Tau ligand binding patterns in progressive supranuclear palsy. (Left) Typical 2-(1-(6-((2-[18F]fluoroethyl) (methyl)amino)-2-naphthyl)ethylidene) malononitrile ([18F]-FDDNP) binding patterns seen in advanced progressive supranuclear palsy (PSP), early PSP and Parkinson’s disease. [18F]-FDDNP signal due to tau binding seen in the basal ganglia, midbrain and pons in PSP subjects but not in Parkinson’s disease. (Right) Sagittal magnetic resonance imaging (MRI) scan of a PSP patient with characteristic midbrain atrophy. DVR, distribution volume ratio, a scaled measure that indicates the linear function of radioligand binding. Reprinted with permission from .