Hilar cholangiocarcinoma: comparative study with sonography and CT.

Fifty-one patients were studied to determine the relative accuracy of sonography and computed tomography (CT) in the evaluation of hilar cholangiocarcinoma. Both sonography and CT permitted detection of intrahepatic bile duct dilatation in all patients. Nonunion of right and left intrahepatic bile ducts was identified with sonography in 90% and with CT in 94% of patients. The tumor per se was depicted by sonography in 21% and by CT in 40% of patients. Forty tumors (78%) were of the infiltrating type, seven (14%) were exophytic, and four (8%) were polypoid. With sonography, infiltrating and exophytic tumors were difficult to depict, whereas polypoid tumors were well identified. With CT, infiltrating tumors were more difficult to depict than were exophytic or polypoid tumors. On CT scans, depicted tumors of the infiltrating type showed high attenuation and an indistinct margin, whereas exophytic and polypoid tumors showed low attenuation and a well-defined margin. Sonography and CT were comparably accurate in determining the level of obstruction in hilar cholangiocarcinoma even when no mass was depicted. CT was superior to sonography in depicting tumor per se and in demonstrating associated findings.