Optical Coherence Tomography for Clinical Otology

Dan MacDougall, Thomas Landry, Manohar Bance, Jeremy Brown, Robert Adamson

Abstract


Optical Coherence Tomography (OCT) is an interferometric imaging technique used to produce high-resolution depth-resolved images in tissue. By probing tissue with light, tissue morphology can be determined from the characteristics of an interference pattern produced by any light that is backscattered by sub-surface structures. OCT can be thought of as the optical analog to ultrasound.

The middle ear is a unique part of the human body that is well-suited to diagnostic imaging using OCT. The eardrum, located at the end of the external ear canal, drives the bony ossicular chain (malleus, incus, stapes) to conduct sound to the inner ear.  The eardrum is thin (approx. 100-300 microns) and translucent and so is easily penetrated by infrared light. OCT provides a window into the middle ear that could allow diagnostic capabilities unlike other technologies currently available in otology. While the potential for otological OCT has been recognized for several years, it has yet to be adapted into a form suitable for clinical practice. OCT’s ability to measure both structure and physical dynamics using Doppler detection points towards a system with tremendous diagnostic capabilities in the middle ear, particularly in the diagnosis of conductive hearing losses.

We demonstrate a real-time OCT imaging system designed specifically for use in clinical middle ear imaging. The system is a custom-built swept-source OCT system that makes use of an akinetic tunable laser (Insight Photonic Solutions, Inc.) and optics designed for imaging live patients. Real-time signal processing is achieved on a graphics-processing-unit (GPU), including simultaneous structural imaging and Doppler vibrometric functional imaging, and has been integrated into a GUI for use by clinicians. We present our system in its final design stages as we prepare to deploy it for clinical trials. Images acquired in cadaveric human temporal bones and human volunteers will be presented.


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