title: Imaging features of small hepatocellular carcinomas with microvascular invasion on gadoxetic acid-enhanced MR imaging.
abstract: OBJECTIVE
  Detection of hepatocellular carcinomas (HCCs) before microvascular invasion (MVI) occurs is important due to the poor outcomes associated with MVI. We retrospectively investigated the imaging features of small HCCs with MVI on gadoxetic acid-enhanced MR imaging.
  
  
  METHODS
  Fifty patients (40 men and 10 women; mean age, 54 years) with 58 surgically proven small (2 cm or less) HCCs were evaluated by gadoxetic acid-enhanced MRI. Signal intensities on imaging sequences and the presence of the typical dynamic enhancement pattern (arterial enhancement and washout) were assessed. Fisher's exact tests were performed to evaluate the relationships between the presence of MVI, tumor size, and imaging findings.
  
  
  RESULTS
  None of the 12 small HCCs with diameters of 1cm or less had MVI, while 15 (33%) of the 46 small HCCs with diameters of 1.1-2.0 cm had MVI (p=0.025, Fisher's exact test). Among the small HCCs with diameters of 1.1-2.0 cm, all HCCs with MVI showed the typical dynamic pattern and hyperintensity on T2- and diffusion-weighted images. Most HCCs (54 lesions, 93%) were hypointense on hepatobiliary phase images regardless of the presence of MVI.
  
  
  CONCLUSIONS
  All small HCCs with MVI showed typical dynamic pattern and hyperintensity on T2-weighted and diffusion-weighted images, while atypical dynamic pattern and size of less than 1cm in diameter may suggest absence of MVI.
authors.affiliation: Department of Radiology and Research Institute of Radiological Science, Yonsei University Severance Hospital, Seoul, South Korea. kimnex@yuhs.ac
authors.forename: Myeong-Jin
authors.initials: MJ
authors.lastname: Kim
authors.forename: Myungsu
authors.initials: M
authors.lastname: Lee
authors.forename: Jin-Young
authors.initials: JY
authors.lastname: Choi
authors.forename: Young Nyun
authors.initials: YN
authors.lastname: Park
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000150:complications / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008113:Liver Neoplasms / Q000150:complications / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D055806:Microvessels / Q000473:pathology*; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009389:Neovascularization, Pathologic / Q000209:etiology / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA