Evaluation backscattering coefficients of heterogeneous media containing multispecies scatterers and lipids

Many attempts have been reported to evaluate tissue characterization from echo signals using the backscatter coefficient (BSC) as an indicator. In the evaluation of the BSC of the biological tissues, it is known that the effects of attenuation properties such as scattering attenuation and absorption attenuation, as well as interference between different scatterers, are significant. In this study, the effects of attenuations and interference were verified by evaluating a phantom with high absorption attenuation and a phantom with a mixture of two types of scatterers. Both the reflector method and the reference phantom method were applied to BSC evaluation for these phantoms, and the accuracy of the evaluation was verified. The results suggest that the effect of the acoustic impedance ratio between the scatterer and the surrounding medium tends to be reflected in the accuracy of the evaluation in media with large absorption attenuation. On the other hand, the difference between the mathematical theory and the actual evaluation results was observed due to interference effects. In terms of the accuracy of the evaluation method, the reflector method is effective in the vicinity of the focus, while the reference phantom method is effective in terms of application.