The College of Engineering is sponsoring a seminar by David Li, a post-doctoral fellow in the departments of Chemical Engineering and Bioengineering at the University of Washington. With a PhD in Biomedical Engineering, he is researching phase-changing nanomaterials for diagnostic and therapeutic ultrasound, and sonochemistry. His talk, “Phase-Changing Contrast Agents for Medical Imaging and Therapy Monday,” will be given on Monday, October 29, from 3:00 to 4:00 p.m. in Holmes 244. As he explains, microbubbles are an FDA-approved ultrasound contrast agent used to enhance visualization of the vasculature. However, they are limited to intravascular imaging applications and suffer from a short lifespan, lasting only minutes in the circulation upon injection. Phase-change contrast agents offer novel ways of approaching diagnostic and therapeutic techniques beyond what is possible with conventional microbubble contrast agents. These are synthesized and administered as tiny liquid nanodroplets that can freely diffuse cross the vessel wall for extravascular imaging or therapy. Using a sufficiently high-amplitude acoustic or optical pulse, the droplets can be vaporized, forming microbubbles that can be used in the same manner as conventional, FDA-approved ultrasound contrast agents. In this presentation, Dr. Li will discuss the theory and design challenges associated with using droplet-based theranostics (therapy plus diagnostics). He will also present new nonlinear imaging and therapy techniques that can provide molecular specificity and greater depth of penetration, while eliminating imaging artifacts designed around phase-change contrast agents.