Comparison of different quantification methods for (18)F-fluorodeoxyglucose-positron emission tomography studies in rat brains

OBJECTIVES: This study aimed to evaluate several methods to estimate glucose consumption in the male Wister rat brain as measured by PET. METHODS: Fourteen male Wistar normoglycemic rats were studied. The input function consisted of seventeen blood samples drawn manually from the femoral artery. Glucose uptake values were calculated using the input function resulting from the arterial blood samples and the tissue time-activity curve derived from the PET images. The estimated glucose consumption rate (K(i)) based on the 2-tissue compartment model (2TCM) served as the standard for comparisons with the values calculated by the Patlak analysis and with the fractional uptake rate (FUR), standardized uptake value (SUV) and glucose corrected SUV (SUV(glu)). RESULTS: No significant difference between the standard K(i) and the Patlak K(i) was observed. The standard K(i) was also found to have strong correlations and concordance with the K(i) value estimated by the Patlak analysis. The FUR method presented an excellent correlation with the K(i) value obtained by the 2TCM/Patlak analyses, in contrast to the SUV or SUV(glu). CONCLUSIONS: From a methodological point of view, the present findings confirm the theoretical limitations of the cerebral SUV and SUV(glu) as a substitute for K(i) in the estimation of glucose consumption in the brain. Our data suggest that the FUR is the surrogate to K(i).