PET-amyloid / PET-tau imaging

Positron emission tomography with amyloid-targeting tracers — florbetapir, florbetaben and flutemetamol, all FDA-approved — allows in vivo visualisation of fibrillar amyloid-beta plaques, while second-generation tau PET tracers such as flortaucipir map neurofibrillary tangle burden and staging (Braak stages) in living patients. PET amyloid and tau status have become clinically actionable since 2023–2024, following the FDA approvals of lecanemab (Leqembi) and donanemab: both anti-amyloid antibody therapies require confirmed amyloid positivity for treatment eligibility, and tau PET staging increasingly informs prognosis and likely treatment benefit. Centiloid standardisation of amyloid PET allows cross-scanner and cross-tracer comparison, though reimbursement for diagnostic use remains limited in most healthcare systems. Radiation exposure (approximately 5–7 mSv per scan) and cost are relevant constraints for population screening applications.