Shear Wave Speed Estimation from Crawling Wave Sonoelastography: A comparison between AM-FM Dominant Component Analysis and Phase Derivation Methods

Crawling Wave Sonoelastography (CWS) offers quantitative estimation of shear wave speed (SWS) in soft tissues. Recently, two different methods to estimate the SWS from the crawling wave patterns have been proposed. The first method is based on the spatial phase derivation from the slow-time signal (CWS-PD) using the knowledge of the difference in vibration frequency (DVF) between external sources. The second method is based on the AM-FM Dominant Component Analysis (DCA) model, which allows estimating the spatial frequency without a-priori information of the DVF and without any noise model assumptions. In the present study, a comparison of the performance of CWS-PD and AM-FM-DCA for the estimation of SWS is presented through experiments with three gelatin phantoms with different concentrations (10%, 13% and 16%). Both CWS-PD and AM-FM-DCA provided similar SWS estimates with generally good agreement with the values obtained from mechanical measurements. Both methods presented larger errors for the 16% gelatin phantom and frequencies below 220 Hz due to the increased difficulty in tracking shear waves with longer wavelengths. These results suggest that further research may be needed for a more accurate evaluation of stiffer materials using CWS.