title: Detection of choledocholithiasis: comparison of unenhanced spiral CT, US, and ERCP.
abstract: OBJECTIVE
  ERCP is an established method for the diagnosis and treatment of common bile duct stones, however, it is invasive, time-consuming, and expensive. The purpose of this study was to determine whether unenhanced spiral CT and US, compared with ERCP, have sufficient sensitivity and negative predictive value to be useful screening techniques in patients suspected of having choledocholithiasis.
  
  
  METHODS
  Over a period of 2 years, 82 patients with clinically suspected choledocholithiasis underwent unenhanced spiral computed tomography and US immediately before undergoing endoscopic retrograde cholangiopancreatography. CT/US scans and ERCP images were evaluated for the presence of bile duct stones, ampullary stones, and extrahepatic biliary dilatation.
  
  
  RESULTS
  Unenhanced spiral computed tomography (US) depicted common bile duct stones in 24 (23) of 28 patients found to have stones at endoscopic retrograde cholangiopancreatography. Five patients had stones impacted at the ampulla, all (two) of which were detected with CT (US). Computed tomography (US) had a sensitivity of 86% (82%) and a specificity of 98% (98%) in the diagnosis of choledocholithiasis.
  
  
  CONCLUSIONS
  Both unenhanced spiral CT and US are useful for evaluating suspected common bile duct stones. Unenhanced spiral CT is especially useful when the patient is likely to have ampullary stones and is a safe, more available and less expensive alternative to magnetic resonance cholangiography.
authors.affiliation: Department of Abdominal Radiology, Martin-Luther-University, Faculty of Medicine, Magdeburger Strasse 16, D-06112 Halle/Saale, Germany. pickuth@aol.com
authors.forename: D
authors.initials: D
authors.lastname: Pickuth
authors.forename: R P
authors.initials: RP
authors.lastname: Spielmann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002760:Cholangiopancreatography, Endoscopic Retrograde; D005260:Female; D042882:Gallstones / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography