The FDG lumped constant in normal human brain.
The lumped constant (LC) is a correction factor used to infer glucose metabolic rate (MR(glc)) from FDG metabolic rate (MR(FDG)).


METHODS
LC was determined in normal brain in 10 subjects (4 male, 6 female) by measuring regional MR(glc) and MR(FDG) independently using 1-(11)C-glucose and (18)F-FDG with dynamic positron tomographic imaging, arterial blood sampling, and region-of-interest time-activity curve analysis with appropriate compartmental models.


RESULTS
The mean LC (+/-SD) for normal brain was found to be 0.89 +/- 0.08. The value for cerebellum was slightly lower, 0.78 +/- 0.11 (P = 0.006; 2-tailed paired t test).


CONCLUSIONS
The LC values determined in this study are considerably higher than older values in the literature, probably because of methodologic differences, but agree with a recent study by Hasselbalch.
Graham
Michael M
MM
Division of Nuclear Medicine, Department of Radiology, University of Iowa, Iowa City, Iowa 52242, USA. michael-m-graham@uiowa.edu
Muzi
Mark
M
Spence
Alexander M
AM
O'Sullivan
Finbarr
F
Lewellen
Thomas K
TK
Link
Jeanne M
JM
Krohn
Kenneth A
KA
D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D002250:Carbon Radioisotopes; D005260:Female; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D012016:Reference Values; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose