Characteristics and distinguishing features of hepatocellular adenoma and focal nodular hyperplasia on gadoxetate disodium-enhanced MRI.

OBJECTIVE: The purpose of this study is to evaluate the performance of gadoxetate disodium-enhanced MRI in the characterization of focal nodular hyperplasia (FNH) and hepatocellular adenoma and to assess potential advantages of hepatocyte phase imaging in identifying features that distinguish FNH from hepatocellular adenoma.

MATERIALS AND METHODS: Gadoxetate disodium-enhanced MRI examinations of 12 patients with hepatocellular adenoma and 35 patients with FNH were retrospectively evaluated by three blinded readers. Diagnoses and confidence scores were recorded before and after disclosure of hepatocyte phase images. The data obtained were combined to create receiver operating characteristic curves, and the areas under the curves were compared. Imaging characteristics, including signal intensity, were recorded. Lesion-to-liver enhancement ratio was calculated for each contrast-enhanced phase.

RESULTS: The readers' average receiver operating characteristic area was significantly higher after disclosure of hepatocyte phase images (p=0.024). FNHs were correctly diagnosed in 74.3-97.1% of cases before and 97.1-100% of cases after the disclosure of hepatocyte phase images; hepatocellular adenoma was correctly diagnosed in 83-100% and 91.7-100% of cases (p>0.05). The presence of a central scar in FNH and fat on hepatocellular adenoma were the only morphologic features that were statistically significantly different (p<0.05). FNH had greater average contrast-enhanced signal intensity and enhancement ratio in all phases (p<0.001). A hepatocyte phase enhancement ratio of less than 0.7 was 100% specific and 91.6% sensitive for hepatocellular adenoma, with accuracy of 97.1% for these data.

CONCLUSION: Gadoxetate disodium-enhanced MRI had high accuracy in diagnosis of FNH and hepatocellular adenoma, and the hepatocyte phase improved their distinction. FNH enhances significantly more than hepatocellular adenoma. An enhancement ratio, particularly in the hepatocyte phase, can be potentially used as an additional distinguishing feature.