Ultrasound contrast materials in cardiovascular medicine: from perfusion assessment to molecular imaging.

Ultrasound imaging is widely used in cardiovascular diagnostics. Contrast agents expand the range of tasks that ultrasound can perform. In the clinic in the USA, endocardial border delineation and left ventricle opacification have been an approved indication for more than a decade. However, myocardial perfusion contrast ultrasound studies are still at the clinical trials stage. Blood pool contrast and perfusion in other tissues might be an easier indication to achieve: general blood pool ultrasound contrast is in wider use in Europe, Canada, Japan, and China. Targeted (molecular) contrast microbubbles will be the next generation of ultrasound imaging probes, capable of specific delineation of the areas of disease by adherence to molecular targets. The shell of targeted microbubbles (currently in the preclinical research and early stage clinical trials) is decorated with the ligands (antibodies, peptides or mimetics, hormones, and carbohydrates) that ensure firm binding to the molecular markers of disease.