Sparse aperture ultrasound-guided acoustic vortex tweezers for real-time microbubble aggregation in peripheral...

Acoustic vortex tweezers (AVT) have potential to enhance the targeting efficiency of drug-loaded microbubbles (MBs). However, three major challenges remain: poor real-time imaging quality with single matrix probe, difficulty in switching between imaging and AVT emission, and difficulty in using real-time imaging to guide AVT focusing. In this study, we propose a novel approach to address these challenges through the application of a sparse-aperture emission strategy integrating ultrasound flow-imaging and AVT techniques.

We present a real-time blood flow imaging (BFI) navigated AVT technique. Acoustic field characterization was conducted to compare sparse and full-aperture configurations using hydrophone measurements. Pulse parameter optimization for MBs aggregation efficiency was systematically analyzed using in vitro flow phantom models. Technical feasibility was ultimately evaluated through experiments in rabbit hindlimb venous vasculature.

The acoustic field of AVT at sparse aperture was consistent with that of full-aperture AVT. In the in vitro phantom, the acoustic pressure ranged from 0.35 to 0.65 MPa, with a pulse repetition frequency (PRF) greater than 1.5 kHz. This configuration effectively aggregated MBs at flow rates between 20 and 110 mL/h. We observed real-time venous blood flow in the lower limbs of rabbits and successfully guided AVT to aggregate MBs.

This exploratory study combining BFI and AVT provides a novel approach for the controllable accumulation and quantitative release of drug-loaded MBs in future applications.