Broadband measurement of the scattering-to-attenuation ratio for Albunex (R) at 37 degrees C

The attenuation coefficient and backscatter coefficient of Albunex(R) were measured over a wide range of concentrations and frequencies (at a temperat ure of 37 degrees C), and were used to calculate the scattering-to-attenuat ion ratio (STAR) value. Each of these quantities exhibited concentration de pendence in agreement with predictions from simple scattering theory: the b ackscatter coefficient grew linearly with concentration, the power of the t ransmitted signal decreased exponentially with concentration due to attenua tion, and the STAR was independent of concentration scaling. Because of the markedly differing concentration dependence, it is necessary to consider a ll of these quantities (not just the STAR value alone) when evaluating and comparing the potential efficacy of ultrasonic contrast agents. (C) 1999 Wo rld Federation for Ultrasound in Medicine & Biology.