2-[(18)F]Fluoro-2-deoxyglucose and glucose uptake in malignant gliomas before and after radiotherapy: correlation with outcome.
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.
Spence
Alexander M
AM
Department of Neurology, University of Washington School of Medicine, Seattle, Washington 98195, USA. aspence@u.washington.edu
Muzi
Mark
M
Graham
Michael M
MM
O'Sullivan
Finbarr
F
Link
Jeanne M
JM
Lewellen
Thomas K
TK
Lewellen
Barbara
B
Freeman
Scott D
SD
Mankoff
David A
DA
Eary
Janet F
JF
Krohn
Kenneth A
KA
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
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose