IDUS for Biliary Tract
Intraductal ultrasonography (IDUS) normally delineates 2–3 layers of the bile duct wall. On the other hand, IDUS can identify carcinoma as a hypoechoic area of irregular thickness. IDUS generally is reliable for diagnosis of extrahepatic bile duct cancer, but IgG4-related sclerosing cholangitis (IgG4-SC) can be difficult to distinguish from malignant strictures. Even so, in IgG4-SC, IDUS can depict circular, symmetric wall thickening with smooth outer and inner margins, associated with homogeneous internal echo in narrowed ducts. While endoscopic cholangiography is unreliable in detection of small gallstones after endoscopic lithotripsy, IDUS is more successful in detecting small gallstones in such cases. In conclusion, IDUS and 3D-IDUS are useful for differentiating between malignant biliary strictures and benign ones, including IgG4-SC, as well as for detection of small bile duct stones.
KeywordsBiliary tract cancer Bile duct stones IgG4-related sclerosing cholangitis