The application of acoustic radiation force for molecular imaging and drug delivery

Abstract

Acoustic radiation force is exerted on objects in an acoustic field. By optimizing acoustic parameters to maximize this force, ultrasound contrast agents can be manipulated and concentrated with an acoustic field. This technique can be used to enhance molecular imaging and drug delivery. Ultrasonic molecular imaging employs contrast agents such as microbubbles, nanoparticles, or liposomes coated with ligands specific for receptors expressed on cells at sites of angiogenesis, inflammation, or thrombus. Concentration of these highly echogenic contrast agents at a target site enhances the ultrasound signal received from that site, promoting ultrasonic detection and analysis of disease states. It is demonstrated that acoustic radiation force can be used to displace targeted contrast agents to a vessel wall, greatly increasing the number of agents binding to available surface receptors. Radiation force can also be used for microparticle-carrier based drug delivery. Acoustically active drug-carrier vehicles can be concentrated with radiation force, and then disrupted with high-intensity ultrasound bursts, resulting in local delivery of the therapeutic agent. This talk will discuss simulations and experimental results demonstrating these applications.