title: Accumulation of (18)F-FDG in the liver in hepatic steatosis.
abstract: OBJECTIVE
  Nonalcoholic fatty liver disease is associated with hepatic inflammation. An emerging technique to image inflammation is PET using the glucose tracer, (18)F-FDG. The purpose of this study was to determine whether in hepatic steatosis the liver accumulates FDG in excess of FDG physiologically exchanging between blood and hepatocyte.
  
  
  METHODS
  Hepatic FDG uptake, as SUV = [voxel counts / administered activity] × body weight), and CT density were measured in a liver region in images obtained 60 minutes after injection of FDG in 304 patients referred for routine PET/CT. Maximum SUV (region voxel with the highest count rate, SUVmax) and average SUV ( SUVave) were measured. Blood FDG concentration was measured as the maximum SUV over the left ventricular cavity (SUVLV). SUVave was adjusted for hepatic fat using a formula equating percentage fat to CT density. Patients were divided in subgroups on the basis of blood glucose (< 4, 4 to < 5, 5 to < 6, 6 to < 8, 8 to < 10, and > 10 mmol/L). Hepatic steatosis was defined as CT density less than 40 HU (n = 71).
  
  
  RESULTS
  The percentage of hepatic fat increased exponentially with blood glucose. SUVmax / SUVLV and fat-adjusted SUVave / SUVLV but not SUVave / SUVLV correlated with blood glucose. Fat-adjusted SUVave was higher in patients with hepatic steatosis (p < 0.001) by ~0.4 in all blood glucose groups. There was a similar difference (~0.3) in SUVmax (p < 0.005) but no difference in SUVave. SUVmax / SUVLV and fat-adjusted SUVave / SUVLV correlated with blood glucose in patients with hepatic steatosis but not in those without. SUVave / SUVLV correlated with blood glucose in neither group.
  
  
  CONCLUSIONS
  FDG uptake is increased in hepatic steatosis, probably resulting from irreversible uptake in inflammatory cells superimposed on reversible hepatocyte uptake.
authors.affiliation: 1 Clinical Imaging Sciences Centre, University of Sussex, Falmer, Brighton BN1 9RR, UK.
authors.forename: Georgia
authors.initials: G
authors.lastname: Keramida
authors.forename: Jonathan
authors.initials: J
authors.lastname: Potts
authors.forename: Jan
authors.initials: J
authors.lastname: Bush
authors.forename: Sumita
authors.initials: S
authors.lastname: Verma
authors.forename: Sabina
authors.initials: S
authors.lastname: Dizdarevic
authors.forename: Adrien M
authors.initials: AM
authors.lastname: Peters
mesh_terms: D003198:Computer Simulation; D005234:Fatty Liver / Q000000981:diagnostic imaging*; D019788:Fluorodeoxyglucose F18 / Q000097:blood / Q000493:pharmacokinetics*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008099:Liver / Q000000981:diagnostic imaging* / Q000378:metabolism*; D008954:Models, Biological; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015854:Up-Regulation
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: FDG; PET; blood glucose; hepatic steatosis; liver