Differentiation of focal nodular hyperplasia from hepatocellular adenoma: Role of the quantitative analysis of gadobenate dimeglumine-enhanced hepatobiliary phase MRI.

PURPOSE: To determine the value of quantitative analysis of the hepatobiliary phase (HBP) in gadobenate dimeglumine (Gd-BOPTA)-enhanced magnetic resonance imaging (MRI) to differentiate focal nodular hyperplasia (FNH) from hepatocellular adenoma (HCA).

MATERIALS AND METHODS: Thirty-eight patients bearing 67 lesions (40 FNH; 27 HCA) were retrospectively included in this Institutional Review Board-approved study. The same volumetric interpolated breath-hold examination (VIBE) T1 -weighted sequences were performed before and after contrast injection on a 1.5T MRI, with HBP images acquired with a mean delay of 80 minutes (range 60-120 min). After a visual assessment of lesions enhancement (qualitative HBP analysis), the HBP signal intensity ratio (SIR) and the lesion-to-liver contrast enhancement ratio (LLCER) were calculated for each lesion by two observers (Mann-Whitney test). The sensitivities, specificities (receiver operating characteristic [ROC] curve analysis) and interobserver correlation (intraclass coefficient, ICC) of quantitative HBP analysis were determined.

RESULTS: All FNH and 44.4% of HCA appeared hyper- or isointense relative to the adjacent liver on qualitative HBP analysis. The mean SIR (P < 0.01) and LLCER (P < 0.0001) of FNH were significantly higher than that of HCA. The area under the ROC curve for the differentiation of FNH from HCA with LLCER was 0.98 for both observers. With a cutoff value of -0.3%-observer 1 with highest experience- LLCER assessment provided respective sensitivity and specificity values of 100% and 96.2% for the differentiation of FNH from HCA. The ICC was 0.7 for SIR measurements and 0.8 for LLCER measurements.

CONCLUSION: Quantitative LLCER assessment allows an accurate differentiation of FNH from HCA, even in hyper- or isointense HCA on HBP images.