An Ultrasonically Actuated Fine-Needle Creates Cavitation in Bovine Liver

TL;DR

This study demonstrates that ultrasonically actuated fine-needles can generate cavitation in bovine liver tissue, with potential applications in medical procedures like biopsy, drug delivery, and tissue disintegration, supported by simulations and high-speed imaging.

Contribution

It provides the first combined numerical and experimental analysis of cavitation phenomena near ultrasonically actuated needles in tissue models.

Findings

Cavitation occurs at specific power thresholds.

Numerical simulations closely match experimental observations.

Cavitation spatial distribution can be controlled by power levels.

Abstract

Ultrasonic cavitation is being used in medical applications as a way to influence matter, such as tissue or drug vehicles, on a micro-scale. Oscillating or collapsing cavitation bubbles provide transient mechanical force fields, which can, e.g., fractionate soft tissue or even disintegrate solid objects such as calculi. Our recent study demonstrates that an ultrasonically actuated medical needle can create cavitation phenomena inside water. However, the presence and behavior of cavitation and related bioeffects in diagnostic and therapeutic applications with ultrasonically actuated needles are not known. Using simulations, we demonstrate numerically and experimentally the cavitation phenomena near ultrasonically actuated needles. We define the cavitation onset within a liver tissue model with different total acoustic power levels. We directly visualize and quantitatively characterize cavitation events generated by the ultrasonic needle in thin fresh bovine liver sections enabled by high speed imaging. On a qualitative basis, the numerical and experimental results show a close resemblance in threshold and spatial distribution of cavitation. These findings are crucial for developing new methods and technologies employing ultrasonically actuated fine-needles such as ultrasound-enhanced fine-needle biopsy, drug delivery and histotripsy.