Contrast-enhanced ultrasound imaging features and clinical characteristics of combined hepatocellular cholangiocarcinoma: comparison with hepatocellular carcinoma and cholangiocarcinoma

PURPOSE: The purpose of this study was to retrospectively compare the clinical characteristics and imaging features on (CEUS) of combined hepatocellular cholangiocarcinoma (CHC) with those of hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC). METHODS: The clinical information and CEUS features of 45 patients with CHC from 2015 to 2019 and 1-to-1-matched control subjects with HCC and CC (45 each) were compared. RESULTS: Simultaneous elevation of α-fetoprotein (AFP) and cancer antigen (CA) 19-9 was more common in CHC than in HCC and CC. In the arterial phase, hyperenhancement (homogeneous and heterogeneous) was more common in CHC (73.3%) and HCC (100%), while peripheral rim-like enhancement was more common in CC (55.6%). In the portal phase, marked washout was significantly more frequent in CHC and CC than in HCC (42.2% and 53.3% vs. 6.7%). In the delayed phase, marked washout was more common in CHC (82.2%) and CC (93.3%) than in HCC (40.0%). The washout time (WT) was much shorter in CHC and CC than in HCC (33.8±13.1 seconds and 30.1±11.6 seconds vs. 58.4±23.5 seconds). Using the combination of simultaneous elevation of AFP and CA 19-9 with marked washout in the delayed phase and a WT <38 seconds or arterial hyperenhancement to differentiate CHC from HCC or CC, the accuracy, sensitivity, and specificity were 74.4%, 93.3%, and 55.6% and 71.1%, 80.0%, and 62.2%, respectively. CONCLUSION: Although some CEUS imaging features of CHC, HCC, and CC overlap, the combination of tumor markers and CEUS features can be helpful in differentiating CHC from HCC and CC.