title: Focal liver lesions: pattern-based classification scheme for enhancement at arterial phase CT.
abstract: OBJECTIVE
  To present our early experience with a classification scheme for categorizing focal liver lesions on the basis of the enhancement patterns that they exhibit in the arterial phase of computed tomography (CT) and to determine whether particular enhancement patterns suggest particular diagnoses.
  
  
  METHODS
  The authors reviewed arterial phase CT images in 100 consecutive patients with focal liver lesions, excluding simple cysts. The enhancement pattern of the dominant or representative lesion in each patient was classified into one of five categories-homogeneous, abnormal internal vessels or variegated, peripheral puddles, complete ring, or incomplete ring-by three radiologists blinded to the proved diagnosis. Lesions without enhancement were recorded separately. Agreement was reached by consensus in all cases. Standards of reference included findings at histologic examination, correlative imaging, or clinical and imaging follow-up.
  
  
  RESULTS
  Ninety-two percent of the 100 lesions demonstrated arterial phase enhancement. Patterns associated with positive predictive values of 82% or greater and specificity of 80% or greater included abnormal internal vessels or variegated (hepatocellular carcinoma), peripheral puddles (hemangioma), and complete ring (metastasis).
  
  
  CONCLUSIONS
  The appearance of hepatic lesions in the arterial phase of enhancement has potential use in the determination of specific diagnoses. The classification scheme used in this study may be a useful tool for the interpretation of arterial phase CT studies.
authors.affiliation: Department of Radiology, Stanford University Medical Center, CA, USA. ninomurcia@forsythe.stanford.edu
authors.forename: M
authors.initials: M
authors.lastname: Nino-Murcia
authors.forename: E W
authors.initials: EW
authors.lastname: Olcott
authors.forename: R B
authors.initials: RB
authors.lastname: Jeffrey
authors.forename: R L
authors.initials: RL
authors.lastname: Lamm
authors.forename: C F
authors.initials: CF
authors.lastname: Beaulieu
authors.forename: K A
authors.initials: KA
authors.lastname: Jain
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001158:Arteries; D006528:Carcinoma, Hepatocellular / Q000145:classification / Q000000981:diagnostic imaging* / Q000556:secondary; D005260:Female; D020518:Focal Nodular Hyperplasia / Q000145:classification / Q000000981:diagnostic imaging*; D006391:Hemangioma / Q000145:classification / Q000000981:diagnostic imaging*; D006801:Humans; D008099:Liver / Q000098:blood supply / Q000000981:diagnostic imaging*; D008113:Liver Neoplasms / Q000145:classification / Q000000981:diagnostic imaging* / Q000556:secondary; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000145:classification / Q000295:instrumentation / Q000379:methods*