Concentration-Dependent Efficacy of Endoscopic Ultrasound-Guided Ethanol Ablation of Pancreatic Tissue in the Pig

Abstract

Background: Ethanol is a commonly available agent and has been used to successfully and safely ablate cystic lesions. The aim of this study was to determine the local and systemic long-term effect of EUS-guided injection of ethanol into the pancreas of pigs using 2 ml of ethanol, in increasing concentration of 0% to 100%, diluted with normal saline. Methods: Six pigs were sedated by general anesthesia and ethanol was injected under EUS-guidance with a 22-gauge needle into the tail of the pancreas. The endpoints of this study were gross and microscopic evidence of inflammation of the pancreas and clinical tolerance. The animals were observed by determining the blood levels of amylase and lipase and by an upper abdominal CT scan. Results: Six Yorkshire breed pigs were used for this study. The animals were monitored for 7 days after the injection. CT scanning demonstrated a localized site of non-perfused pancreatic tissue measuring on average 19.4 ( ±10.5) mm in the animals that underwent an injection 40%, 60%, 80% and 100% of ethanol. By CT, there was no evidence of peri-pancreatic fat necrosis. At sacrifice, no gross lesion could be identified in the pancreatic tail of the animals that received normal saline or 20% ethanol. The other animals displayed a visible necrotic area in the tail of the pancreas (figure 1). By histology, the average maximal diameter of the lesions was 20.8 ( ±4.3) mm. The diameter of tissue necrosis correlated with the concentration of injected ethanol. Clinically, the animals appeared to tolerate the procedure well. Blood levels of amylase and lipase were within normal limits. Conclusions: The EUS-guided injection of ethanol into the pig pancreas resulted in localized tissue necrosis. This technique is a potential minimally invasive local treatment option for pancreatic neuroendocrine tumors.