Acousto-elasticity of transversely isotropic incompressible soft tissues: characterization of skeletal striated muscle

• Published in: Physics in medicine & biology Vol. 66; no. 14; pp. 145009 - 145022
• Main Authors: Remeniéras, Jean-Pierre, Bulot, Mahé, Gennisson, Jean-Luc, Patat, Frédéric, Destrade, Michel, Bacle, Guillaume
• Format: Journal Article
• Language: English
• Published: England IOP Publishing 21.07.2021
• Subjects: acousto-elasticity; Biomechanics; Elastic Modulus; Elasticity; Elasticity Imaging Techniques; Humans; maximum voluntary contraction; Mechanics; Medical Physics; Muscle, Skeletal - diagnostic imaging; musculoskeletal disorders; Physics; shear wave elastography; third order elastic constants; transversely isotropic soft solid; acousto-elasticity; third order elastic constants; musculoskeletal disorders; transversely isotropic soft solid; maximum voluntary contraction; shear wave elastography; Musculoskeletal disorders; Transversely Isotropic soft solid; Maximum Voluntary Contraction; Shear Wave Elastography; Acousto-elasticity; Third order elastic constants
• ISSN: 0031-9155; 1361-6560; 1361-6560
• DOI: 10.1088/1361-6560/ac0f9b

Using shear wave elastography, we measure the changes in the wave speed with the stress produced by a striated muscle during isometric voluntary contraction. To isolate the behaviour of an individual muscle from complementary or antagonistic actions of adjacent muscles, we select the muscle, whose sole function is to extend the little finger. To link the wave speed to the stiffness, we develop an acousto-elastic theory for shear waves in homogeneous, transversely isotropic, incompressible solids subject to an uniaxial stress. We then provide measurements of the apparent shear elastic modulus along, and transversely to, the fibre axis for six healthy human volunteers of different age and sex. The results display a great variety across the six subjects. We find that the slope of the apparent shear elastic modulus along the fibre direction changes inversely to the maximum voluntary contraction (MVC) produced by the volunteer. We propose an interpretation of our results by introducing the S (slow) or F (fast) nature of the fibres, which harden the muscle differently and accordingly, produce different MVCs. A natural follow-up on this study is to apply the method to patients with musculoskeletal disorders or neurodegenerative diseases.