Ultrasound contrast agents. State of the art.

In the development of sonographic contrast agents it is clear that the material properties of the contrast have a profound effect on the resulting effectiveness of the product requiring careful manipulations of its properties. The important parameters are particle size, imaging frequency, density, compressibility, particle behavior (surface tension, internal pressure, bubble-like qualities), and equally important biodistribution characteristics and tolerance. Particulate agents appear to be the most likely materials, and gas filled particles are by far the most effective reflectors. However, the gas-based agents reported to date appear to have a short blood half-life. The fluorocarbon emulsions and the solid particles with entrapped air appear to be the most promising agents for abdominal imaging.