Estimation of frequency-dependent attenuation based on parametric spectral analysis and correlation lags of the demodulated echo signal.

Two new methods for estimating frequency-dependent attenuation are proposed which improve the compromise between the estimation variance of this parameter and the analyzed tissue volume: 1) parametric spectral estimation of the demodulated signal, based on fast Kalman filtering (ARC), 2) implementation of a new mean frequency estimator derived from all the available autocorrelation lags (ACn) of the demodulated signal. Both methods are applied to simulated echo signals. The results are compared to those of other already existing estimators. Both ARC and ACn methods provide equivalent results and a better estimation of attenuation (accuracy ranging from 1.3 to 8%) than the previous methods do (accuracy ranging from 4 to 66%), for analysis windows ranging from 1.5 to 20 microseconds.