Quantitative characterization of tissue state using ultrasonic backscatter features

Ultrasonic wave interaction with biological objects has been applied to characterize tissue by measuring scattered wave intensity as a function of scatterers set parameters. Especially for this purpose quantitative relationships between the scatter magnitude of ultrasonic waves and the function changes of biological tissue were established. Soft tissues are modeled as small scatterers set, which are uniformly distributed among the volume of scanner resolution. A theory of acoustic wave propagation and scattering in an inhomogeneous medium has been employed to show that received ultrasound may be expressed in terms of medium scatterers effective density that are determined by real volume scatterers density and skewness of scatterers size distribution. The work also presents results of computer-based research on the impact of local stochastic fluctuations of media characteristics, namely the coefficient of volume compressibility and density of the echo signal under ultrasound investigation of soft tissues. Comparison of estimated scatter values, with quantitative parameters measured for thyroid gland tissue is carried out based on model studies that shown dominant influence of fluctuations of volume compressibility modulus variation in tissues on the amplitude of the echo signal from region of interest.