Journal of nuclear medicine : official publication, Society of Nuclear Medicine
-
Neuroreceptor imaging in the nonhuman primate (NHP) is valuable for translational research approaches in humans. However, most NHP studies are conducted under anesthesia, which affects the interpretability of receptor binding measures. The aims of this study were to develop awake NHP imaging with minimal head restraint and to compare in vivo binding of the γ-aminobutyric acid type A (GABAA)-benzodiazepine radiotracer (11)C-flumazenil under anesthetized and awake conditions. We hypothesized that (11)C-flumazenil binding potential (BPND) would be higher in isoflurane-anesthetized monkeys. ⋯ We successfully performed awake NHP imaging with minimal head restraint. There was close agreement in (11)C-flumazenil BPND values between awake and anesthetized conditions.
-
PET is used to image active inflammatory processes by targeting the translocator protein (TSPO). In vitro, second-generation TSPO radioligands, such as PBR111, have been shown to bind to human tissue samples with either high affinity (high-affinity binders, HABs), low affinity (low-affinity binders, LABs), or an intermediate, mixed affinity (mixed-affinity binders, MABs). We previously explained these differences in affinity in human tissue via the rs6971 polymorphism in the TSPO gene and predicted that the specific signal from PET ligands in vivo would vary accordingly. In silico modeling predicted that (18)F-PBR111 would have a moderate to high specific-to-nonspecific ratio in the normal human brain. To test these predictions, we present here the analysis and modeling of (18)F-PBR111 data in healthy humans. ⋯ (18)F-PBR111 shows a high specific signal in the healthy human brain in vivo. A large component of the variability in the signal across subjects is explained by genetic variation and age, indicating that (18)F-PBR111 can be used for the quantitative assessment of TSPO expression.