Empirical relationships between acoustic parameters in human soft tissues

Previously published summaries of sound speed, density, attenuation coefficient, and nonlinearity parameter, B/A, in human soft tissues are quantitatively analyzed. A highly significant empirical linear relationship is found to hold between sound speed and density for a wide range of soft tissues, including adipose, parenchymal, muscular, and connective tissues as well as body fluids. Even higher correlations occur between nondimensional parameters describing density variations and compressibility variations. Values for the nonlinearity parameter correlate significantly with sound speed and density, while the attenuation coefficient is found not to correlate significantly with any of the other parameters considered. Implications for tissue modeling and quantitative ultrasonic imaging are discussed.