Investigation of High Pulse Repetition Frequency Single-Cycle Histotripsy for Rapid Tissue Ablation.

OBJECTIVE

Single-cycle histotripsy was investigated for the rapid ablation of porcine liver using high pulse repetition frequency (PRF) pulsing methods. Recent evidence from our group has suggested that single-cycle histotripsy does not experience a decrease in ablation efficiency across a wide range of PRFs.

METHODS

Histotripsy ablation efficiency was quantified in a 1% agarose gel phantom containing a layer of red blood cells using a 500 kHz transducer with an F# of 0.61. Lesions were generated using PRFs of 500-2500 Hz at peak negative pressures of 15, 24 and 42 MPa with an 800 pulse exposure, with results compared to a low PRF control (1 Hz). Second, high PRFs were used for volumetric ablations of porcine liver using doses of 400-800 pulses per point. Tissue damage was assessed via ultrasound imaging and histologically using Masson's trichrome staining.

RESULTS

Ablation experiments in red blood cell gel phantoms showed no significant differences in ablation efficacy as PRF increased from 500 to 2500 Hz, supporting the hypothesis that single-cycle histotripsy can achieve efficient tissue ablation at high PRFs. Volumetric tissue ablation experiments showed that single-cycle histotripsy resulted in effective tissue ablation for all tested PRFs, with near complete or complete ablation observed after 600-800 applied pulses. Partial ablation in some samples at lower doses (400 pulses for 500-1500 Hz PRF, 600 pulses for 2000-2500 Hz PRF and 800 pulses for 2500 Hz PRF) suggested a slight decrease in ablation effectiveness with increasing PRF.

CONCLUSION

This study supports the hypothesis that high PRF single-cycle histotripsy can achieve faster tissue ablation while maintaining precise volumetric lesion generation.