An ultrasonically actuated fine-needle creates cavitation in bovine liver

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.

Needle bevel geometry influences the flexural deflection magnitude in ultrasound-enhanced fine-needle biopsy

“…In addition, greater tip deflections could enhance bioeffects, e.g. cavitation, as suggested by a recent study 35 , which could be helpful in the development of applications for minimally invasive surgical interventions. Considering that it has already been shown that increasing the total acoustic power could increase biopsy yield in USeFNAB 13 , further quantitative study on sample yield and quality is needed, to assess the detailed clinical benefits of the studied needle geometries.…”

Needle Bevel Geometry Influences the Flexural Deflection Magnitude in Ultrasound-Enhanced Fine-Needle Biopsy

“…In addition, greater tip deflections could enhance bioeffects, e.g. cavitation, as suggested by a recent study 35 , which could be helpful in the development of applications for minimally invasive surgical interventions. Considering that it has already been shown that increasing the total acoustic power could increase biopsy yield in USeFNAB 13 , further quantitative study on sample yield and quality is needed, to assess the detailed clinical benefits of the studied needle geometries.…”