The T1W Hyperintense Signal on the Surface of Distal Segment of Bile Duct Tumor Thrombi and Its Significance

Rationale and Objectives: To evaluate the magnetic resonance (MR) findings of bile duct tumor thrombi (BDTT) and intraductal growing-type cholangiocarcinoma (IDG-type CC), especially focusing on the distal segment of intrabiliary tumors. Materials and Methods: Twenty-nine cases of hepatocellular carcinoma with BDTT and 17 cases of IDG-type CC were available for retrospective review. The following MR findings were evaluated: presence of necrosis and T1-weighted (T1W) hyperintense signal on the surface of the distal segment of intrabiliary tumors, bile duct wall thickening adjacent to the tumor, dilation of bile duct of the tumor-bearing segment, location and maximum diameter of intraductal mass, and presence of a hepatic parenchymal mass. Results: There was significant difference in T1W hyperintense signal on the surface of the distal segment of intrabiliary tumors between BDTT and IDG-type CC (P < .05). The T1W hyperintense signal detected in BDTT was identified as bile layering (9/25) or hemobilia (16/25) pathologically. For the diagnosis of BDTT, the sensitivity and specificity of T1W hyperintense signal was 86.2% and 100%, respectively. There was significant difference in necrosis at the distal end of intrabiliary tumors and presence of hepatic parenchymal mass between BDTT and IDG-type CC (P < .05). However, no statistical significance was found in bile duct dilation, the absence of wall thickening, the location of intraductal mass, or the maximum diameter of intrabiliary mass between the two groups (P > .05). Conclusions: The T1W hyperintense signal on the distal segment of intrabiliary mass was because of concentrated bile deposits or hemobilia. The sign of T1W hyper signal on the distal segment is valuable to differentiate BDTT and IDG-type CC.