This 3-tissue compartment model separates free tracer C_{1}(t) and non-specifically bound tracer C_{3}(t) in the non-displaceable compartment. K_{1} and k_{2} describe the exchange between arterial plasma and tissue, k_{3} and k_{4} between free and specifically bound tracer C_{2}(t) in tissue, and k_{5} and k_{6} between free and non-specifically bound tracer.

Differential Equation of the Mass Balance

with input curve C_{p}(t).

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 in principle includes the 7 fitable parameters **vB**, **K1**, **k2**, **k3**, **k4**, **k5**, **k6**, but reliable fitting cannot be achieved in practice. However, the model can be valuable for educational purposes and for generating simulation data.