Imaging the Human Tympanic Membrane Using Optical Coherence Tomography In Vivo

Abstract

Objective-Optical coherence tomography (OCT) is a diagnostic imaging modality that combines low coherence light with inter ferometry to produce high-resolution cross-sectional images of living tissues. Using this technology, we have imaged in vivo the human tympanic membrane (TM) in the office clinic setting and characterized TM microstructure in normal and pathologic conditions. Study Design-Prospective clinical trial.Materials and Methods-The normal and diseased TMs in 10 adult subjects were examined. Each subject underwent direct microscopic examination before OCT imaging to provide visual coregistration of associated subsites including the anulus fibrosus, pars tensa, pars flaccida, and umbo. The probe from the imaging system (1,310-nm central wavelength, 15-μm coherence length, Niris; Imalux, Cleveland, OH, USA) was introduced into the ear canal to obtain lateral cross-sectional images.Results-Systematic imaging of the TM was performed with characterization of the epithelial and collagenous layers. The overall TM thickness was clearly demonstrated and quantified.Conclusion-The ability to noninvasively study middle ear microstructures in vivo is essential in the treatment of diseases of the ear. OCT may provide the otologist/neurotologist with the ability to 1) image pathology such as cholesteatoma, dimeric TMs, and chronic otitis media; 2) gauge the response to pharmacological therapy; and 3) monitor postsurgical changes after tympanoplasty and other procedures. OCT may provide a means to optimize the diagnosis and management of patients with middle ear disease. (1). It uses light to discern differences in tissue microstructure and uses coherence gating to localize the origin of the reflected optic signal. OCT is analogous to B-mode ultrasonography but uses broadband near-infrared light to produce images with a resolution approaching that of light microscopy (10-15 μm) (1,2). OCT relies on differences in tissue optical properties to generate contrast, with axial resolution on the order of 10 μm and of a depth of penetration of approximately 1 to 2 mm, depending on turbidity. Axial resolution is inversely proportional to the coherence length of the sources. Lateral resolution is diffraction limited and therefore dependent on the optical design of each device. Although OCT has been used as a measurement tool in ossiculoplasties and stapedectomies (3), in vivo use of OCT in the human tympanic membrane (TM) has not previously been reported. KeywordsIn the head and neck, OCT applications have primarily focused on characterizing cancer and other disease processes in the larynx (4), because OCT is ideal for imaging the thin, layered structures of the vocal fold epithelium and lamina propria. Most OCT applications in the study of the middle and inner ear have focused on either animal investigations or human temporal bone studies (5-10). In this study, we use OCT to image and characterize the TM in both normal and pathologic conditions. Successful OCT imaging of the TM will allow the clinician to obtain stru...

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Investigation of the human tympanic membrane oscillation ex vivo by Doppler optical coherence tomography

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