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Coupled Fitting

In some situations prior knowledge can help to improve the stability of fitting. In receptor experiments it may be adequate to assume that the distribution volume (K1/k2) of the non-displaceable compartment and/or the dissociation rate from specific binding sites (k4) are equal in different tissues of the brain. Hence, a fit can be performed which finds a separate K1 and k3 for each regional TAC, but which delivers a K1/k2 and k4 common across the regions.

In PKIN this task can be achieved with a coupled fit. The requirements are:

Given these requirements, the user specifies the coupled fit configuration on the Coupled pane:

Coupled Fitting

In the upper section the kinetic model parameters are listed. Check those parameters which are to be coupled among regions. The lower section lists all selectable regional TACs (having the same model). Check all regions which are to be included in coupled fitting.

Fit coupled starts the fitting process as follows:

Note: Coupled fitting may take significant processing time. Thus the Batch mode facility may be a helpful option to run such jobs at less busy times.