FIGURE 1.
Irreversible 2-tissue-compartment model for 18F-FDG metabolism. Measured PET signal is combination of intracellular activity concentration of free 18F-FDG (nonmetabolized 18F-FDG in tissue), intracellular activity concentration of 18F-FDG-6-phosphate (metabolized 18F-FDG-6-PO4 in tissue), and fraction of activity concentration of 18F-FDG in blood plasma (Vb). By using dynamic PET/CT, pharmacokinetic rate-constants K1 and k2 (rate constants of transport of 18F-FDG into and out of tumor cell by glucose transporters, in mL/g/min), k3 (rate constant of cytoplasmic phosphorylation of 18F-FDG by hexokinase, per minute), and Vb (in milliliters of blood per milliliter of tumor) can be determined using nonlinear least-squares regression of dynamic PET/CT data. Vertical dashed line represents cell membrane