Molecular imaging of the D2/3 receptor is widely used in neuropsychiatric research. Non-displaceable binding potential (BPND) is a very popular quantitative index, defined as the product of the receptor concentration (Bavail) and the radiotracer affinity for the receptor (1/appKd). As the appKd is influenced by parameters such as the endogenous neurotransmitter dynamics, it often constitutes a confounding factor in research studies. A simplified method for absolute quantification of both these parameters would be of great interest in this context. Here, we describe the use of a partial saturation protocol that permits to produce an in vivo Scatchard plot and thus estimate Bavail and appKd separately, through a single dynamic SPECT session. To validate this approach, a multi-injection protocol is used for the full kinetic modeling of [(123)I]IBZM using a 3-tissue compartment, 7-parameter model (3T-7k). Finally, more "classic" BPND estimation methods are also validated against the results of the 3T-7k.