No, Medicare does not cover an FDG-PET scan for a routine Alzheimer's evaluation alone. It covers FDG-PET brain imaging for dementia only for the differential diagnosis of frontotemporal dementia versus Alzheimer's disease, or in a CMS-approved clinical trial. An FDG-PET brain scan measures how brain cells use glucose, which shows patterns of reduced activity. That pattern can help distinguish Alzheimer's disease from frontotemporal dementia when both remain plausible after a full workup.
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:
- Explore the official data from CMS — Use this primary source to review the underlying data.
- Read the official guidance from CMS — Use this primary source to verify the official guidance.
Table of Contents
- When does Medicare cover the scan?
- What evaluation must come first?
- What if you have mild impairment or early dementia?
- What should families bring and ask?
When does Medicare cover the scan?
Coverage applies to a narrow group. According to the Centers for Medicare & Medicaid Services, the patient has a recent dementia diagnosis, at least six months of documented cognitive decline, and meets diagnostic criteria for both Alzheimer's and frontotemporal dementia, described in the CMS coverage decision. The Alzheimer's Association gives the same description: recent dementia with at least six months of documented decline, when criteria for both conditions are met.
A routine memory evaluation does not qualify unless frontotemporal dementia is genuinely in play. Amyloid PET is different. It looks for Alzheimer's amyloid plaques, while FDG-PET looks at brain metabolism, and Medicare treats them under separate rules.
What evaluation must come first?
Coverage requires an evaluation by a physician experienced in dementia. That visit includes history from the patient and an informant, physical and neurologic examination, cognitive testing, laboratory work, and assessment for other causes. The cause must still be uncertain after that workup.
The record should address diagnostic criteria, at least one year of progressive illness, prior CT or MRI, and workup for encephalopathy where applicable. Ask the clinic to document each element. Medicare decisions turn on the written record, not on symptoms alone.
What if you have mild impairment or early dementia?
For mild cognitive impairment or early dementia outside the Alzheimer's-versus-frontotemporal-dementia question, FDG-PET is covered only inside a CMS-approved practical trial. According to the Centers for Medicare & Medicaid Services, those trials include patient safeguards and structured data collection, listed on the CMS trial registry page. This is a clinical-use gap.
According to the American College of Radiology, FDG-PET brain imaging is "Usually Appropriate" for mild cognitive impairment and suspected Alzheimer presentations in its 2024 dementia guidance, explained in the ACR dementia imaging guidance. So a doctor may recommend the scan as good medicine even when Medicare will not pay outside the covered diagnosis or a trial. Ask whether a qualifying trial is open near you before scheduling.
What should families bring and ask?
Expect a dementia-specialist referral, proof of six months of decline, prior exam notes, cognitive test scores, labs, and brain images. The imaging facility and ordering physician also need coverage documentation showing the frontotemporal-dementia alternative. Use this checklist at the appointment: If the cause is still unclear but both diagnoses fit, ask the specialist to state that uncertainty and the competing diagnoses in the referral order.
- Ask whether you meet criteria for both Alzheimer's and frontotemporal dementia.
- Bring dated examples of decline, test results, medication lists, and prior CT or MRI reports.
- Ask for the exact diagnosis codes, coverage statement, and trial options if you do not qualify.
