To improve the measurements of glucose metabolism in the human brain, we imposed biologic constraints on the deoxy-glucose model with and without dephosphorylation of FDG-6-phosphate (the k*/4- and k*/3-models). The constraints included constant transport and phosphorylation ratios (τ and φ) and a common partition volume (K1/k2) for tracer [18F]FDG and glucose. In the presence of significant dephosphorylation, the k*/3-model yielded time-dependent estimates of the phosphorylation coefficient (k*/3), while the k*/4-model yielded time-independent estimates. However, the two models yielded practically identical measurements of regional cerebral glucose metabolism in PET studies of six normal volunteers when the phosphorylation affinity ratio (the k*/3/k3 ratio of FDG and glucose) and tracer circulation time were 0.30 and 20 min for the k*/3-model and 0.33 and 45 min for the k*/4-model.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Nuclear Medicine|
|State||Published - Jan 1 1991|
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging