Tissue attenuation coefficient estimation using bubble harmonics with frequency diversity

In a previous work, we developed a consistent TAC (tissue attenuation coefficient) estimator using bubble echoes. Based on temporal averaging, we can improve the estimation precision of TAC for the tissue bounded between two vessels. In this paper, we extend it to use frequency diversity for saving interrogation time by transmit multiple narrowband signals in each pulse. At first, we analyze the deterministic and stochastic properties of the diversity signals. Then a multi-band maximum likelihood diversity combiner is developed. We also provide diversity gains of different diversity estimators for comparing their estimation efficiencies. In the experimental work, we design a simplified phantom for demonstrating the performance of the purposed estimator. It is shown that the TAC estimation rate can be improved by frequency diversity. The convergence rates of single-band and multi-band estimators are compared and it is shown that the multiband estimator is more consistent than the singleband estimator.