title: CT and MR imaging findings of hepatic epithelioid hemangioendotheliomas: emphasis on single nodular type.
abstract: OBJECTIVE
  To evaluate imaging findings of hepatic epithelioid hemangioendothelioma (HEH), with emphasis on solitary form at the initial presentation.
  
  
  METHODS
  Ten cases of pathologically confirmed HEH were retrospectively reviewed; seven patients had CT and MR images and three had only CT images. Two radiologists assessed the followings in consensus: lesion number, size, location, presence of capsular retraction and calcification, attenuation, signal intensity, and enhancement pattern.
  
  
  RESULTS
  Initially, HEHs manifested as a single mass (n = 5) or multiple masses (n = 5). One case demonstrated a solitary nodule at first, which subsequently transformed to multifocal nodules on serial follow-up. The maximal diameter of the lesions ranged from 1.8 to 10 cm (mean 4.2 cm). All cases showed predominant subcapsular location. Capsular retraction was seen in multinodular types, but not in solitary types. Two patients had intra-lesional calcifications. HEHs showed minimal enhancement (7/7 patients) on the hepatic arterial phase CT and rim-like enhancement (5/10 patients), minimal enhancement (2/10 patients), multilayered target enhancement (2/10 patients), and peripheral nodular enhancement (1/10 patients) on the portal venous phase CT. On MR images (n = 7), HEHs showed hypointensity on T1-weighted images and hyperintensity on T2-weighted images. Dynamic contrast-enhanced MR images revealed progressive centripetal fill-in enhancement (7/7 patients). On Gd-EOB-DTPA-enhanced hepatobiliary phase images, HEH manifested as homogeneous hypointensity (3/5 patients) and target-shaped hypointensity (2/5 patients).
  
  
  CONCLUSIONS
  HEH can manifest as single nodular, multinodular, or diffuse type. Common imaging features of HEH are multiple subcapsular nodules with coalescence, capsular retraction, peripheral, and delayed enhancement. However, HEH can manifest as a solitary subcapsular mass with minimal or rim-like enhancement at early phase and progressive centripetal fill-in enhancement during dynamic phase imaging, representing early stage of HEH. A single nodular type can progress to multifocal nodular type during follow-up.
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 222, Banpo-daero, Seocho-gu, Seoul, 137-701, Republic of Korea.
authors.forename: Eu Hyun
authors.initials: EH
authors.lastname: Kim
authors.forename: Sung Eun
authors.initials: SE
authors.lastname: Rha
authors.forename: Young Joon
authors.initials: YJ
authors.lastname: Lee
authors.forename: Ie Ryung
authors.initials: IeR
authors.lastname: Yoo
authors.forename: Eun Sun
authors.initials: ES
authors.lastname: Jung
authors.forename: Jae Young
authors.initials: JY
authors.lastname: Byun
mesh_terms: D000368:Aged; D005260:Female; D018323:Hemangioendothelioma, Epithelioid / Q000175:diagnosis*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008113:Liver Neoplasms / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed