Feasibility of reverberant shear wave elastography for in vivo assessment of skeletal muscle viscoelasticity

Quantifying the local stiffness of muscular tissue can be a useful tool for the improvement of diagnosis, treatment or monitoring of muscle abnormality-related diseases. Shear wave elastography techniques provide information about tissue stiffness by measuring the shear wave speed (SWS). Recently, a new framework involving the generation of a reverberant shear wave field that propagates in all directions within the medium was proposed. The aim of this study is to evaluate the feasibility of Reverberant Shear Wave Elastography (R-SWE) for the in vivo assessment of the viscoelastic properties of skeletal muscle, using the biceps brachii. Four experiments were performed at a vibration frequency range between 200-300 Hz in steps of 50 Hz, with the ultrasound transducer placed along the muscle fibers in both relaxed and contracted (MVC) states. The estimation of the SWS and a dispersion analysis using the Kelvin-Voigt Fractional Derivative (KVFD) model were carried out in order to assess the viscoelastic properties of the muscular tissue. Preliminary results show that R-SWE is feasible to use for the in vivo assessment of skeletal muscle by using a multifrequency approach. The viscoelastic parameters obtained by the KVFD curve-fitting and the dispersion analysis showed the expected differences between the relaxed and MVC states (i.e. a significant difference between the coefficient of viscosity and the dispersion rate of change). The SWS estimation also showed differences between the two states (e.g. a difference in SWS values of 35.52% at 300 Hz).