Hepatobiliary imaging and its pitfalls.

In summary, US is the initial imaging modality for the evaluation of acute right upper quadrant pain. It permits accurate diagnosis of acute cholecystitis and successfully identifies multiple other causes of patient symptomatology. Some of these processes lie outside the hepatobiliary system and include renal infection and obstruction, pancreatitis and its sequelae, duodenal or colonic perforation or mass lesions, peritoneal tumor spread, adrenal hemorrhage, and even remote problems, such as pneumonia. The limitations on US include incomplete imaging of the liver, most often at the dome or beneath ribs on the surface, and incomplete visualization of lesion boundaries, particularly with some infections and tumors. For these clinical scenarios, contrast-enhanced CT is complementary to US and should be encouraged. In the biliary tree, US has limitations in situations in which the ducts are not dilated and sometimes with imaging the extra hepaticducts, especially distally. For these patients, CT or MR imaging (MRCP) is especially useful. If one keeps the clinical scenario in mind and always images a patient where he or she hurts, US is a powerful and effective diagnostic method for evaluating acute right upper quadrant pain.