Tauklarify, a new PET imaging agent approved by the FDA in August 2026, detects tau tangles in the brain, while amyloid PET detects amyloid plaques — the other hallmark protein of Alzheimer's disease. For someone with mild cognitive impairment (MCI), the practical difference is this: amyloid PET tells you whether Alzheimer's pathology is present at all, while tau PET tells you how far it has progressed, because tau burden tracks more closely with symptom severity. Tauklarify (florquinitau F 18 injection, formerly known as MK-6240) comes from Lantheus and Enigma Biomedical and was cleared by the FDA on August 14, 2026, specifically for imaging tau neurofibrillary tangles in adults being evaluated for Alzheimer's disease, including those with MCI, according to Lantheus's announcement reported by Healio. It is the second tau PET tracer on the market, joining Eli Lilly's Tauvid, and gives clinicians and patients a real choice to weigh against the amyloid scans that have been standard for over a decade.
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 CMS — 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 Each Scan Actually Measures
- How Reliable Is a Tauklarify Scan?
- What Tauklarify Cannot Tell You
- The Logistics — What the Scan Day Looks Like
- Coverage and Cost — What to Ask Before Scheduling
- Deciding Between the Two With a Clinician
- Frequently Asked Questions
What Each Scan Actually Measures
Amyloid PET uses tracers such as Amyvid, Vizamyl, and Neuraceq to visualize amyloid plaques, one of the two defining proteins in Alzheimer's disease. Amyloid can turn up on a scan years before any symptoms appear, and the amount detected does not reliably track with how impaired a person's thinking has become, according to AuntMinnie's coverage of the Tauklarify approval. Tau PET, using Tauklarify or Tauvid, visualizes neurofibrillary tangles — twisted fibers that build up inside brain cells as Alzheimer's progresses. Tangle burden correlates more closely with a person's actual cognitive stage and symptoms than amyloid does, per the same report.
For someone already diagnosed with MCI, that distinction matters: amyloid PET answers whether Alzheimer's pathology is present, while tau PET gives a clearer picture of how advanced the disease process already is. Neither scan is a stand-alone diagnosis. Tauklarify's own FDA label states it is indicated for detecting tau pathology in adults with cognitive impairment, including MCI, but it does not diagnose Alzheimer's disease by itself, according to Psychiatric Times. Both scans are meant to be interpreted alongside a clinical evaluation, not in place of one.
How Reliable Is a Tauklarify Scan?
The FDA approval rested on two blinded-read studies covering 617 participants, split between people with MCI, people with mild Alzheimer's dementia, and cognitively unimpaired volunteers. Five independent readers per study classified each scan against a reference standard built from cognitive status plus amyloid PET results, according to NeurologyLive's summary of August 2026 FDA actions. In the larger of the two studies, which included 338 subjects, readers agreed with the reference standard on tau-positive scans 68% to 82% of the time (positive percent agreement), and agreed on tau-negative scans 93% to 99% of the time (negative percent agreement).
A second study found positive percent agreement of 80% to 88%, per Healio's report on the approval. In plain terms, Tauklarify is more consistent at correctly identifying a tau-negative scan than at catching every tau-positive case. A negative result is on firmer ground than a borderline positive one, so a scan that comes back positive but the clinical picture doesn't fit may be worth a second look rather than treated as definitive.
What Tauklarify Cannot Tell You
Tauklarify's label is explicit that it has not been established as safe or effective for evaluating tau buildup outside of Alzheimer's disease. It should not be used to assess suspected frontotemporal dementia or other non-Alzheimer's tauopathies, according to PharmaShots. If a person's MCI symptoms raise suspicion of a different underlying disease, Tauklarify is not the tool to sort that out.
This matters because MCI has more than one possible cause. A tau PET scan only answers the Alzheimer's-specific question; it says nothing useful about other neurodegenerative conditions that can also impair cognition. Anyone whose clinician suspects something other than Alzheimer's should ask directly whether tau PET is even the right test before scheduling one.
The Logistics — What the Scan Day Looks Like
Both amyloid and tau PET scans follow a similar routine. Tauklarify is given as a single intravenous injection, followed by about a 90-minute wait, then a PET scan lasting roughly 20 minutes — comparable timing to existing amyloid tracers and to Tauvid, the other approved tau tracer, according to Fierce Biotech's report via Drugs.com. There's no meaningful difference in time commitment or invasiveness between an amyloid scan and a tau scan — the choice comes down to what question the clinician needs answered, not which test is easier to sit through.
Coverage and Cost — What to Ask Before Scheduling
Amyloid PET coverage already varies by region. In 2023, the Centers for Medicare & Medicaid Services (CMS) removed its national coverage determination for amyloid PET, eliminating the old one-scan-per-lifetime limit but also handing coverage decisions to local Medicare Administrative Contractors (MACs) instead of a single national rule, according to Radiology Business's report on the CMS decision. That means two people in different states can get different coverage answers for the same scan.
Tauklarify is newer still: as of its approval, there is no Medicare national coverage determination specific to it. Coverage is expected to follow the same local-MAC pathway already used for Tauvid rather than arrive through an immediate national ruling, per CMS's amyloid PET coverage page. Before scheduling either scan, it's worth confirming directly with the imaging center and insurer:.
- Whether the local Medicare contractor has published a coverage policy for Tauklarify specifically
- Whether a referring clinician's diagnosis and documentation meet that contractor's criteria
- What out-of-pocket cost applies if coverage is denied or if private insurance follows a different policy than Medicare
Deciding Between the Two With a Clinician
For a person with MCI, the two scans answer different questions, and clinicians can order either or both. Amyloid PET establishes whether Alzheimer's-related plaque pathology is present at all.
Tau PET, now available through either Tauklarify or Tauvid, estimates how much tangle pathology has built up — a measure tied more closely to current symptom severity and likely prognosis, according to PatientWorthy's coverage of the approval. A practical starting point is to ask the ordering clinician which question is actually open: if the issue is whether Alzheimer's pathology exists at all, amyloid PET is the direct answer; if Alzheimer's has already been established and the question is how advanced the tangle burden is, tau PET with Tauklarify adds information amyloid PET cannot. Because Tauklarify's validated use stops at Alzheimer's evaluation, any suspicion of a different diagnosis should be resolved before ordering it, not after.
Frequently Asked Questions
Can someone get both an amyloid PET scan and a Tauklarify tau PET scan?
Yes — the two tracers measure different proteins, and clinicians can order both when a fuller picture of Alzheimer's pathology and tangle burden is needed, per PatientWorthy.
Is Tauklarify a treatment for Alzheimer's disease?
No. It is a diagnostic imaging agent used to visualize tau pathology; it does not treat the disease, according to Psychiatric Times.
Does a negative Tauklarify scan rule out Alzheimer's disease?
A negative result showed 93%-99% agreement with the reference standard in the approval studies, making it fairly reliable, though the scan is meant to be interpreted alongside clinical evaluation, not alone, per Healio.
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