Local Spectral Nonlinear Elasticity Imaging: Contrast Enhancement in Heterogeneous Elastograms based on Viscoelastic Nonlinear Characterizations

Imaging of tissue biomechanical properties like viscosity or nonlinear elasticity provide additional information about tissue composition through its contrast imaging capability. Most nonlinear elasticity imaging techniques consider group shear wave speed (SWS) changes with stress to determine the elastic nonlinearity. However, due to viscosity tissue exhibits dispersive behavior and SWS changes with frequency. Consequently, nonlinear elastic parameters change with excitation frequency. This change in nonlinear elasticity with excitation frequency is different for different tissues types. Imaging of local spectral nonlinear elastic properties could provide additional contrast compared to group shear velocity based nonlinear elastograms and help in early diagnosis.