Differentiation of early hepatocellular carcinoma from benign hepatocellular nodules on gadoxetic acid-enhanced MRI

Objective: To test new diagnostic criteria for the discrimination of early hepatocellular carcinoma (HCC) from benign hepatocellular nodules on gadoxetic acid-enhanced MRI (Gd-EOB-MRI). Methods: We retrospectively analysed 34 patients with 29 surgically diagnosed early HCCs and 31 surgically diagnosed benign hepatocellular nodules. Two radiologists reviewed Gd-EOB-MRI, including diffusion-weighted imaging (DWI), and the signal intensity at each sequence, presence of arterial enhancement and washout were recorded. We composed new diagnostic criteria based on the lesion size and MRI findings, and then the diagnostic performance was compared with that of conventional imaging criteria with logistic regression and a generalised estimating equation method. Results: A size cut-off value (>= 1.5cm diameter) and MRI findings of T-1 hypointensity, T-2 hyperintensity, DWI hyperintensity on both low and high b-value images (b=50 and 800s mm(-2), respectively), arterial enhancement, late washout and hepatobiliary hypointensity were selected as the diagnostic criteria. When lesions were considered malignant if they satisfied three or more of the above criteria, the sensitivity was significantly higher than when making a diagnosis based on arterial enhancement and washout alone (58.6% vs 13.8%, respectively; p=0.0002), while the specificity was 100.0% for both criteria. Conclusion: Our new diagnostic criteria on Gd-EOB-MRI may help to improve the discrimination of early HCC from benign hepatocellular nodules.