Bismuth Grade III Bile duct stricture
- Since its introduction, MRCP has rapidly become an important tool for visualizing the biliary system.
- MRCP takes advantage of the fact that bile has a high signal intensity on T2-weighted images, whereas the surrounding structures do not enhance and can be suppressed during image analysis.
- MRCP is as sensitive as US for helping detect cholelithiasis and is superior to sonography for helping diagnose CBD stones, malignant biliary obstruction, and benign pancreatic disease.
- The presence of biliary dilation can be accurately detected by MRCP in 97-100% of patients. The level of obstruction is correct in almost 87% cases.
- Bile duct calculi also appear as low signal intensity. CBD strictures and stones can be differentiated as a cause of obstruction in most cases.
- MRCP also is very useful in helping identify cholangiocarcinoma, which characteristically appears as enhancement in delayed images.
- More importantly, MRCP provides valuable staging information because of its ability to help visualize the hepatic parenchyma and surrounding vascular structures in the same examination.
- Benign strictures due to sclerosing cholangitis are multifocal and alternate with slight dilatation or normal-caliber bile ducts, producing a beaded appearance.
- Dilatation of both the pancreatic and bile ducts viewable using MRCP is highly suggestive of a pancreatic head malignancy. Side-branch ectasia is the most prominent and specific feature of chronic pancreatitis. Thus, MRCP provides a viable alternative to ERCP and allows imaging of the biliary tree when ERCP is unsuccessful, although, unlike ERCP, it is not therapeutic.
- In 1982, Bismuth proposed an anatomic classification of bile duct strictures, based on location, into the following 5 types:
- Type 1: This is a low common hepatic duct stricture. At least 2 cm of the hepatic duct is intact.
- Type 2: This is a mid common hepatic duct stricture. The hepatic duct stump is smaller than 2 cm.
- Type 3: This is a hilar stricture. The common hepatic duct is not involved, but the confluence of right and left hepatic ducts is intact.
- Type 4: In this type, the hilar confluence is destroyed. The right and left hepatic ducts are separated.
- Type 5: The aberrant right sectorial duct is involved, alone or with the CBD.
- The modified Bismuth and Corlett classification of hilar cholangiocarcinoma is the most widely adopted anatomical classification of this tumor. The following 4 types are recognized:
- Type 1: The confluence of the hepatic ducts is not involved, but the tumor generally is within 2 cm of the hilum.
- Type 2: The obstruction is limited to the confluence of the right and left hepatic ducts.
- Type 3a: The confluence is involved, with extension of the tumor into the right hepatic duct.
- Type 3b: The confluence is involved, with extension of the tumor into the left hepatic duct.
- Type 4: The tumor extends into the right and left hepatic ducts.