Intracochlear Imaging Using IVUS and OFDI: A Cadaveric Feasibility Study.

Objective: This study evaluates the feasibility of optical frequency domain imaging (OFDI) and intravascular ultrasound (IVUS) for intracochlear imaging in human cadaveric specimens. We compare their resolution, depth penetration, and ability to identify key cochlear structures and pathological conditions. Methods: Human cadaveric temporal bones were prepared, and OFDI and IVUS probes were inserted through the round window into the scala tympani. OFDI imaging was performed using the LUNAWAVE system (Terumo, Tokyo, Japan), while IVUS imaging was conducted using the VISICUBE system (Terumo, Tokyo, Japan) with 60 and 40 MHz probes. The probe tips were trimmed to optimize insertion and imaging. Imaging results were compared with histological sections. Results: OFDI provided high-resolution visualization of the cochlear basal turn, allowing clear identification of the basilar membrane, Reissner's membrane, scala media, and the organ of Corti. IVUS exhibited lower resolution than OFDI but allowed for deeper tissue penetration. The 60 MHz IVUS probe provided higher resolution than the 40 MHz probe, while the 40 MHz probe offered a wider field of view due to greater penetration depth and lower attenuation. Both OFDI and IVUS successfully detected basilar membrane disruptions, a known complication in cochlear implant surgery. Conclusion: OFDI and IVUS demonstrated feasibility for intracochlear imaging, with OFDI offering superior resolution and IVUS providing greater penetration. This is the first study to apply IVUS for intracochlear imaging, supporting its potential role in intraoperative monitoring and cochlear pathology assessment. Level of Evidence: N/A.