title: 2-[(18)F]Fluoro-2-deoxyglucose and glucose uptake in malignant gliomas before and after radiotherapy: correlation with outcome.
abstract: OBJECTIVE
  To examine whether quantitative 1-[(11)C]glucose- or 2-[(18)F]fluoro-2-deoxyglucose (FDG)-positron emission tomography performed before and/or after radiotherapy (RT) of malignant gliomas correlates with treatment outcome. Changes in metabolism between the start and finish of RT, and immediate post-RT studies have received little attention.
  
  
  METHODS
  Adults with malignant gliomas were imaged within 2 weeks before and/or 2 weeks after RT. Four patients were imaged only before RT, 12 only after RT, and 14 both before and after RT. Each 1-[(11)C]glucose and FDG study included arterial plasma sampling. Kinetic parameters, glucose metabolic rate (MRGlc), and FDG metabolic rate (MRFDG) were estimated by an optimization program based on a three compartment, four rate constant model. Changes in MRGlc or MRFDG from pre-RT to post-RT were calculated for the 14 patients studied at both times. Overall survival was examined, and survival was computed relative to historical controls in matched prognostic classes.
  
  
  RESULTS
  Low pre-RT MRGlc (P < 0.02) or MRFDG (P < 0.03), or an increase from pre- to post-RT in MRGlc (P < 0.004) or MRFDG (P < 0.006) are correlating with longer survival (4 patients still alive). Strikingly, the post-RT studies (n = 26) showed no correlation between MRGlc or MRFDG and survival (P = 0.73 and P = 0.46 respectively).
  
  
  CONCLUSIONS
  Low MRGlc or MRFDG before RT probably indicates less aggressive disease. An increase in MRGlc or MRFDG from pre- to post-RT in the tumors of patients with longer survival could be because of one or more of the following or other reasons: (a) apoptosis of tumor cells in response to RT requires energy; (b) decreased tumor cell density by the RT leaving normal cells with higher metabolism; or (c) inflammatory cells infiltrate and take up glucose or FDG where tumor cells are dying. Quantitative 1-[(11)C]glucose or FDG uptake in the early weeks post-RT correlates poorly with survival.
authors.affiliation: Department of Neurology, University of Washington School of Medicine, Seattle, Washington 98195, USA. aspence@u.washington.edu
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Spence
authors.forename: Mark
authors.initials: M
authors.lastname: Muzi
authors.forename: Michael M
authors.initials: MM
authors.lastname: Graham
authors.forename: Finbarr
authors.initials: F
authors.lastname: O'Sullivan
authors.forename: Jeanne M
authors.initials: JM
authors.lastname: Link
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Lewellen
authors.forename: Barbara
authors.initials: B
authors.lastname: Lewellen
authors.forename: Scott D
authors.initials: SD
authors.lastname: Freeman
authors.forename: David A
authors.initials: DA
authors.lastname: Mankoff
authors.forename: Janet F
authors.initials: JF
authors.lastname: Eary
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Krohn
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005910:Glioma / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000532:radiotherapy; D005947:Glucose / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D016019:Survival Analysis; D013997:Time Factors; D014055:Tomography, Emission-Computed; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose