P2B-1 Estimation of Tissue Attenuation Coefficients Using Contrast Agent

Attenuation coefficient (Att. Coef.) is an acoustic parameter for tissue characterization. Two major techniques for Att. Coef. estimation are the backscattering and transmission methods. Backscattering method is suitable for general applications, but the speckle interference makes it inaccurate. Transmission method is more reliable, but it is suitable for peripheral organs only, due to the need of a separate transmitter. With the aid of contrast agent (microbubble), a new way to estimate the Att. Coef. of soft tissues is proposed, which is suitable for general applications. Since microbubble is a highly nonlinear object, using the multiple frequencies generated by microbubbles behind the tissue, the Att. Coef. can be estimated in transmission mode. Since the harmonics are generated by common microbubbles, their relative strengths can be predicted by theory and measured for Att. Coef. estimation. The power spectrum of echo signals are estimated using periodogram. For liver tissue, the frequency dependent Att. Coef. (beta) is estimated as 0.1 dB/cm/MHz. Additional performances of the new technique will be evaluated further in the future