Effect of Acoustically Responsive Droplet-based Low-intensity Histotripsy on Canine Prostate

Low-intensity histotripsy (LIH) is a novel and safe technique for tissue ablation. This study aimed to explore the effects of LIH on canine prostate tissue and identify the degree of acute injury to the gland. We constructed and evaluated two types of acoustically responsive droplet (ARD) emulsions using either perfluoropentane (PFP) with a lipid shell or perfluoromethyl-cyclopentane (PFMCP) with lauromacrogol (L) injection. Twenty beagles were assigned to four experimental groups: ultrasound (US) + PFP (n = 6), US + PFMCP-L (n = 6), PFMCP-L (n = 5) and PFP (n = 3). The ARDs were injected transcutaneously and transabdominally into normal canine prostates under US-guided imaging. Subsequently, focused therapeutic US was employed to induce acoustic droplet vaporization and bubble cloud cavitation. The mechanical damage to canine prostate tissue was evaluated using gross and histological examination. Gross specimens showed that the injured area was dark brown. Hematoxylin and eosin-stained tissue sections of the damage zone showed significant cavity formation and interstitial edema. The total tissue damage scores in the US + PFP group were compared to those of the other three experimental groups. No statistically significant differences were observed in the extent of tissue damage and total scores among the US + PFMCP-L, PFMCP-L and PFP groups. We achieved significant mechanical tissue damage in the canine prostate using PFP ARD-based LIH that proved to be superior to that using PFMCP ARDs with LIH.