MK-9470 is a selective, high-affinity, an inverse agonist for the cannabinoid CB1 receptor (CB1R) that has been developed for use in human brain imaging. Despite its moderately high lipophilicity, MK9470 shows good brain uptake and a high percentage of specific binding in the monkey brain. Radiolabeled MK-9470 has been used in the clinical setting to support CB1 receptor drug development for measuring receptor occupancy, to investigate CB1 receptor variability with gender and normal aging.