Biliary tract imaging.

In addition to the detection of gallstones, common bile duct stones, and narrowed and dilated bile ducts, recent advancements in imaging techniques now make it possible to diagnose microlithiasis, pathology of normal-size ducts, and dysfunction of the gallbladder and the sphincter of Oddi (SO). More and more frequently, noninvasive imaging techniques obviate the risk of invasive investigation. These techniques can also take the place of unsuccessful or contraindicated direct cholangiography, and they play an essential role in treatment planning and diagnosis of postoperative complications. Transabdominal ultrasonography (TUS) remains fundamental for initial assessment of the biliary tract. Technical developments make magnetic resonance cholangiopancreatography the most promising diagnostic technique of the biliary tract. Endoscopic ultrasonography (EUS) is most helpful for detection of microlithiasis and evaluation of the ampullary region, the periductal structures, and the regional lymph nodes in neoplastic diseases. Cholescintigraphy is most valuable to assess bile dynamics in the diagnosis of gallbladder and SO dysfunction and in postoperative bile leakage.