Thrombolysis enhanced by dual-frequency highintensity focused ultrasound

It has been demonstrated that high-intensity focused ultrasound can be an efficient method to induce thrombolysis. Excessive thermal effect on neighboring tissue is however a concern. The goal of this work is to test the efficacy of dual-frequency ultrasound-induced thrombolysis, with the aim to reduce the acoustic power required to achieve the same lysis rate (mass loss of blood clots over time) as single-frequency ultrasound. In vitro clots of mouse blood were prepared and placed at the focus of two piezoelectric ultrasound transducers (center frequencies were 0.95 MHz and 1.5 MHz, respectively). 0.65 W ultrasound waves with 10% duty cycle were employed in both single- and dual-frequency ultrasound exposures. The mass losses of the clots were recorded to obtain the lysis rate after each test. It was found that dual-frequency results in more efficient thrombolysis. Cavitation bubble modeling was also conducted for both single- and dual-frequency ultrasound to explain the experimental founding.