Enhancing Thermal Ablation of High Intensity Focused Ultrasound with Phase Shift Nanodroplets and Multi-focus Ablation Patterns

Local ablative treatment is a common intervention for cancers of soft tissues such as breast or liver, but they are invasive, requiring incision. High intensity focused ultrasound is being explored as an extracorporeal non-invasive option. This technology can be used to create a small focal spot of high pressures capable of thermally ablating targets as small as a grain of rice. However, this therapy carries a risk of off-target effects such as skin burns. Here, we describe a method that combines phase-shift nanodroplets (PSNDs) with multi-focus sonications to enhance volumetric ablation and ablation efficiencies while increasing the pre-focal temperatures by less than 6°C Furthermore, multi-focal ablation of 4 foci performed the best, generating a mean ablation volume of 120.2±22.4 mm
³
and ablation efficiency of 0.04 mm
³
/J when compared to an ablation volume of 61.2±21.16mm
³
and ablation efficiency of 0.02 mm
³
/J in single foci case.