Can a Cochlear Implant Be Used as an Electrical Impedance Tomography Device?

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Otolaryngology

Background:

• Imaging the live cochlea presents significant challenges, with internal structures often obscured by current clinical methods.
• Electrical impedance tomography (EIT) is a safe, low-cost imaging technique with broad clinical potential.
• Accurate visualization of cochlear structures is crucial for evaluating cochlear implant outcomes.

Purpose of the Study:

• To investigate the efficacy of EIT for in vivo imaging of the cochlea.
• To assess EIT's ability to extract the center of gravity (CoG) of the modiolus.
• To evaluate EIT as an augmentation for existing postoperative cochlear imaging techniques.

Main Methods:

• Simulated a cochlear implant EIT system with user-specific electrode array trajectories in a conductive medium.
• Employed an adapted adjacent stimulation protocol for data acquisition.
• Utilized NOSER and Tikhonov priors for image reconstruction, including parameter analysis and validation across noise levels and trajectories.

Main Results:

• The NOSER prior demonstrated superior performance in localizing the modiolus's CoG compared to the Tikhonov prior.
• EIT image reconstruction using NOSER achieved an average CoG localization error below 4% (difference imaging) and 5.5% (absolute imaging).
• Performance remained robust across various noise levels and electrode array trajectories.

Conclusions:

• EIT is a promising technique for in vivo cochlear imaging and modiolus localization.
• The NOSER prior offers enhanced accuracy for cochlear implant EIT applications.
• EIT has the potential to improve postoperative assessment and understanding of cochlear structures.