Magnetic resonance findings of hepatic epithelioid hemangioendothelioma: emphasis on hepatobiliary phase using Gd-EOB-DTPA
PURPOSE The aim of this study was to evaluate retrospectively magnetic resonance imaging (MRI) and (18)F fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) findings of hepatic epithelioid hemangioendothelioma (HEH). PATIENTS AND METHODS MRI and FDG PET/CT findings were reviewed in 6 patients with HEH confirmed by pathology. All patients underwent magnetic resonance (MR) examination. Early PET/CT scans were performed 1 hour after FDG injection in all 6 patients. After an interval of 1 hour, delayed PET/CT scans were performed in 4 patients. RESULTS A total of 60 lesions were detected in all 6 patients. MRI features of HEH included multifocal hepatic disease, predominantly subcapsular location, coalescence of lesions, and capsular retraction. T2-weighted MR images frequently showed a target-like configuration of the lesions. Contrast-enhanced MR images showed variable degrees of peripheral rim enhancement with delayed central enhancement. Forty lesions (67%) with increased FDG uptake and 20 lesions (33%) with FDG uptake similar to the surrounding liver parenchyma were found in all 6 patients. The mean maximum standardized uptake value (SUV(max)) of all lesions was 3.6 ± 1.1, with a low variability of SUV(max) among lesions ranging from 1.7 to 6.6. There was no relationship between lesion sizes and corresponding SUV(max). Some larger lesions demonstrated a hypermetabolic peripheral rim reflecting hypercellular tumor regions and a relatively hypometabolic central area corresponding to hypocellular stroma. Eleven lesions with increased FDG uptake on the delayed PET/CT images were found in 3 patients, and 19 lesions with decreased FDG uptake were found in all 4 patients with total 32 lesions. CONCLUSIONS MRI demonstrated morphological features of HEH and FDG PET/CT reflected the histopathological composition of the tumors. FDG uptake of HEH may be related to tumor cellularity, but not the tumor size. Dual-time-point imaging may be not useful for differentiating benign lesions from HEH. Familiarity with the morphological and functional imaging findings of HEH is useful for recognition of this rare hepatic tumor.