Flortaucipir F-18

Flortaucipir F-18 (Tauvid, Eli Lilly, developed by Avid Radiopharmaceuticals) was approved by the FDA on 28 May 2020, the first tau PET tracer to reach the US market. It is indicated for PET imaging of the brain to estimate the density and distribution of aggregated tau neurofibrillary tangles in adult patients with cognitive impairment being evaluated for AD; the label explicitly states Tauvid is not indicated for evaluating chronic traumatic encephalopathy, since tau conformation and distribution differ in that condition. The EMA-approved indication (Tauvid EPAR) is PET imaging to assess the neocortical distribution of aggregated tau neurofibrillary tangles.

The recommended dose is 370 MBq (10 mCi) as an intravenous bolus in up to 10 mL, with a 20-minute PET image acquired starting about 80 minutes post-injection; the maximum mass dose is 20 micrograms and effective dose from 370 MBq is about 8.7 mSv. A positive scan (Braak-stage-like scoring, described in the label as 'B3' tau pathology, meaning widely distributed neocortical uptake in posterolateral temporal, occipital or parietal/precuneus regions with or without frontal involvement) supports a diagnosis of AD only in conjunction with clinical and other diagnostic evaluation; the EMA label also notes variable specificity and the possibility of false positives.

In the 2024 Alzheimer's Association revised diagnostic criteria, tau PET is treated as a 'Core 2' biomarker used to stage AD severity once amyloid positivity (Core 1) has established the diagnosis, rather than as a stand-alone diagnostic test. The 2025 SNMMI/Alzheimer's Association appropriate use criteria rate tau PET as 'appropriate' (score 8) alongside amyloid PET for determining eligibility for an approved amyloid-targeting therapy, though the workgroup notes that tau PET for treatment eligibility is not itself required in the FDA prescribing information for lecanemab or donanemab. There is no dedicated Medicare national coverage determination for tau PET; it falls under the same PET framework applied by CMS and local Medicare Administrative Contractors as other diagnostic radiopharmaceuticals.