MAPT and Alzheimer disease: At the present time, three amyloid tracers ([18F]florbetapir, [18F]florbetaben, and [18F]flutemetamol) have received regulatory approval for the purposes of estimating amyloid β neuritic plaque density in adult patients being evaluated for AD and other causes of cognitive decline, and one tau tracer ([18F]flortaucipir) is FDA-approved for the purposes of estimating the density and distribution of aggregated tau NFTs in patients with cognitive impairments who are being evaluated for AD.