Background and study aims: Intraductal ultrasonography (IDUS), a new ultrasonographic diagnostic procedure, was used to assess the presence of extrahepatic bile duct stones.
Patients and 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.
Conclusion: IDUS could be a useful modality in the diagnosis of extrahepatic bile duct stones.