Impact of tumor size and cirrhotic background for differentiating HCC and ICC with CEUS: does it matter for patients undergoing hepatectomy?

Objectives: The aim of this study was to investigate the role of contrast-enhanced ultrasound (CEUS) in differentiating hepatocellular carcinoma (HCC) vs. intrahepatic cholangiocarcinoma (ICC) and primary liver cancer vs. benign liver lesions for surgical decision making. Methods: Data from 328 patients (296 primary liver cancer patients: 232 HCC and 64 ICC patients and 32 benign hepatic lesion patients) who underwent hepatectomy at our center were retrospectively collected from 2010 to 2015. Conventional ultrasound (US) and CEUS were performed for all patients before hepatectomy. Enhancement patterns in CEUS were classified and compared for HCC vs. ICC and for primary liver cancer vs. benign lesions. Results: Primary liver cancer and hepatic benign lesions could be distinguished by CEUS in different phases. The most obvious differences were in the portal and delayed phases, in which benign lesions could still show hyperenhancement (46.9% vs. 0.0% and p < 0.001 in the portal phase; 43.7% vs. 0.0% and p < 0.001 in the delayed phase). For differentiating HCC and ICC, our results revealed that HCC and ICC displayed different enhancement patterns in the arterial phase (p < 0.001) and the portal phase (p < 0.001). In the subgroup analyses, both HCC and ICC showed a high rate of homogeneous hyperenhancement during the arterial phase when tumors were <= 5 cm (87.2% vs. 64.0% and p = 0.008) or the Ishak score was >= 5 (75.8% vs. 42.9% and p = 0.023), although there was statistical difference. However, during the portal phase, ICC > 5 cm showed significantly more frequent hypoenhancement (92.3% vs. 54.5% and p < 0.001) and less isoenhancement (7.7% vs. 45.5% and p < 0.001) than HCC; additionally, during the portal phase, there was no statistical difference in the enhancement patterns of ICC with different hepatic backgrounds. Conclusions: Tumor size and hepatic background should be taken into consideration when distinguishing HCC and ICC before surgery. However, CEUS is a helpful tool for differentiating malignant and benign hepatic lesions. For patients who require surgical treatment, CEUS may help with surgical decision making.