Purpose: We investigated the added value of the hypointensity on hepatocyte-phase (HP) imaging of gadoxetic acid-enhanced MRI (EOB-MRI) in the 2014 version of the Liver Imaging Reporting and Data System (LI-RADS) for distinguishing hepatocellular carcinoma (HCC) from benign hepatic lesions in patients with chronic liver disease.Methods: We retrospectively evaluated targeted lesions (111 HCCs, 28 benign hepatic lesions) of 139 patients (101 men, 38 women; aged 18 to 89 years, mean age, 68 « 11 years) with chronic liver disease. EOB-MRI and dynamic contrast-enhanced computed tomography (CECT) were performed within 3 months. Two abdominal radiologists independently reviewed 3 imaging datasets: (1) EOB-MRI without an HP image using the LI-RADS system (MR imaging without HP); (2) EOB-MRI with an HP image using a modified version of the LI-RADS system in which hypointensity on the HP image was used as an additional major criterion of malignancy (MR imaging with HP); and (3) dynamic contrast-enhanced computed tomography (CECT) images using the LI-RADS system. We evaluated intra-and inter-reader agreement with kappa statistics along with 95% confidence intervals and compared diagnostic sensitivity and specificity of the 3 imaging datasets with McNemar's test.Results Conclusion: The use of an HP image from EOB-MRI as an additional major criterion improved the sensitivity of LI-RADS to distinguish HCCs from benign hepatic lesions while retaining high specificity.

Hypointensity in the hepatocyte phase is believed to be a key feature of hypovascular early hepatocellular carcinoma, which indicates malignancy. The 3 cases we present suggest that the converse is not true. Three small hepatocellular lesions showed isointensity/hyperintensity on gadoxetic acid-enhanced, hepatocyte-phase magnetic resonance images and were pathologically confirmed as early hepatocellular carcinomas. We conclude that isointensity or hyperintensity in the hepatocyte phase does not always represent benignity of hepatocellular lesions in the cirrhotic liver.