Objective

The purpose of this study was to use high-speed optical coherence tomography (OCT) to obtain cross-sectional images of the rat cochlea.

Study design and methods

The cochleae of Sprague- Dawley rats were imaged within 2 to 4 hours after death. Specimens were prepared by removing the bulla to expose the mesotympanum; some images were obtained in intact temporal bones removed from the cranium. The central element of an OCT imaging device is a Michelson interferometer combined with a low-coherence light source. This study used 2 OCT systems with different light sources: 1) a semiconductor optical amplifier operating and 2) a superluminescent diode with peak emissions wavelengths of 1.3 microm and 827 nm, respectively. Images (1.87 x 2.00 mm or 1.87 x 1.00 mm, 10 x 10 microm pixel resolution) were acquired at a frame rate of 1 Hz. Cross-sectional images at 100-microm increments were obtained from a medial-to-lateral direction.

Results

The scala vestibuli, scala media, scala tympani, modiolus, spiral ligament, and several turns of the cochlea were identified.

Conclusion

These images reflect the ability of OCT to provide images of the internal cochlea structure with micron scale resolution and at near-real time frame rates.