An <i>ex vivo</i> investigation on the potential of catheter-assisted pulsed focused ultrasound ablation for arterial plaques

Existing medications and interventional procedures for removing arterial plaques might cause vessel injuries or hemorrhages, leading to post-treatment complications. To reduce these risk factors, this study developed a minimally invasive technique by combining focused ultrasound (FUS) with an acoustically reflective hard surface. FUS with 500 kHz frequency was focused on the interface between a Nitinol catheter and soft tissue. Cavitation threshold was determined by monitoring the peak amplitude values of the broadband signals in experiments with agar phantoms and pork belly fat samples using a 10 MHz passive cavitation detector. It was observed that an early onset of cavitation event occurred when FUS was targeted at the tissue-catheter interface. Treatment was performed on pork belly fat and carotid artery plaque samples attached with and without a 3 mm diameter catheter. FUS bursts of 2500-cycle and 10% duty-cycle with peak-negative-pressure of 2 and 4 MPa were applied on pork belly fat and plaque samples, respectively, for 3 min. Catheter-assisted FUS treatment resulted in the enhanced fragmentation of lipid contents from pork belly and plaque samples. In contrast, FUS-only treatment showed negligible amount of plaque depletion. This study demonstrated the potential of catheter-assisted FUS therapy for plaque ablation.