Vector method of strain estimation in OCT-elastography with adaptive choice of scale for estimating interframe phase-variation gradients

Abstract

Abstract In this paper we present a method which significantly improves strain-estimation quality in phase-sensitive optical coherence elastography (OCE). Specifically, we consider the realization of phase-sensitive OCE termed ‘vector method’, among main advantages of which are its high computational efficiency and high robustness with respect to measurement noises. The method does not require any search operations, but the quality of local strain estimation heavily depends on the quality of numerical spatial differentiation of inter-frame phase variations. This differentiation does not require phase unwrapping even for supra-wavelength displacements of scatterers, but the differentiation results depend on the chosen scale for phase-gradient estimation. Either too small or too large scale may strongly degrade the results of elastographic visualization, especially in the presence of pronounced spatio-temporal strain inhomogeneity. The proposed adaptive automatic choice of the differentiation scale complements earlier proposed vector averaging and significantly improves strain-mapping quality in OCE. The method efficiency is demonstrated using both numerically simulated and real OCT scans.