Cerebral glucose metabolism during pharmacologic studies: test-retest under placebo conditions.
The reliability of serial [18F]fluorodeoxyglucose (FDG) PET scans for psychopharmacologic studies was tested by using placebo infusions.


METHODS
FDG scans were obtained before and after a 30 min placebo infusion (n = 10; Group 1) or after each of two bolus infusions with placebo (n = 8; Group 2). Subjects performed a continuous performance task (CPT) during each scan. Cardiovascular measures and ratings of anxiety were obtained in all subjects. Samples for determination of plasma norepinephrine (NE) were taken at multiple time points in Group 1.


RESULTS
A slight increase in apparent global metabolism occurred between scans in both Groups 1 and 2. A few regions significantly increased in both groups. While an apparent increase in sympathetic activity occurred during the placebo infusion, neither NE levels, anxiety ratings nor cardiovascular measures correlated with global or regional FD6 uptake.


CONCLUSIONS
Test-retest differences of global and regional glucose metabolism were highly consistent across two experimental designs. While increases in cerebral glucose metabolism appeared to occur during the second scan, differences between scans were small. This method may offer advantages for selected psychopharmacologic studies.
Schmidt
M E
ME
Section on Clinical Pharmacology, National Institute of Mental Health, Bethesda, Maryland 20892, USA.
Ernst
M
M
Matochik
J A
JA
Maisog
J M
JM
Pan
B S
BS
Zametkin
A J
AJ
Potter
W Z
WZ
D000328:Adult; D001007:Anxiety / Q000378:metabolism; D001289:Attention Deficit Disorder with Hyperactivity / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D001921:Brain / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000378:metabolism*; D016022:Case-Control Studies; D003847:Deoxyglucose / Q000031:analogs & derivatives*; D003913:Dextroamphetamine / Q000494:pharmacology; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010919:Placebos; D015203:Reproducibility of Results; D013647:Task Performance and Analysis; D014055:Tomography, Emission-Computed
D005462:Fluorine Radioisotopes; D010919:Placebos; D019788:Fluorodeoxyglucose F18; D003847:Deoxyglucose; D005947:Glucose; D003913:Dextroamphetamine; D009638:Norepinephrine