The 2-tissue compartment model for FDG has the same structure as the standard model.

Differential Equation of the Mass Balance

with FDG concentration of in arterial plasma C_{p}(t), FDG concentration C_{1}(t) and phosphorylated FDG (FGD-6-P) concentration C_{2}(t) in tissue. K_{1} [ml/ccm/min] and k_{2} [1/min] are the uptake and clearance rate constants, whereas k_{3} [1/min] represents phosphorylation by hexokinase and k_{4} [1/min] dephosphorylation.

Operational Model Curve

with the concentration C_{B}(t) of tracer in whole blood, and the blood volume fraction v_{B}.

Parameter Fitting

The model includes the 5 fitable parameters **vB**, **K1**, **k2**, **k3**, **k4**. Usually, **vB** is fixed at a physiologic value of 3-5% to reduce the number of fitted parameters, and dephosphorylation is so slow that k_{4} is fixed **k4**=0.

FDG-specific Results

The FDG model has two additional input parameters, the lumped constant (**LC**) and the plasma glucose concentration (**PG** [mmol/l]). In combination with the estimated K_{1}, k_{2}, and k_{3} parameters they allow calculating the metabolic rate of glucose MRGlu

Note that the **LC** and **PG** values are maintained when switching back and forth with the **Patlak**** **model, if the **Model conversion** option in the **Extras **panel is enabled.