[Ultrasound in gastroenterology. Biliopancreatic system]

Abstract

GALLBLADDER: Ultrasound has become widely accepted for the diagnosis of gallbladder disease. Sensitivity for cholecystolithiasis is approximately 100%. Cholezystitis including its acute and chronic complications is also a domain of ultrasound techniques. An obstruction of the bile ducts and its localization are easily recognized. Clarifying the etiology is yet another question far more difficult to answer. Ultrasound contrast agents have proven to be useful for clarification of biliary tumors. Gallbladder polyps are well detectable. Adenomas of > 1 cm are an indication for surgery, the detection of a vessel at the polyps' base by color duplex ultrasound is helpful. Gallbladder carcinomas as a disease of the older age with few early symptoms are usually detected at a late stage when the liver is already infiltrated. BILE DUCT SYSTEM: Even with the most modern equipment the sensitivity for choledocholithiasis is still largely dependent on the examiner's expertise und differs between 25% and 100%. Endosonography is more efficient (94-100%). Primary sclerosing cholangitis shows bile duct dilation like "a string of pearls" and typical perihepatic lymph node enlargement. Differentiation from early cholangiocarcinoma is difficult. PANCREAS: In diagnostic imaging of the pancreas ultrasound stands at the beginning of a diagnostic cascade. In contrast to other competing examinations it can be repeated at any time and without X-ray exposure. The informative value, though, is largely dependent on the examiner's expertise. Usually, a CT scan is additionally performed when ultrasound examination is incomplete or limited through examination condition or if doubts on diagnostic accuracy arise. In cases of acute pancreatitis, especially the assessment and follow-up of complications (exudation, necrosis, pseudocysts, vascular complications, and obstructive effects) are precious. Ductal adenocarcinoma seems to be less vascularized in comparison to the surrounding tissue, while endocrine tumors and macro- and microcystic adenoma are rather hypervascularized.