title: Diagnosing extrahepatic bile duct stones using intraductal ultrasonography: a case series.
abstract: OBJECTIVE
  Intraductal ultrasonography (IDUS), a new ultrasonographic diagnostic procedure, was used to assess the presence of extrahepatic bile duct stones.
  
  
  METHODS
  The IDUS apparatus consisted of a 6-French high-frequency (20 MHz) probe. Prior to clinical application, in-vitro studies were conducted in a water tank. Clinically, IDUS was successful in 31 patients after endoscopic retrograde cholangiography. Interpretations of IDUS images were evaluated in comparison with cholangiographic and fluoroscopic findings.
  
  
  RESULTS
  Experimental testing demonstrated that stones or fragments were typically visualized as strong, high-echo images with acoustic shadowing; air bubbles were seen as fan-shaped high-echo areas or comet-shaped high-echo areas; and sludge was visualized as soft, easily changing, high-echo structures. Extrahepatic bile duct stones were visualized by IDUS in 30 of 31 patients (96.8%), while fluoroscopy and cholangiography identified 19 (61.3%) and 25 (80.6%), respectively. Accurate differentiation between stones and air bubbles was also possible.
  
  
  CONCLUSIONS
  IDUS could be a useful modality in the diagnosis of extrahepatic bile duct stones.
authors.affiliation: Dept. of Gastroenterology, Jichi Medical School, Yakushiji, Tochigi, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Ueno
authors.forename: T
authors.initials: T
authors.lastname: Nishizono
authors.forename: K
authors.initials: K
authors.lastname: Tamada
authors.forename: M
authors.initials: M
authors.lastname: Ichiyama
authors.forename: S
authors.initials: S
authors.lastname: Wada
authors.forename: T
authors.initials: T
authors.lastname: Tomiyama
authors.forename: S
authors.initials: S
authors.lastname: Tano
authors.forename: T
authors.initials: T
authors.lastname: Aizawa
authors.forename: K
authors.initials: K
authors.lastname: Kimura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017734:Bile Ducts, Extrahepatic / Q000000981:diagnostic imaging*; D002758:Cholangiography; D002769:Cholelithiasis / Q000000981:diagnostic imaging*; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D008297:Male; D008875:Middle Aged; D014463:Ultrasonography / Q000379:methods