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