Mapping Large Strains in Phase-Sensitive OCT: Key Role of Supra-Pixel Displacement Tracking in Incremental Strain Evaluation

Displacement tracking is an important step in realization of compression optical coherence elastography (C-OCE), especially the context obtaining nonlinear stress-strain dependences and subsequent evaluation tissue Young’s modulus. The rapidly progressing phase-sensitive C-OCE, however, enables direct measurements only rather small interframe strains (below 1%), for which displacements are also small. Obtaining curves larger (~10% greater) C-OCE can be made via cumulation particle displacements. resultant values so-found cumulative may significantly exceed pixel size, whereas phase variations usually performed by comparing signals from same a series compared scans. When particles acquired scans reach supra-pixel values, simple pixel-to-pixel estimation lead to significant errors evaluating linear elastic properties tissues. Thus, large strains, adequate accounting order several pixels greater key importance undistorted mapping heterogeneous materials, as well correct boundaries separating regions with different properties. In this paper we discuss elastographic procedures give real examples demonstrating such displacement reconstruction two-dimensional maps biological tissues .