Two-dimensional estimation technique for doppler optical coherence tomography (oct)

Abstract

Optical Coherence Tomography (OCT) is a high-resolution, non-invasive technique to image subsurface tissue and tissue functions. A broadband light source illuminates an object and the reflected photons are processed using an interferometer, demodulated into inphase and quadrature components and then digitized. The captured data contains information about the velocity of the moving scatterers but current Doppler estimation algorithms have a limited velocity detection range. Using a two dimensional velocity estimation, Doppler OCT (DOCT) can be used for the detection of in vivo aortic blood flow rates of over 1 m/s peak velocity through an esophageal DOCT probe. Previous methods have used a transverse Kasai (TK) autocorrelation estimation to estimate the velocity which is good for slow velocities, such as in the microvasculature. By calculating the Kasai autocorrelation with a lag in the depth or axial direction, backscattered frequency information is obtained which yields high velocity rate information. Through subtraction with stationary backscattered information, the Doppler shift is obtained by the axial Kasai (AK) technique. Through utilizing information from two dimensions, velocities can be resolved which spans rates from the microcirculation to cardiac blood flow velocities.