Broadband measurement of the scattering-to-attenuation ratio for Albunex at 37 degrees C.

The attenuation coefficient and backscatter coefficient of Albunex were measured over a wide range of concentrations and frequencies (at a temperature of 37 degrees C), and were used to calculate the scattering-to-attenuation ratio (STAR) value. Each of these quantities exhibited concentration dependence in agreement with predictions from simple scattering theory: the backscatter coefficient grew linearly with concentration, the power of the transmitted signal decreased exponentially with concentration due to attenuation, and the STAR was independent of concentration scaling. Because of the markedly differing concentration dependence, it is necessary to consider all of these quantities (not just the STAR value alone) when evaluating and comparing the potential efficacy of ultrasonic contrast agents.