Viscosity and Nonlinear Elastography Will Be the Next Generation Biomarkers in Clinical Diagnosis

Abstract

Elastic changes in a tissue are associated with a broad spectrum of pathologies, which stems from the tissue microstructure, histology and biochemistry. This presentation aims to elucidate the potential of viscous and nonlinear elastic parameters as conceivable diagnostic mechanical biomarkers. First, by providing an insight into the role of soft tissue microstructure in linear elasticity; second, by understanding how viscosity and nonlinearity could enhance the current diagnosis in elastography; and finally, by compounding preliminary investigations of those elastography parameters within different technologies. Ultrasonic elastography characterization and understanding of soft tissue is recently being developed as a clinical diagnostic tool. New elastography sensor technologies, from hardware to algorithms, are bound to endow a new class of biomarkers that quantify the mechanical functionality and abnormalities in the structural architecture of soft tissues are intimately linked to a broad range of pathologies including tumors, atherosclerosis, ageing, liver fibrosis or osteoarticular syndromes, to name a few. These higher order mechanical parameters may become key discriminating biomarkers since: (1) the physics of wave propagation is explaining how dispersion is a compound expression of the rheological, poroelastic, and microstructural scattering and (2) the extreme hyperelasticity that soft tissue exhibits clearly manifests as quantifiable harmonic generation.