Quantitative assessment of the mechanical properties of tissue-mimicking agar phantoms by optical coherence elastography and numerical analyses

Abstract

A systematic investigation was conducted on the accuracies of four analytical methods for obtaining the elasticity of soft samples by using optical coherence elastography (OCE). The results were compared to the elasticity measured by uniaxial mechanical testing. OCE has emerged as a noninvasive method for quantifying tissue biomechanical properties with spatial resolution of a few micrometers. A proper mechanical model is required for extracting the biomechanical parameters accurately from OCE measurements. In this work, tissuemimicking agar phantoms were utilized to analyze the accuracy and feasibility of four methods for reconstructing the Young’s modulus from OCE-measured elastic wave which were induced by a focused airpulse. These reconstruction methods are: the shear wave equation (SWE), the surface wave equation (SuWE), the Rayleigh-Lamb frequency equation (RLFE), and the finite element method (FEM). The reconstructed elasticity values were also compared with uniaxial mechanical testing results. It was shown that the RLFE and the FEM are more robust in quantifying elasticity than the other simplified models. This work may provide a reference for reconstructing the biomechanical properties of tissues based on OCE measurements. Accurate reconstruction of biomechanical properties is an important issue for further developing noninvasive elastography methods.