To analyze the CT findings of hepatocellular carcinoma (HCC) with bile duct tumor thrombus (BDTT).

From January 2012 to September 2018, twenty-six cases of HCC with BDTT were collected from the First Affiliated Hospital of Sun Yat-sen University and Xinhui Traditional Chinese Medicine Hospital. All cases were confirmed by pathology after operation, 64-slice spiral CT plain scan and dual-phase enhanced scan (arterial phase and portal phase) were performed. The imaging features, including distribution, density and enhancement patterns of HCC and BDTT, relationship of HCC with BDTT and situation of the bile duct wall, were retrospectively analyzed. Based on the results of operation and pathology as "golden standard", the accuracy of CT in localization and qualitative analysis of HCC with BDTT was analyzed.

All the 26 cases were diagnosed as intrahepatic and intraductal masses, HCC and BDTT clearly displayed on CT. On contrast-enhanced CT images, HCC with BDTT showed three types of enhancement pattern: fast in and fast out (18 cases, 69.2%), fast in and slow out (4 cases, 15.4%), and all low density (4 cases, 15.4%). BDTT showed dilated bile ducts filled and soft tissue masses, with distal bile duct dilation, without bile duct wall thickening. HCC was directly associated with BDTT in 24 cases (92.3%), but not associated in 2 cases (7.7%). The enhancement type of BDTT was similar with HCC lesion in 25 cases (96.2%), but different in 1 case (3.8%). The accuracy of CT in detecting HCC with BDTT was 100.0% (26/26).

The CT imaging of HCC with BDTT has certain characteristics, which is helpful for the diagnosis of the disease.