Optimizing tissue ablation by focused ultrasound using a phase-shift perfluorocarbon nanoemulsion (2013)
Undergraduates: Connor Puett, Paul Sheeran Linsey Phillips, Ph.D.
Faculty Advisor: Paul Dayton
Department: Applied Sciences
Tissue ablation by high-intensity focused ultrasound (HIFU) can be accomplished using lower intensities if phase-shift perfluorocarbon (PFC) nanodroplets are present in the acoustic field. These nanodroplets seed the tissue with cavitation sites when they are vaporized to microbubbles by acoustic energy. Decreased intensity requirements would improve the safety of HIFU and make it a viable option for a broader range of disease sites. However, to be clinically useful, control over ablation must be maintained, and this control can be problematic when cavitation is used to enhance heating. Appropriate acoustic parameters (intensity and insonation time) must be selected for the available PFC concentration. This study explores the relationships between vaporization and ablation, HIFU acoustic parameters, and the concentration of PFC nanodroplets in albumin-acrylamide gels. The results demonstrate that ablation lesions of predictable size, shape, and location can be generated in PFC-containing gels, using intensities low enough to avoid ablation in regions containing no PFC. The results also identify the optimum acoustic parameters to achieve an ablation lesion of desired size for a given PFC concentration. These in vitro findings provide the information needed to explore PFC-enhanced HIFU in the animal model and are an important step toward developing a potentially useful clinical tool.