This model has been developed by Rizzo et al.  for the analysis of [11C]-PBR28 uptake in the human brain. In addition to the compartments in the standard 2-tissue compartment model, a compartment Cvasc was introduced which represents slow binding of the tracer to the endothelium of the vasculature.
Differential Equation of the Mass Balance
with input curve Cp(t).
Operational Model Curve
with the concentration CB(t) of tracer in whole blood, and the blood volume fraction vB.
The model includes the 6 fitable parameters vB, K1, k2, k3, k4, Kb. Usually, vB is fixed at a physiologic value of 3-5%. The default initial parameter values are the ones which were used for PBR28.
1.Rizzo G, Veronese M, Tonietto M, Zanotti-Fregonara P, Turkheimer FE, Bertoldo A. Kinetic modeling without accounting for the vascular component impairs the quantification of [(11)C]PBR28 brain PET data. J Cereb Blood Flow Metab. 2014;34(6):1060-9. DOI