Transverse-longitudinal structure registration and vibration measurement via optical coherence tomography.

Intra-organ of Corti displacement measurements made via optical coherence tomography have provided significant information about cochlear micromechanics in recent years. However, several limitations inherent to this modality have complicated interpretation of these measurements. For one, optical coherence tomography measures the one-dimensional projection onto the optical axis of a three-dimensional motion. Also, the optical axis may make a substantial angle with the basilar membrane normal, meaning that structures along the optic axis, measured in a single measurement, may lie in different tonotopic cross-sections. We have developed a method that accounts for both of these complications, to reconstruct the two-dimensional longitudinal-transverse components of displacements of structures within the organ of Corti. This is performed by taking data at multiple longitudinal positions at two viewing angles, without any a priori knowledge of the measurement locations or viewing angles. We present a sample data set in which we have applied this program to reconstruct the transverse-longitudinal motion in the outer hair cell region in the base of the sensitive gerbil cochlea. The results reinforce the importance of accounting for viewing angle when analyzing and reporting vibration results. [ABSTRACT FROM AUTHOR]