Acoustic characterisation of Nycomed's NC100100 contrast agent

The authors have developed in vitro methods to characterise ultrasound contrast agents, based on correlating acoustic attenuation spectra with particle size measurements. The methods have been used to characterise Nycomed's NC100100, and to compare this with Infoson and with an experimental polymer-encapsulated contrast agent. The authors found that all the agents can be described using visco-elastic material models, with differences in particle stiffness: NC100100 was found to have bulk modulus 700 kPa, Infoson 1500 kPa and the polymer-encapsulated particles 2200 kPa. The differences are explained by differences in elastic properties and thickness of the encapsulating shell. The authors also found differences in the ratio between scattered and absorbed sound, and differences in stability when exposed to 120 mmHg hydrostatic pressure.