Attenuation estimation using spectral cross-correlation.

Estimation of the local attenuation coefficient in soft tissue is important both for clinical diagnosis and for further analysis of ultrasound B-mode images. However, it is difficult to extract spectral properties in a small region of interest from noisy backscattered ultrasound radio frequency (RF) signals. Diffraction effects due to transducer beam focal properties also have to be corrected for accurate estimation of the attenuation coefficient. In this paper, we propose a new attenuation estimation method using spectral cross-correlation between consecutive power spectra obtained from the backscattered RF signals at different depths. Since the spectral cross-correlation method estimates the spectral shift by comparing the entire power spectra, it is more robust and stable to the spectral noise artifacts in the backscattered RF signals. A diffraction compensation technique using a reference phantom with a known attenuation coefficient value is also presented. Local attenuation coefficient estimates obtained using spectral cross-correlation are within 2.3% of the actual value with small estimation variances, as demonstrated in the simulation results.