Improved Middle Ear Imaging with Optical Coherence Tomography for Clinical Otology

Abstract

Conductive hearing loss (CHL) is a widespread and debilitating condition that affects millions of individuals worldwide. This impairment results from disruptions in the transmission of sound waves from the tympanic membrane (TM) to the inner ear. Unfortunately, existing diagnostic tools are often inadequate in pinpointing the root causes of CHL, leading to uncertainty when determining the most appropriate clinical management plans. Optical coherence tomography (OCT) is an emerging imaging modality that offers non-invasive, high-resolution structural images of the middle ear. It also allows for measuring vibrations in middle ear structures in response to sound through an intact TM. Like all biomedical imaging methods, middle ear OCT (ME-OCT) aims to extract diagnostically significant information from the acquired images. However, its clinical application is limited by suboptimal image quality, due in large part to sidelobe artefacts and the effective imaging depth in the presence of optically opaque structures, such as cartilage tympanoplasty. This thesis introduces two approaches to improve middle ear visualisation using OCT without modifying the existing imaging system. First, it presents a method that employs a convolutional basis pursuit framework to eliminate imaging artefacts related to strong reflections at tissue-air interfaces, which impede accurate morphology-based diagnoses. Second, it explores the potential of an optical clearing agent using a topical glycerol treatment to increase the transparency of cartilage grafts, allowing for OCT visualisation of the post-operative middle ear. The enhanced image quality could facilitate more precise CHL diagnoses based on morphological changes of middle structures, providing clinicians with more accurate and reliable diagnostics using ME-OCT.