Optical coherence tomography (OCT) is a contactless and non-invasive imaging technique. Due to the high resolution of some 10 μm and the penetration depth of 1-2 mm in scattering tissue, OCT closes the gap between microscopy and sonography. Here, we present a GRIN-based endoscopic OCT (eOCT) system for middle ear diagnostics. EOCT combines the benefit of endoscopic imaging and the advantage of morphological and functional investigation of the tympanic membrane (TM). The eOCT system has a working distance of 10 mm, which results in a field-of-view of 10 mm. This allows a full three-dimensional visualization of the TM and surrounding tissue. In addition, the oscillation of the TM can be measured spatially resolved and in the frequency range between 500 Hz and 5000 Hz with 125 Hz resolution, which is realized by phase-resolved Doppler-OCT. First clinical results are demonstrated for one selected cases, a middle ear effusion.
An endoscopic optical coherence tomography (OCT) system with a wide field-of-view of 8 mm is presented, which combines the image capability of endoscopic imaging at the middle ear with the advantages of functional OCT imaging, allowing a morphological and functional assessment of the human tympanic membrane. The endoscopic tube has a diameter of 3.5 mm and contains gradient-index optics for simultaneous forward-viewing OCT and video endoscopy. The endoscope allows the three-dimensional visualization of nearly the entire tympanic membrane. In addition, the oscillation of the tympanic membrane is measured spatially resolved and in the frequency range between 500 Hz and 5 kHz with 125 Hz resolution, which is realized by phase-resolved Doppler OCT imaging during acoustical excitation with chirp signals. The applicability of the OCT system is demonstrated in vivo. Due to the fast image acquisition, structural and functional measurements are only slightly affected by motion artifacts.