Direct strain estimation in elastography using spectral cross-correlation

Spectral estimation of tissue strain has been performed previously by using the centroid shift of the power spectrum or by estimating the variation in the mean scatterer spacing in the spectral domain. The centroid shift meth od illustrates the robustness of the direct, incoherent strain estimator. I n this paper, we present a strain estimator that uses spectral cross-correl ation of the pre- and postcompression power spectrum. The centroid shift es timator estimates strain from the mean center frequency shift, while the sp ectral cross-correlation estimates the shift over the entire spectrum, Spec tral cross-correlation is shown to be more sensitive to small shifts in the power spectrum and, thus, provides better estimation for smaller strains w hen compared to the spectral centroid shift. Spectral cross-correlation sha res all the advantages gained using the spectral centroid shift, in additio n to providing accurate and precise strain estimation for small strains. Th e variance and noise properties of the spectral strain estimators quantifie d by their respective strain filters are also presented. (C) 2001 World Fed eration for Ultrasound in Medicine & Biology.