A method to identify acoustic reverberation in multilayered homogeneous media

The presence of reverberation is a source of artifacts that can hinder the analysis of ultrasound signals and images. Besides compromising image generation, these artifacts can introduce errors in the quantitative parameter estimation in fields such as material and biological tissue characterization. A method that allows the separation between the first reflection on an interface and all the other reflections from the same interface (reverberation) could improve the quality of these images as well as the precision and accuracy in quantitative results. This work presents an algorithm for the identification of reverberating echoes in multilayered media, based on the comparison of their power spectra (estimated via FFT), through a least mean square approach, and on the temporal relationship among them. It considers that the global effect from attenuation, reflection and transmission coefficients for each layer causes spectral differences that could differentiate echoes that pass through one layer or another. The results of 10 simulations and of 60 experiments, carried out with 6 different phantoms (10 experiments with each one) are presented and discussed. It was found that the algorithm provided a correct identification for 85% of the simulated and 86.6% of the experimental echoes collected from the 60 experiments.