The PKIN tool allows the simultaneous fitting of the shape parameters of the blood models and the kinetic parameters of the tissue model. This fitting mode can be activated by checking the Fit blood box on the Extras pane. It is active in the fitting of the single tissue TAC as well as in coupled fitting.
With Fit blood on, ALL parameters of the Whole blood and the Plasma model (but not the plasma fraction or parent fraction parameters) which have the fit check on will be modified during the fit of the kinetic tissue model. Note that the blood models are not fitted to the actual blood measurements in this process, but it is only the impact of the blood curve on the calculated tissue model curves which results in the modification of the blood model parameters.