This ligand enables high-contrast imaging of diverse tau fibrils characteristic of both Alzheimer’s disease (AD) and non-AD tauopathies, including three repeat (3R) tau fibrils exemplified by PiD and four repeat (4R) tau fibrils observed in corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP). The gene discussed is MTA2; the disease is Alzheimer disease.