Visualization of Maculae and Membranous Semicircular Ducts in the Otic Capsule by Optical Coherence Tomography

Abstract

Objectives:

(1) Show the possibility of using optical coherence tomography (OCT) to visualize the internal structure of the vestibule and semicircular canals with the bony capsule intact. (2) Study the effect of the decalcification. OCT is a nondestructive imaging modality that uses infrared light as it penetrates turbid biological tissue. Previously, OCT has been successfully used to visualize inside the cochlea in normal and abnormal inner ears.

Methods:

The OCT system, OCS-1300SS (Thorlabs, Inc, NJ) with a central wavelength of 1300 nm and a theoretical axial resolution of 9 µm, was employed for image acquisition. Normal and Slc26a4 mutant mice were used as experimental animals. Inner ears were isolated and fixed with 4% paraformaldehyde. Samples were scanned before and after decalcification with 10% ethylenediaminetetraacetic acid for 7 days.

Results:

The saccular and utricular maculae and membranous semicircular ducts were delineated with OCT before and after decalcification. Image quality and imaging depth was better after the decalcification. Signals from the otolith were well observed before decalcification. Normal and pathologically dilated endolymphatic ducts in the bony canal in the knock-out mice were also visualized.

Conclusions:

OCT have the potential to visualize maculae, membranous semicircular ducts, and the endolymphatic duct through the bony capsule. It may also provide new strategy to evaluate the pathology of otolith.