Sagittal (Top row), and trans-axial (Middle and Bottom rows) views of VT images of [18F]ASEM in the same baboon for a baseline PET scan (B), and after administration of 0.5 mg/kg (C) and 5 mg/kg (D) of SSR180711, a selective α7-nAChR partial agonist. MR images (A) indicate locations of selected brain structures including the cingulate cortex (Cg), thalamus (Th), and caudate nucleus (CN), which are indicated by + in the VT images (D). The VT images are displayed using the same minimum and maximum values for all scanning conditions. These data demonstrate the dose dependent blockade of [18F]ASEM in baboon brain and provide evidence that [18F]ASEM is specific and mediated by α7-nAChR. The images also suggest that there is no reference region devoid of α7-nAChRs. Reprinted from[59] with permission of SNMMI.