Quantitative methods for reconstructing tissue biomechanical properties in optical coherence elastography: a comparison study

Abstract

We present a systematic analysis of the accuracy of five different methods for extracting the biomechanical properties of soft samples using optical coherence elastography (OCE). OCE is an emerging noninvasive technique, which allows assessing biomechanical properties of tissues with a micrometer spatial resolution. However, in order to accurately extract biomechanical properties from OCE measurements, application of proper mechanical model is required. In this study, we utilize tissue-mimicking phantoms with controlled elastic properties and investigate the feasibilities of four available methods for reconstructing elasticity (Young’s modulus) based on OCE measurements of an air-pulse induced elastic wave. The approaches are based on the shear wave equation (SWE), the surface wave equation (SuWE), Rayleigh-Lamb frequency equation (RLFE), and finite element method (FEM), Elasticity values were compared with uniaxial mechanical testing. The results show that the RLFE and the FEM are more robust in quantitatively assessing elasticity than the other simplified models. This study provides a foundation and reference for reconstructing the biomechanical properties of tissues from OCE data, which is important for the further development of noninvasive elastography methods.

Assessing mechanical properties of tissue phantoms with non-contact optical coherence elastography and Michelson interferometric vibrometry

“…3(b)) was somewhat similar to the displacements detected by the OCE system in this work ( Fig. 3(a)) and previous work [23,40]. The differences in the shape of the temporal profiles can be attributed to the different ways of each technique measure the J of Biomedical Photonics & Eng 1 (4) 1 Feb 2016 © SSAU 234 Fig.…”

“…However, this is in agreement with our very recent investigation and can be explained by assumptions about sample geometry in Eq. 2 and the non-linearity of the agar stress-strain curve [23].…”

“…The elastic wave velocity, c, was then obtained by the inverse slope of the linear fit of the propagation distances, Δd, to the elastic wave propagation delays, Δt [42]. Since the tissue-mimicking agar phantoms can be treated as an isotropic homogeneous elastic material, the Young's modulus [43], E, was estimated by [23,40,44]:…”

“…For all experiments, the output pressure of the air-pulse was ≤ 10 Pa. Uniaxial mechanical compression testing (model 5943, Instron Inc., MA, USA) was performed on the same samples after OCE and LMIV measurement [23]. Figure 3 shows typical 1% agar phantom surface response signal to the air-pulse at various positions during OCE (Fig.…”

“…We have previously utilized the superior displacement sensitivity of OCT to analyze the propagation of a low amplitude (≤ 10 µm) focused airpulse induced elastic wave [21]. By quantifying the velocity, the Young's modulus can then be estimated with reasonable accuracy as compared to uniaxial mechanical testing [22,23].…”