Histotripsy of the hepatic capsule and the gastric wall: acute treatment effects in a swine model.

[PURPOSE] To evaluate the safety of histotripsy at the hepatic capsule when the treatment zone extends into the gastric wall in a live porcine model.

[METHODS] Spherical 2.5 cm histotripsy treatments ( = 12 treatments) were performed in the livers of six swine with treatment margins extending ∼5 mm into the adjacent gastric wall. Each animal received two treatments: One each with a gas-filled and collapsed stomach. Post-procedural contrast-enhanced CT was performed prior to euthanasia, necropsy, and gross and histopathology.

[RESULTS] Histotripsy of the liver and adjacent stomach was technically successful in all cases (12/12). There was no statistically significant difference in treatment zone size when the stomach was inflated or collapsed. Gross pathologic evidence of gastric injury was noted in 12/12 subjects without evidence of perforation or gastric leak. CT evidence of gastric injury was observed in 10/12 treatments without evidence of gastric perforation or leakage noted (12/12). Stomach histopathology confirmed injuries as partial (non-transmural) in 11/12 cases and complete (transmural) in 1/12 cases (collapsed stomach).

[CONCLUSIONS] Histotripsy performed at the hepatic capsule with treatment margins extending into the stomach generally results in minor, partial thickness gastric injuries, which are not worsened by the presence of gas. Full thickness injuries are however possible and caution should be exercised to minimize the amount of stomach wall overlap.