In Vitro Demonstration of Focused Ultrasound Thrombolysis Using Bifrequency Excitation

Abstract EN

Focused ultrasound involving inertial cavitation has been shown to be anefficient method to induce thrombolysis without any pharmacological agent.

However,further investigation of the mechanisms involved and further optimization of theprocess are still required.

The present work aims at studying the relevance of abifrequency excitation compared to a classical monofrequency excitation to achievethrombolysis without any pharmacological agent.

In vitro human blood clots wereplaced at the focus of a piezoelectric transducer.

Efficiency of the thrombolysiswas assessed by weighing each clot before and after sonication.

The efficiencies ofmono- (550 kHz) and bifrequency (535 and 565 kHz) excitations were compared forpeak power ranging from 70 W to 220 W.

The thrombolysis efficiency appears to becorrelated to the inertial cavitation activity quantified by passive acoustic listening.

In the conditions of the experiment, the power needed to achieve 80% of thrombolysiswith a monofrequency excitation is reduced by the half with a bifrequency excitation.

The thermal effects of bifrequency and monofrequency excitations, studied using MRthermometry measurements in turkey muscle samples where no cavitation occurred,did not show any difference between both types of excitations when using the samepower level.