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: The sensitivities of MR imaging were statistically higher with HP (Reader 1, 95%[107/111]; Reader 2, 95%[106/111]) than without HP (Reader 1, 84%[93/111], P= 0.002; Reader 2, 86%[96/111], P= 0.002). Specificity was comparably high between MR imaging with HP (Reader 1, 96%[27/28]; Reader 2, 96%[27/28]) and dynamic CECT (Reader 1, 100%[28/28], P= 0.317; Reader 2, 100%[28/28], P= 0.317) and MR imaging without HP (Reader 1, 96%[27/28], P= 1.00; Reader 2, 100%[28/28], P= 0.317).

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.