title: The FDG lumped constant in normal human brain.
abstract: The lumped constant (LC) is a correction factor used to infer glucose metabolic rate (MR(glc)) from FDG metabolic rate (MR(FDG)).
  
  
  METHODS
  LC was determined in normal brain in 10 subjects (4 male, 6 female) by measuring regional MR(glc) and MR(FDG) independently using 1-(11)C-glucose and (18)F-FDG with dynamic positron tomographic imaging, arterial blood sampling, and region-of-interest time-activity curve analysis with appropriate compartmental models.
  
  
  RESULTS
  The mean LC (+/-SD) for normal brain was found to be 0.89 +/- 0.08. The value for cerebellum was slightly lower, 0.78 +/- 0.11 (P = 0.006; 2-tailed paired t test).
  
  
  CONCLUSIONS
  The LC values determined in this study are considerably higher than older values in the literature, probably because of methodologic differences, but agree with a recent study by Hasselbalch.
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, University of Iowa, Iowa City, Iowa 52242, USA. michael-m-graham@uiowa.edu
authors.forename: Michael M
authors.initials: MM
authors.lastname: Graham
authors.forename: Mark
authors.initials: M
authors.lastname: Muzi
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Spence
authors.forename: Finbarr
authors.initials: F
authors.lastname: O'Sullivan
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Lewellen
authors.forename: Jeanne M
authors.initials: JM
authors.lastname: Link
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Krohn
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D002250:Carbon Radioisotopes; D005260:Female; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D012016:Reference Values; D014055:Tomography, Emission-Computed
chemical_list: D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose