Relationship between ultrasound scattering and acoustic impedance maps in sparse and dense random media

Abstract

Quantitative modeling of ultrasound scattering from soft tissues has been used extensively to characterize soft tissues. In this approach, tissues are typically modeled as a random medium containing scatterers of specific shapes, acoustic properties, and spatial arrangements. Under plane-wave insonification and assuming weak scattering (i.e., Born approximation), the backscattered coefficient (BSC) of such a random medium is fully described by the power spectrum of its three-dimensional (3D) impedance map (ZM). A two-dimensional (2D) ZM can be obtained by scanning acoustic microscopy (SAM) applied to thin tissue sections using very high-frequency ultrasound (>100 MHz). Under isotropic assumptions, 2DZMs can predict the BSC accurately; nevertheless, in the case of dense media, where the locations of the scatterers can be correlated, some of the theoretical assumptions fail, which requires introduction of the structure-factor model (SFM). Using experimental and simulated data, this presentation will review ...