Vessel Rupture Thresholds for Microbubble-Assisted High-Intensity Therapeutic Ultrasound - Renewal Application

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PI: Khismatullin, Damir High-intensity focused ultrasound (HITU) has recently gained recognition as a noninvasive ionizing radiation-free therapeutic method. It is being explored for treatment of cancer, neurological diseases, and circulatory system-related cardiovascular diseases. To avoid permanent damage and to identify vessel rupture thresholds for HITU devices experiments and modeling of bubble dynamics in blood vessels will be performed. This project will lead to a computational tool and a new formula for HITU safety threshold assessment that will give patients in the U.S. faster access to safe devices for treating severely debilitating diseases. It will directly support the research work of a minority graduate student. The student will receive training in computational fluid dynamics and experimental techniques for stimulation of ex vivo tissues by focused ultrasound. The outcomes of high-intensity therapeutic focused ultrasound (HITU) significantly depend on the presence of micrometer-size bubbles that can be formed in tissues as a result of acoustic cavitation. The oscillation of microbubbles in an ultrasound field generates mechanical stresses on nearby cells and tissues, leading, for example, to thrombolysis or transient opening of the blood-brain barrier (BBB) for drug delivery to brain tissue. The PI will develop a state-of-the-art computational model of cavitation of lipid-coated microbubbles in blood vessels and tissues exposed to focused ultrasound. The model will account for tissue viscoelasticity and inhomogeneity and be validated against HITU experiments on rupture of explanted vessels, to determine the critical pressure and stresses on the vessel wall above which the vessel ruptures.