Figure 9a.  Hilar cholangiocarcinoma with proximal extension into the right and left hepatic bile ducts in a 75-year-old man. (a) MR cholangiogram demonstrates dilatation of the intrahepatic bile ducts (arrowheads) secondary to hilar cholangiocarcinoma, which has extended proximally to involve the right and left hepatic ducts (arrows). (b) MR cholangiogram obtained after injection of contrast material into biliary drainage catheters helps confirm the obstructing hilar lesion and its proximal extent (arrows) as demonstrated in a. (Reprinted, with permission, from reference 6.)