title: Glucose-normalized standardized uptake value from (18)F-FDG PET in classifying lymphomas.
abstract: Our objective was to derive the best glucose sensitivity factor (g-value) and the most discriminating standardized uptake value (SUV) normalized to glucose for classifying indolent and aggressive lymphomas.
  
  
  METHODS
  The maximum SUV obtained from (18)F-FDG PET over the area of biopsy in 102 patients was normalized by serum glucose ([Glc]) to a standard of 100 mg/dL. Discriminant analysis was performed by using each SUV(100) (SUV x {100/[Glc]}(g), calculated using various g-values ranging from -3.0 to 0, one at a time) as a variable against the lymphoma grades, and plotting the percentage of correct classifications against g (g-plot) to search for the best g-value in normalizing SUV(100) for classifying grades. To address the influence of the extreme glucose conditions, we repeated the same analyses in 12 patients with [Glc] < or = 70 mg/dL or [Glc] > or = 110 mg/dL.
  
  
  RESULTS
  SUV(100) correctly classified lymphoma grades ranging from 62% to 73% (P < 0.0005), depending on the g-value, with a maximum at a g-value of -0.5. For the subgroup with extreme glucose values, the g-plot also revealed higher and more optimal discrimination at a g-value of -0.5 (92%) than at a g-value of 0 (83%) (P = 0.03). The discrimination deteriorated at g < -1 in both analyses. The box plot for all cases using a g-value of -0.5 showed little overlap in classifying lymphoma grades. For a visually selected threshold SUV(100) of 7.25, the sensitivity, specificity, and accuracy of identifying aggressive grades were 82%, 79%, and 81%, respectively.
  
  
  CONCLUSIONS
  The results suggest that metabolic discrimination between lymphoma grades using a glucose-normalized SUV from (18)F-FDG PET is improved by introducing g-value as an extra degree of freedom.
authors.affiliation: Nuclear Medicine, William Beaumont Hospital, Royal Oak, Michigan 48073, USA. owong@beaumont.edu
authors.forename: Ching-Yee Oliver
authors.initials: CY
authors.lastname: Wong
authors.forename: Joseph
authors.initials: J
authors.lastname: Thie
authors.forename: Kelly J
authors.initials: KJ
authors.lastname: Parling-Lynch
authors.forename: Dana
authors.initials: D
authors.lastname: Zakalik
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Margolis
authors.forename: Marianne
authors.initials: M
authors.lastname: Gaskill
authors.forename: Jack
authors.initials: J
authors.lastname: Hill
authors.forename: Feng
authors.initials: F
authors.lastname: Qing
authors.forename: Darlene
authors.initials: D
authors.lastname: Fink-Bennett
authors.forename: Conrad
authors.initials: C
authors.lastname: Nagle
mesh_terms: D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005947:Glucose / Q000378:metabolism*; D006689:Hodgkin Disease / Q000145:classification / Q000000981:diagnostic imaging* / Q000378:metabolism*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods* / Q000592:standards; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose