MAPT and supranuclear palsy, progressive, 1: Potentially the most clinically relevant “off-target” binding regions are the substantia nigra (for confounding of red nucleus tau binding in PSP), the lateral geniculate binding in hippocampal Braak tangle staging, subpial melanin-containing structures, and the choroid plexus or vascular structures when closely associated with the hippocampus or other Braak-important regions.