Molecular imaging agents for ultrasound

Schematic representation of molecular US imaging using nano-sized ultrasound contrast agents (nUCAs). (a) Molecular US imaging using echogenic nanobubbles (NBs) which extravasate to target extravascular markers. (b) Molecular US imaging using phase-change droplets (PCDs) which retain their nano-size to extravasate and transform to echogenic micron-particles upon heat activation. (c) Molecular US imaging using gas-generating nanoparticles (GGNPs) which extravasate to the tumor microenvironment and undergo reactions producing echogenic gas bubbles.