K (Patlak Ref): Patlak Reference Plot for FDOPA

The K (Patlak Ref) model is exactly the same model as the standard Patlak model, except that the blood activity is replaced by the activity of a reference TAC devoid of trapping [29]:

In this situation the slope K of the plot equals

with an equilibrium constant K_eq.

This model is often used to calculate an index K_occ of the FDOPA influx using an occipital TAC as the reference [30].