Background Hepatic epithelioid hemangioendothelioma (HEH) is extremely rare and the MRI features have never been investigated in a large group of patients. Methods A retrospective study was designed to review the MRI images of HEH patients. Two radiologists separately evaluated signal intensity (SI) on unenhanced imaging, morphological features, contrast-enhancement pattern at dynamic study. The MRI features were compared between patients with HEH and hepatic metastatic tumor (HMT). Results Fifty-seven HEH patients were included in this study and a total of 412 lesions were evaluated. On per-lesion analysis, the rate of coalescent lesion and subcapsular lesion were 18.2% and 39.8%, respectively. Capsular retraction and lollipop sign were observed in 47 lesions (11.4%) and 60 lesions (14.6%), respectively. Large lesions (> 5 cm) had the highest rate of coalescent lesion, subcapsular lesion, capsular retraction and lollipop sign. Target sign appeared in 196 lesions (47.6%) on T2 weighted (T2W) and 146 lesions (35.4%) on portal phase. Medium lesions (2–5 cm) had the highest rate of target sign on both T2W (72.9%) and portal phase (55.2%). On per-patient analysis, compare with HEH patients, HMT patients seldom had the appearance of lollipop sign (66.7% versus 6.4%, p < 0.01), capsular retraction (59.6% versus 3.2%, p < 0.01) and target appearance on both T2Wand portal phase (64.9% versus 12.7%, p < 0.01). Conclusion MRI features of HEH correlated with the lesion size. Capsular retraction, lollipop sign and coexistence of target sign on both T2W and portal phase were relatively specific MRI features of HEH, which could be helpful in suggesting the diagnosis.

Background Hepatic epithelioid hemangioendothelioma (HEH) is extremely rare, and CT features have never been analyzed in a large group of patients. Methods A retrospective study was designed to review the contrast-enhanced CT images of HEH patients. Intrahepatic lesions were categorized into three types: nodular, locally coalescent (coalescent lesion contained in one segment) or diffusely coalescent (coalescent lesion occupied more than one segment). CT features were compared among lesions of different sizes and patients with different lesion types. Results A total of 93 HEH patients were included in this study, and 740 lesions were analyzed. The results of per-lesion analysis showed that medium lesions (2–5 cm) had the highest rate of lollipop sign (16.8%) and target-like enhancement (43.1%), while lesions in large group (> 5 cm) had the highest rate of capsular retraction (38.8%) and vascular invasion (38.8%). The differences on enhancement pattern and the rates of lollipop sign and capsular retraction were significant among lesions of different sizes (p < 0.001, respectively). The results of per-patient analysis showed that patients in locally coalescent group had the highest rates of lollipop sign (74.3%) and target sign (94.3%). All patients in diffusely coalescent group had capsular retraction and vascular invasion. CT appearances of capsular retraction, lollipop sign, target sign and vascular invasion differed significantly among patients with different lesion types (p < 0.001, p = 0.005, p = 0.006 and p < 0.001, respectively). Conclusion CT features variated among HEH patients with different lesion types, and radiological appearances of HEH should be classified into nodular type, locally coalescent type and diffusely coalescent type.