[11C] methionine and [18F] fluorodeoxyglucose PET in the follow-up of glioblastoma multiforme.
BACKGROUND
The aim of this study was to evaluate the value of [11C] methionine (MET) and [18F] fluorodeoxyglucose (FDG) PET in the follow-up of glioblastoma multiforme (GBM).


METHODS
After surgical and/or conservative treatment, 28 patients (pts) with GBM underwent FDG and MET PET on average 12.7 months after the diagnosis had been established. Scans were evaluated visually and by calculating the maximal tumor SUV as well as the ratio of tumor vs. contralateral region (RTu). The degree of tracer uptake was compared with survival time, disease duration and MRI findings.


RESULTS
The mean overall duration of survival was 12.7 months. The patients were divided into two groups: those that survived less than 12 months and those that survived longer than 12 months. Focally increased uptake was revealed by MET PET in 24 patients and by FDG PET in 2 patients. On MRI scans, viable tumor tissue was suspected in 18 patients. No correlations were registered between FDG/MET uptake and survival time or disease duration respectively; Kaplan-Meier calculations were negative in this regard. Similarly, negative results were obtained in subgroups of patients who had undergone microsurgical resection and whose disease was at least of 6 months' duration, and additionally in a subgroup who had undergone their last treatment longer than 6 months ago. With respect to survival groups, a positive MET PET was associated with a sensitivity of 86% and a specificity of 8%. SUV and RTu values did not differ between patients with positive or negative MRI results.


CONCLUSIONS
In this study FDG PET seems to be of limited value in the work-up of recurrent GBM because of its lower sensitivity than MET PET and the fact that it allows no prediction of the outcome. MET PET visualizes viable tumor tissue without adding any prognostic information and appears to be in no way superior to conventional imaging.
Pötzi
Christian
C
Department of Nuclear Medicine, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria.
Becherer
Alexander
A
Marosi
Christine
C
Karanikas
Georgios
G
Szabo
Monika
M
Dudczak
Robert
R
Kletter
Kurt
K
Asenbaum
Susanne
S
D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality; D002250:Carbon Radioisotopes; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D005909:Glioblastoma / Q000000981:diagnostic imaging* / Q000401:mortality; D006801:Humans; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging; D008297:Male; D008715:Methionine; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D015996:Survival Rate
D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D008715:Methionine