Standard properties of ultrasound contrast agents.

A standardization procedure for in vitro acoustic characterization of ultrasound contrast agents is presented. One new acoustic parameter for particular importance is retained: This is STAR, scattering-to-attenuation ratio, for quantification of the effectiveness of the contrast agent. The STAR expresses the ability of the contrast agent to enhance the visualization of the tissue containing the contrast agent and, at the same time, represents the degree of its absorption. So, it is desirable to produce a contrast agent with high STAR, having good scattering properties to improve the image visualization, and low attenuation to image the underlying biological structures and to avoid shadowing. In this study, we present methods for calculations and measurements of the STAR and comparison between different contrast agents.