Novel Strategy for Diagnosis of Focal Nodular Hyperplasia Using Gadolinium Ethoxybenzyl Diethylenetriaminepentaacetic Acid: Enhanced Magnetic Resonance Imaging and Magnetic Resonance Elastography

Focal nodular hyperplasia (FNH) is the second most frequent benign liver tumor, and it is a fiber-rich stiff lesion. Typically, FNH can be diagnosed by imaging without biopsy. However, liver biopsy and diagnostic resection may be required to differentiate atypical FNH from other liver tumors, such as hepatocellular adenoma (HCA). Therefore, improved noninvasive diagnostic methods are needed. We experienced 2 cases where combination of magnetic resonance elastography (MRE) and gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) helped diagnose FNH. A 36-year-old woman and 17-year-old boy with liver tumors measuring 40 mm in diameter each showed hypointense nodule centers, indicating a central scar, surrounded by hyperintense signals during the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI. To rule out HCA, we performed MRE and liver biopsy. On MRE, the mean stiffness of the mass was 11.6 kPa (mean stiffness of the background liver was 1.7 kPa) and 11.1 kPa (mean stiffness of the background liver was 2.4 kPa) in the first and second patients, respectively. Histological examination of both specimens showed CK7-positive bile-ductular proliferations, abundant fibrous tissue, and few Ki-67-positive cells. Based on these results, we diagnosed these tumors as FNH. Combination of Gd-EOB-DTPA-enhanced MRI and MRE can evaluate the character and stiffness of lesion and help in the diagnosis of FNH.