Texture in B-Mode Echograms: A Simulation Study of the Effects of Diffraction and of Scatterer Density on Gray Scale Statistics

Abstract

Since the advent of gray scale echography in the early seventies, the diagnostic value of texture in B-mode echograms has been accepted without doubts. Terms like hyper- or hypoechoic, fine or coarse granular and regular or irregular are commonly used to describe in qualitative terms the subjective evaluation of the images with respect to gray level and to spatial characteristics, respectively. It would be relevant to investigate to what extent echographic images can reveal anatomic alterations of the tissue, or alternatively, to what extent the texture is determined by the physical properties of the ultrasound production and of the registration of the echograms. Burckhardt (1) and Abbott and Thurstone (2) pointed out the analogy between B-mode texture and LASER speckle for the case of large numbers of scatterers within the effective beam diameter. They derived the first-order statistics of B-mode echograms from LASER theory, showing a Rayleigh probability distribution for the echo amplitudes. Dickinson (3) reported several interesting results obtained from simulation studies using an inhomogeneous continuum model. But his study was confined to a two-dimensional description of the sound field and the tissue.KeywordsSound FieldDiffraction EffectFocal ZoneAcoustical ImageAutocovariance FunctionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.