PKIN Reference > Compartment Models > List of PKIN Compartment Models

PKIN features a comprehensive set of compartment models as listed below. The number of tissue compartments ranges from 1 to 3. There are different variants of the same model structure, so that prior information can be entered easily, and that coupling of physiologic parameters across region is possible.

For instance, the 2-tissue compartment model has the standard parameters K1, k2, k3, k4 . An equivalent description is by the parameters K1, K1/k2, k3, k4 . The advantage is, that the K1/k2, represents the distribution volume of the non-displacement compartment in tissue (free and non-specifically bound tracer), which can often be assumed to be the same across different tissues. Therefore, K1/k2 can be included as a common parameter in a coupled fit, hereby reducing the number of fitted parameters and thus potentially improving the identifiability of all.

Model Name	Description
1-Tissue Compartment	Most basic compartment model with the plasma compartment and one tissue compartment.
2-Tissue Compartments	Compartment model with the plasma compartment and two sequential tissue compartments. Often used for receptor studies.
FDG-2 Tissue Compartments	The 2-Tissue compartment model including the plasma glucose and the lumped constant to calculate the metabolic rate of glucose.
2-Tissue Compartments, K1/k2	The same model as the 2-Tissue compartment model, except that K1/k2 is used as a model parameter instead of k2. This facilitates coupled fitting.
2-Tissue Compartments, K1/k2 &Vs 2-Tissue Compartments, K1/k2 &Vt	The same models as the 2-Tissue compartment model, except that K1/k2 and the specific or total distribution volumes are used as model parameters instead of k2 and k4. This facilitates coupled fitting and the easy generation of synthetic model curves.
Linear Least Squares	2-Tissue Compartment model solved by the Linear Least Squares method.
2-Tissue Compartments, k5	2-Tissue compartment model with an efflux from the last compartment.
2-Tissue Compartments, Bmax	Non-linear 2-Tissue compartment model for receptor tracer studies accounting for the saturation of receptor sites.
2-Tissue Compartments, K1/k2, Bmax	Same model as above, but using K1/k2 as fitting parameter instead of k2.
2-Tissue Compartments, vascular trapping	2-Tissue compartment model with an additional endothelial trapping compartment.
Irreversible 2-Tissue Irreversible 2-Tissue, Flux Irreversible 2-Tissue, K1/k2, Flux	In principle the same models as the 2-Tissue compartment model with k4=0. The Flux variants allow using the influx as a fitting parameter, or as a fixed parameter set to the result of a Patlak analysis. When using K1/k2 also as a fitting parameter, coupled fitting can be employed.
3-Tissue Compartments	Compartment model which separates free tracer in tissue from non-specific binding.
3-Tissue Compartments, K1/k2, Vs	As above, but using but using K1/k2 and the specific distribution volume as fitting parameters.
3-Tissue Compartments, sequential	Model with three sequential compartments originally developed for FDG uptake in skeletal muscle.
Flow & Dispersion	Specific model for dynamic H215O- PET Data with implicit deconvolution of the input curve dispersion
3-Tissue Compartments, Metabolites	Extends the 2 tissue compartment model by a metabolite compartment with a second input curve of labeled metabolites from the plasma.
3-Tissue Compartments, Metabolites, K1/k2 3-Tissue Compartments, Metabolites, K1/k2, Vs	As above, but using but using K1/k2 and the specific distribution volume as fitting parameters.
4-Tissue Compartments, Metabolites, K1/k2	Two parallel 2-compartment models for authentic ligand and metabolites, linked by a transfer constant between the non-specific compartments.
Triple-injection Protocol for Flumazenil	During a single imaging study three injections are applied: hot ligand first, then cold ligand for displacement, then a mixture of cold & hot ligand. The individual receptor parameters can be estimated.