Manifestations of nonlinear elasticity of biological tissues in compressional optical coherence elastography

We discuss the application of compressional OCT-based elastography for measuring elastic response of biological tissues in the strain range from fractions of one per cent up to strains over similar to 10% and greater. Such fairly large strains are not typical of phase-sensitive OCT-based elastographic methods and can be measurable due to application of interframe strain-estimation method in which interframe phase gradients are estimated without the necessity of preliminary measuring total displacements of scattering particles in combination with summation of interframe strains. For estimating applied stresses, intervenient soft layer of translucent silicone is used a a reference fairly linear material. The obtained results based on comparison of strains in the reference layer and tissue demonstrate highly nonlinear character of elasticity of biological tissues even for rather moderate strains on order of several per cent.