Imaging features of microvascular invasion in hepatocellular carcinoma developed after direct-acting antiviral therapy in HCV-related cirrhosis

To evaluate imaging features of microvascular invasion (MVI) in hepatocellular carcinoma (HCC) developed after direct-acting antiviral (DAA) therapy in HCV-related cirrhosis. Retrospective cohort study on 344 consecutive patients with HCV-related cirrhosis treated with DAA and followed for 48-74 weeks. Using established imaging criteria for MVI, HCC features were analysed and compared with those in nodules not occurring after DAA. After DAA, HCC developed in 29 patients (single nodule, 18 and multinodular, 11). Median interval between therapy end and HCC diagnosis was 82 days (0-318). Forty-one HCC nodules were detected (14 de novo, 27 recurrent): maximum diameter was 10-20 mm in 27, 20-50 mm in 13, and > 50 mm in 1. Imaging features of MVI were present in 29/41 nodules (70.7%, CI: 54-84), even in 17/29 nodules with 10-20 mm diameter (58.6%, CI: 39-76). MVI was present in only 17/51 HCC nodules that occurred before DAA treatment (33.3%, CI: 22-47) (p= 0.0007). MVI did not correlate with history of previous HCC. HCC occurs rapidly after DAA therapy, and aggressive features of MVI characterise most neoplastic nodules. Close imaging evaluations are needed after DAA in cirrhotic patients. (orig.)