Introduction:
Optical Coherence Tomography (OCT) allows non-invasive high-resolution imaging of
tissues. With a penetration depth of a few millimeters it's possible to image the
tympanic membrane and the close-by part of the tympanum, e.g. for diagnostics of otitis
media and middle ear effusion. In the field of in vivo examination there are difficulties
in access to the human tympanic membrane due to the narrow and curved external ear
canal. We report a compact endoscopic OCT system for use in clinical research.
Methods:
We use a 3,5 mm endoscopic GRIN lens for video endoscopy and OCT. OCT is conducted
via an adjustable laser with a spectral range around 1300nm. Working distance and
field-of-view are 8 mm, respectively. The system was evaluated with ten subjects without
ear disease. The three-dimensional structure and the oscillation of the tympanic membrane
were examined. Data were compared to preliminary studies on temporal bone specimens.
Results:
The average examination time was 4 minutes. Imaging of tympanic membrane was possible.
Despite there are visible motion artifacts, 3D-images were comparable to preliminary
studies on temporal bones. Functional measurement produced comparable results, too.
Conclusion:
Our endoscopic OCT system allows high-resolution morphologic and functional examination
of the human tympanic membrane. The wide field-of-view and the spatially and frequency
resolved vibrometry with a recording time of less than ten seconds obtain an advantage
over microscope and otoscope-based OCT systems.
