The applicability of total distribution volume (DV(t)) as an alternative to binding potential (BP) was investigated for neuroreceptor mapping by positron emission tomography (PET). BP is defined as a representative quantity of receptor density. However, for making parametric images of BP, a reference region where an aimed receptor has a very low density is assumed to exist in a target region such as the brain. Thus, if the kinetics of a radioligand for target receptors does not permit an appropriate reference region, BP imaging is unattainable. In this study, [(11)C]SA4503 PET is taken to be considered which has a high affinity to the sigma(1) receptors. Through a clinical investigation using wide ranges of physiological situations, ages, sex, diseases, and selective drug-loading conditions, DV(t) has a good linear relationship with BP, and the images can be used as a spatial distribution of sigma(1) density.