Gallbladder Cryoablation: Proof of Concept in a Swine Model for a Percutaneous Alternative to Cholecystectomy

Hugh C. J. McGregor, Maythem Saeed, Andrew Surman, Eric C. Ehman, Steven W. Hetts, Mark W. Wilson, Miles B. Conrad

To investigate the feasibility of percutaneous gallbladder cryoablation (GBC) under CT guidance in a swine model with histopathologic correlation. Institutional Animal Care and Use Committee approval was obtained for this study protocol. Five pigs underwent GBC. Under CT guidance, 3-4 cryoprobes were positioned percutaneously at the gallbladder margins. Thermocouple probes were placed percutaneously at the gallbladder fundus, neck, free wall, and gallbladder fossa. Two freeze-thaw cycles ranging from 10 to 26 min were performed. The subjects were sacrificed 5 h after cryoablation. The gallbladder and bile ducts were resected, stained, and examined microscopically. GBC was completed in all subjects. A 10-mm ablation margin was achieved beyond all gallbladder walls. Thermocouple probes reached at least -20 °C. Intra-procedural body temperature decreased to a minimum of 35 °C but recovered after the procedure. Intra- and post-procedural vital signs otherwise remained within physiologic parameters. Non-target ablation occurred in the stomach and colon of the first two subjects. Histology demonstrated complete denudation of the gallbladder epithelium, hemorrhage, and edema within the muscularis layer, and preservation of the microscopic architecture of the common bile duct in all cases. Percutaneous gallbladder cryoablation is feasible, with adequate ablation margins obtained and histologic changes demonstrating transmural necrosis. Adjacent structures included in the ablation may require conservative ablation zones, hydrodissection, or continuous saline lavage.