title: Diagnostic criteria for fatty infiltration of the liver on contrast-enhanced helical CT.
abstract: OBJECTIVE
  The purpose of the study was to develop quantitative and qualitative criteria for diagnosing fatty liver on contrast-enhanced helical CT.
  
  
  METHODS
  Differential liver-spleen attenuation was evaluated between 80 and 120 sec after injection in 76 patients who underwent contrast-enhanced helical CT. Unenhanced CT images had earlier established fatty liver when the liver minus spleen attenuation difference was less than or equal to -10 H (n = 18). Four observers who had not seen the unenhanced images used contrast-enhanced CT images to assess the presence of fatty liver on a five-point Likert scale, the presence of geographic areas spared from fatty infiltration, and the relative liver-spleen attenuation. The diagnostic accuracies of various imaging criteria were compared using McNemar's chi-square test (for sensitivity and specificity) and analysis of receiver operating characteristic curves.
  
  
  RESULTS
  Sensitivity, specificity, and receiver operating characteristic curve areas for observers' qualitative judgments were 54%, 95%, and .91, respectively; for quantitative differential liver-spleen attenuation (80-100 sec; -20.5 H discriminatory value), the values were 86%, 87%, and .94, respectively; and for quantitative differential liver-spleen attenuation (101-120 sec; -18.5 H discriminatory value), the values were 93%, 93%, and .98, respectively. Differential liver-spleen attenuation was time-dependent; overlap was noted between healthy subjects and patients with fatty liver. Qualitatively, geographic sparing was highly specific (94%) for fatty liver, whereas liver attenuation greater than or equal to spleen attenuation excluded fatty liver in all but one case.
  
  
  CONCLUSIONS
  Although quantitative and qualitative criteria for diagnosing fatty liver on helical CT can be determined, they are protocol-specific. Limited unenhanced hepatic CT remains the optimal technique for detection of fatty infiltration of the liver.
authors.affiliation: Department of Radiology, University of Pennsylvania Medical Center, Philadelphia 19104, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Jacobs
authors.forename: B A
authors.initials: BA
authors.lastname: Birnbaum
authors.forename: M A
authors.initials: MA
authors.lastname: Shapiro
authors.forename: C P
authors.initials: CP
authors.lastname: Langlotz
authors.forename: F
authors.initials: F
authors.lastname: Slosman
authors.forename: S E
authors.initials: SE
authors.lastname: Rubesin
authors.forename: S C
authors.initials: SC
authors.lastname: Horii
mesh_terms: D003287:Contrast Media; D005234:Fatty Liver / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007482:Iothalamate Meglumine; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007482:Iothalamate Meglumine