Dynamics of volatile phase-change contrast agents: Theoretical model and experimental measurements

Interest in perfluorocarbon (PFC) phase-change contrast agents (PCCAs) is motivated by the fact that they can be triggered to transition from the liquid state to the gas state by an externally applied acoustic pulse. This property opens up new approaches to ultrasound imaging and therapy. Insight into the physics of this process is vital for effective use of PCCAs and for anticipating bioeffects. Our paper reports on the development of a new theoretical model that describes the conversion of a PFC droplet into a vapor bubble and subsequent bubble evolution. The development of the model was specifically aimed at exploring the complex behavior which is demonstrated experimentally by volatile PFC droplets with low boiling points but has not been well-described theoretically so far. The model is validated by comparison with in vitro experimental data acquired by ultra-high-speed video microscopy for decafluorobutane (DFB) and octafluoropropane (OFP) microdroplets of different sizes.