Endoscopic high-intensity focused US: technical aspects and studies in an in vivo porcine model (with video)

BackgroundHigh-intensity focused US (HIFU) is becoming more widely used for noninvasive and minimally invasive ablation of benign and malignant tumors. Recent studies suggest that HIFU can also enhance targeted drug delivery and stimulate an antitumor immune response in many tumors. However, targeting pancreatic and liver tumors by using an extracorporeal source is challenging due to the lack of an adequate acoustic window. The development of an EUS-guided HIFU transducer has many potential benefits including improved targeting, decreased energy requirements, and decreased potential for injury to intervening structures.ObjectiveTo design, develop, and test an EUS-guided HIFU transducer for endoscopic applications.DesignA preclinical, pilot characterization and feasibility study.SettingAcademic research center.PatientsStudies were performed in an in vivo porcine model.InterventionThermal ablation of in vivo porcine pancreas and liver was performed with EUS-guided focused US through the gastric tract.ResultsThe transducer successfully created lesions in gel phantoms and ex vivo bovine livers. In vivo studies demonstrated that targeting and creating lesions in the porcine pancreas and liver are feasible.LimitationsThis was a preclinical, single-center feasibility study with a limited number of subjects.ConclusionAn EUS-guided HIFU transducer was successfully designed and developed with dimensions that are appropriate for endoscopic use. The feasibility of performing EUS-guided HIFU ablation in vivo was demonstrated in an in vivo porcine model. Further development of this technology will allow endoscopists to perform precise therapeutic ablation of periluminal lesions without breaching the wall of the gastric tract.