MCIDAS and Alzheimer disease: For quantitative imaging of MC-I activity in the living animal brain, we previously developed a positron emission tomography (PET) probe, 2-tert-butyl-4-chloro-5-{6-[2-(2-18F-fluoroethoxy)-ethoxy]pyridin-3-ylmethoxy}-2H-pyridazin-3-one (18F-BCPP-EF) [16], and evaluated its ability to detect age-related reductions in MC-I activity in the brains of monkeys [17] and humans [18]; neurodegenerative damage after ischaemia–reperfusion injury in the brains of live rats [19] and monkeys [20]; and Alzheimer’s disease-related reductions in MC-I activity in the brains of monkeys [21] and humans [22].