Quantitative Ultrasound: Scattering Theory.

The radio-frequency ultrasound backscattered data from tissue is rich in information and can provide important information about tissue state that is not obtained through traditional B-mode imaging. To parameterize the ultrasound backscattered data, the frequency spectrum, i.e., the backscatter coefficient, can be modeled using scattering theory. Models of tissue scattering are often represented by simple discrete geometric shapes, i.e., discrete scattering model. The discrete scattering model provides important insights into how the spatial arrangement of scatterers contributes to the signal spectrum. Another competing model is the continuum scattering model. In this model, the tissue is described as a continuous tissue construct with scatterers that have a continuous impedance change from the background. The continuous model provides a form factor description of the underlying tissue scatterers such as an effective scatterer diameter. In this chapter, we will compare and contrast the two underlying tissue scattering models and how they provide insights into ultrasonic scattering from soft tissues.