Magnetic resonance findings of hepatic epithelioid hemangioendothelioma: emphasis on hepatobiliary phase using Gd-EOB-DTPA

Purpose: To examine the characteristic features of hepatic epithelioid hemangioendothelioma (HEH) on magnetic resonance imaging (MRI) using Gd-EOB-DTPA. Material and methods: Twelve patients (mean age, 50 years; male:female = 6:6) who were pathologically confirmed to have HEH in two tertiary institutions were retrospectively investigated. For qualitative analysis, the MRI features of HEH including core pattern were characterized, and lesions were divided into core and non-core groups. For quantitative analysis, standardized mean signal intensities (SI_st) measured at the tumor center, periphery, and liver parenchyma were plotted against the dynamic phases. Differences in SI_st between the core and non-core group were calculated for the tumor center and periphery. We also examined the radiologic and pathologic correlation for cases in which surgical resection was performed. Results: Forty-seven nodules in 12 patients were analyzed. The mean size of the lesions was 2.9 ± 1.0 cm. In the per-lesion analysis, ring-like arterial enhancement (74%) on arterial phase was the most frequent feature, followed by core pattern (51%), and hyperintense rim on T1-weighted imaging (43%). In the per-patient analysis, capsular retraction (75%) was the most common sign. The percentage of patients with core pattern was 58%. In the core group, the SI_st of the center showed slow enhancement starting from the transitional phase, resulting in divergence between the two graphs throughout the entire dynamic study (p < 0.05). Pathologically, the lesion center consisted of reduced cellularity with myxohyaline stroma and necrosis. Conclusion: Core pattern can be considered a new diagnostic sign of HEH.