Elasticity and Viscoelasticity Imaging Based on Small Particles Exposed to External Forces

Particle-mediated elasticity/viscoelasticity imaging has the potential to expand the elasticity imaging field, as it can provide accurate and local tissue elastic properties as well as density and viscosity. Here, we investigated elasticity imaging based on small particles located within the tissue and at the tissue interface exposed to static/dynamic external loads. First, we discuss elasticity/viscoelasticity imaging methods based on the use of particles (bubbles and rigid spheres) placed within the tissue. Elasticity/viscoelasticity imaging techniques based on the use of particles (bubbles, rigid, and soft spheres) located at the tissue interface are then presented. Based on new advances, we updated some of the models for the responses of the particles placed within the tissue and at the tissue interface available in the literature. Finally, we compared the mathematical models for the particles located within the tissue and at the tissue interface and evaluated the elasticity/viscoelasticity imaging methods based on the use of small particles. This review summarized the methods for measuring the elasticity and viscosity of material using particles exposed to external forces. Remote viscoelasticity imaging can be used to improve material characterization in both medical and industrial applications and will have a direct impact on our understanding of tissue properties or material defects.