Evaluating tissue mechanical properties using Mueller matrix polarimetry

Abstract

Evaluating tissue mechanical properties is an important issue in the biomedical field. While traditional in vitro tissue deformation experiments have been used to measure mechanical properties, optical methods are becoming increasingly popular due to their non-invasive and non-contact advantages. In this study, we utilized Mueller matrix polarimetry to quantify the mechanical properties of bovine tendon tissue. We acquired 3×3 Mueller matrix images of the tendon tissue samples under various stretching states using a backscattering measurement setup based on a polarization camera, enabling us to examine changes in both structural information and optical properties. Subsequently, we extracted frequency distribution histograms of Mueller matrix elements to elucidate the structural changes in the tendon tissue during the stretching process. We then calculated the Mueller matrix transformation parameters, namely the total anisotropy t1 and anisotropy direction α1 of the tendon tissue samples under different stretching processes, to characterize their structural changes quantitatively. For better discrimination of tendon tissues under different stretching states, we trained an image classification neural network using the derived MMT parameters as input. Ultimately, we obtained a highly accurate model with 90% precision. The results demonstrate the potential of Mueller matrix polarimetry as a tool for evaluating tissue mechanical properties.