Fig. 3

The ratio of radioactivity in the CP (a high-binding VOI) or VTA (a low-binding VOI) to the radioactivity in the Cer (the reference region), as estimated on the basis of a simulated partial saturation experiment, for various masses of injected unlabeled ligand. At time-points beyond 70-min post radiotracer injection, this ratio is around 1 in the CP and 0.4 in the VTA. This ratio is relatively temporally stable at the time points employed in the Scatchard plot quantification with the partial saturation approach