Ultrasound-mediated sonothrombolysis presents several advantages over conventional treatments, including reduced risk of bleeding and lower dosage of pharmaceutical agents. A deeper understanding of the mechanisms on ultrasound-induced clot deformation can help advance scientific advancement and clinical translation. In this study, we used high-speed camera imaging to assess clot deformation of retracted bovine clots subject to one 500-μm ultrasound pulse at peak negative pressures (PNP) of 3, 5.5, or 7 MPa, delivered using a 1-MHz transducer. At the 3 and 5.5 MPa PNP conditions, acoustic radiation force application displaces the clot. At 7-MPa PNP, the boundary of the clot is visibly deformed and structurally weakened after application of ultrasound. A pressure-dependent increase in maximum displacement was observed, rising from 0.012 mm for 3 MPa to 0.018 mm for 5.5 MPa, and 0.042 mm at 7 MPa of PNP. This corresponds to a 3.5x increase between the 3- and 7-MPa conditions. Higher pressures cause greater displacement of the clot, along with increased destruction of the clot structure. These experiments provide foundational insight into the pressure dependance on clot deformation along with increased understanding of the relationship between acoustic radiation force application and clot breakdown.
Gandhi et al. (Wed,) studied this question.