Intraductal Ultrasonography for the Assessment of Preoperative Biliary and Pancreatic Strictures

Abstract

Diseases of the biliary and pancreatic ducts are often difficult to diagnose. Although transcutaneous ultrasonograpy, computer tomography and magnetic resonance greatly improved in performance, two major problems have not been completely solved yet: first, the differentiation of malignant and benign bile duct strictures, and, second, the assessment of the resectability of carcinomas underlying biliary strictures. Ultrasound probes can be inserted through the working channel of the duodenoscope and passed selectively both into the biliary and pancreatic ducts. Ultrasound frequencies of 20 or 30 MHz enable a penetration of up to 2 cm and a resolution of 0.07 to 0.18 mm. The main clinical indication for intraductal ultrasonography of the biliary tract is obstructive jaundice, which requires assessment of bile duct strictures and local tumor staging. Miniprobes can contribute to the differential diagnosis of strictures localized in the main pancreatic duct, and also to localizing small endocrine tumors. Small tumors of the papilla of Vater can be staged before a possible endoscopic resection. Feasibility of the method is excellent in expert hands with almost no added morbidity.