The FDA approved Tauklarify (florquinitau F-18, also known as MK-6240) on August 14, 2026, a new tau PET imaging agent from Lantheus. It gives doctors a second FDA-approved way to see tau tangles in the brain, distinct from amyloid PET, and it matters most for people already diagnosed with mild cognitive impairment (MCI) — a stage between normal aging and dementia where thinking or memory problems are noticeable but daily function is largely intact. For someone with MCI, the practical question is not which scan is "better" but which question each scan answers. Tauklarify and amyloid PET look for different proteins tied to Alzheimer's disease, and new clinical guidance now says both have the clearest value at exactly this stage of cognitive change, according to the Alzheimer's Association and SNMMI's updated appropriate use criteria.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Official resources:
- Read the official notice from Lantheus — Use this primary source to verify the official announcement.
- Read the official notice from Healio — Use this primary source to verify the official announcement.
Table of Contents
- What Tauklarify actually is
- Tau PET vs. amyloid PET — what each one is actually looking for
- Why MCI is the stage these scans are meant for
- What this means for access, cost, and timing right now
- Frequently Asked Questions
What Tauklarify actually is
Tauklarify is Lantheus' brand name for florquinitau F-18, a radioactive tracer injected before a PET brain scan. It is approved for adults with cognitive impairment being evaluated for Alzheimer's disease, specifically to detect tau neurofibrillary tangles — twisted protein fibers inside neurons that build up as Alzheimer's progresses. The FDA has not established that it works for other tau-related brain diseases, so its approved use is limited to Alzheimer's workups, according to coverage of the FDA approval. It is the second tau PET agent ever approved in the US, following Eli Lilly's Tauvid (flortaucipir F-18) in 2020, according to Lantheus' approval announcement.
Lantheus obtained the rights to this compound from Enigma Biomedical USA in 2023, then carried it through FDA review under a fast-track designation, with the agency accepting the application in October 2025 and acting by its August 13, 2026 target date, according to NeurologyLive. The approval rests on two blinded-read studies covering more than 500 people combined (279 in one, 338 in the other). Readers agreed with each other at a high rate, and the scans' positive findings matched independent reference assessments roughly 68% to 88% of the time across the two studies, according to PharmaShots' review of the FDA data. Safety data from 1,734 patients showed adverse reactions — mainly headache and injection-site irritation — in fewer than 1% of cases, a tolerability profile in line with other PET tracers, according to coverage in Applied Radiology.
Tau PET vs. amyloid PET — what each one is actually looking for
Amyloid PET and tau PET scan for two different proteins, and they are not interchangeable tools. Amyloid PET detects amyloid plaques, the sticky clumps that build up between brain cells and are one of the two defining features of Alzheimer's disease. Tau PET agents like Tauklarify instead visualize neurofibrillary tangles, the twisted tau protein strands that accumulate inside neurons.
The distinction matters because the two proteins behave differently over the course of the disease. Amyloid PET is good at confirming or ruling out Alzheimer's pathology, but tau burden tracks more closely with how severe a person's cognitive symptoms actually are, according to NeurologyLive. In practice, that means amyloid PET answers "is Alzheimer's pathology present at all," while tau PET helps answer "how far has it progressed." Because the two scans answer different questions, specialists increasingly order them as complementary pieces of the same workup rather than substitutes for each other. A person can have a positive amyloid scan years before tau pathology is extensive enough to explain their symptoms, which is part of why clinical guidance now treats mild cognitive impairment as the stage where both scans carry the most diagnostic weight.
Why MCI is the stage these scans are meant for
The updated Appropriate Use Criteria, jointly issued by the Alzheimer's Association and SNMMI, mark the first revision since the original 2013 amyloid-only criteria. Their strongest, most favorable recommendation is for using amyloid and tau PET to assess and estimate prognosis specifically in people who already have mild cognitive impairment, according to the Alzheimer's Association. The same criteria also strongly support these scans for dementia whose cause is unclear, and for deciding whether someone qualifies for — and is responding to — newer disease-modifying Alzheimer's treatments, according to RadiologyBusiness' coverage of the update.
That last use is becoming more relevant as more anti-amyloid drugs reach the market and require confirmed pathology before treatment starts. The criteria are just as explicit about where these scans do not belong. They advise against scanning people with normal cognition, even those who carry the APOE4 gene variant linked to higher Alzheimer's risk, and against ordering a scan for nonmedical reasons such as legal proceedings or insurance determinations. A scan ordered outside these criteria is unlikely to change a person's care and isn't what the guidance is built around.
What this means for access, cost, and timing right now
Approval is not the same as availability. Shortly after clearing the FDA, Lantheus said it was still working out "the most appropriate path toward broader commercial availability" for Tauklarify, without naming a date or list of imaging centers, according to coverage of the Lantheus announcement.
For patients, that means a few things stay unsettled in the near term: A person with MCI who wants to know if tau PET is relevant to their case should start the conversation with the specialist managing their cognitive evaluation — typically a neurologist or memory-disorder clinic — rather than requesting the scan directly. That clinician can determine whether the person's situation matches the Appropriate Use Criteria's MCI-assessment recommendation, and can track whether Tauklarify has become available at a facility they can reach, given that Lantheus had not finalized its rollout plan as of the approval announcement.
- Which imaging centers and hospitals will stock and administer the tracer
- Whether and how insurance, including Medicare, will cover the scan
- How a Tauklarify scan would be scheduled relative to other parts of an MCI workup, such as an amyloid PET scan or cognitive testing
Frequently Asked Questions
Is Tauklarify the same thing as an amyloid PET scan?
No. Amyloid PET looks for amyloid plaques, while Tauklarify is a tau PET tracer that visualizes neurofibrillary tangles — a different protein that tracks more closely with symptom severity.
Can someone with no cognitive symptoms request a Tauklarify scan to check their Alzheimer's risk?
The updated Appropriate Use Criteria specifically advise against scanning cognitively unimpaired people, including those who carry the APOE4 gene variant.
Is Tauklarify the first tau PET tracer approved in the US?
No. It is the second, following Eli Lilly's Tauvid (flortaucipir F-18), which the FDA approved in 2020.
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