FDG PET for Dementia and Neurodegenerative Diseases | CMS Coverage Update

Summary: The Centers for Medicare & Medicaid Services modified its coverage policy for FDG PET imaging in dementia and neurodegenerative diseases, effective May 15, 2026. Here's what billing teams need to do before that date.

CMS FDG PET dementia coverage policy has a long, complicated history — and this modification adds another chapter. The Centers for Medicare & Medicaid Services governs this coverage through its National Coverage Determination framework, and any change to these criteria directly affects neurology, nuclear medicine, and memory care practices that bill FDG PET studies. The policy does not list specific CPT or HCPCS codes in the data available for this update, but FDG PET imaging for dementia workup has historically tied to a small set of nuclear medicine procedure codes. Pull those from your current charge master and flag them now.

Quick-Reference Table

CMS FDG PET Dementia Coverage Criteria and Medical Necessity Requirements 2026

FDG PET imaging for dementia is not a routine Medicare benefit. It has always required specific medical necessity criteria to be met before CMS reimburses the claim. This modification signals that CMS is tightening, clarifying, or restructuring those criteria — and your documentation needs to reflect whatever the updated standard requires on the date of service.

The core principle hasn't changed: Medicare covers FDG PET for dementia evaluation only when it helps distinguish one specific diagnosis from another and when that distinction will change patient management. A scan ordered as a general cognitive workup or a confirmatory test after a clinical diagnosis is already established does not meet medical necessity under this coverage policy. That's always been true, and this modification likely reinforces it.

Prior authorization is not universally required for FDG PET under the Medicare fee-for-service program, but don't let that lull you into skipping the documentation step. Medicare Administrative Contractor reviews and post-payment audits hit FDG PET claims hard. Your documentation needs to show the specific differential diagnosis being evaluated, why clinical and other diagnostic tools were insufficient, and how the PET result will change management. If those three elements aren't in the chart note, the claim is vulnerable.

One more thing on prior authorization: if your patient has a Medicare Advantage plan, all bets are off. Medicare Advantage plans follow CMS coverage policy as a floor but can add prior authorization requirements on top. Check each plan's requirements separately before scheduling the scan.

CMS FDG PET Dementia Coverage History and Why This Modification Matters

Understanding what this modification changes requires knowing where CMS started. FDG PET for dementia workup has been a covered benefit under Medicare only under narrow conditions. Historically, CMS covered FDG PET when it was used to distinguish Alzheimer's disease from frontotemporal dementia — a clinically meaningful distinction because treatment and care planning differ significantly between those two diagnoses.

CMS has also covered FDG PET as part of Coverage with Evidence Development (CED) protocols, meaning the scan was covered only when performed within an approved clinical trial or registry. That requirement was a persistent source of claim denials for practices that didn't understand the CED framework. If you billed FDG PET outside a qualifying CED study during the periods when CED applied, those claims were non-covered by definition.

This 2026 modification may adjust the CED requirements, expand covered indications, revise the differential diagnosis criteria, or change the documentation standards. The effective date of May 15, 2026 is the line in the sand. Any FDG PET claim with a date of service on or after that date needs to meet the updated criteria. Claims dated before May 15, 2026 follow the prior version of the policy.

The real issue here is that changes to FDG PET dementia coverage policy have financial exposure that goes in both directions. If CMS expanded indications, you may now have coverage for patient populations you've been declining to scan or billing as non-covered. If CMS tightened criteria, claims you've been submitting may start denying at a higher rate.

CMS FDG PET Exclusions and Non-Covered Indications

CMS has historically excluded several uses of FDG PET from coverage in the dementia context, and this modification likely preserves those exclusions even if other criteria shift.

FDG PET is not covered as a screening tool in patients without documented cognitive symptoms. It's not covered to confirm a diagnosis that's already been established through clinical evaluation. And it's not covered when the differential diagnosis being evaluated doesn't have a management implication — meaning, if the result won't change what you do for the patient, CMS won't pay for the scan.

FDG PET for neurodegenerative diseases beyond Alzheimer's and frontotemporal dementia has historically been treated differently depending on the condition. Lewy body dementia, Parkinson's disease dementia, and other neurodegenerative presentations have had limited or no coverage under this specific NCD framework. Check the updated policy language carefully for any expansion or restriction of those indications.

Ordering providers also need documented evidence of prior workup. A clinical history and standard lab work aren't enough on their own. Structural imaging — typically MRI or CT — should be in the record before FDG PET is ordered. CMS expects FDG PET to be a later-stage diagnostic tool, not a first-line test.

Coverage Indications at a Glance

The policy data provided for this modification does not include a complete indication-by-indication breakdown. The table below reflects the established CMS framework for FDG PET dementia coverage as context for the May 15, 2026 modification. Confirm each row against the published policy update before using this table for billing decisions.

CMS FDG PET Billing Guidelines and Action Items 2026

CPT, HCPCS, and ICD-10 Codes for FDG PET Dementia Under This Policy

The policy data provided for this modification does not include a specific list of CPT, HCPCS, or ICD-10 codes. Do not use invented codes for billing purposes.

For FDG PET dementia billing, work with your nuclear medicine or radiology team to confirm the correct procedure codes currently in use at your facility. Map those codes to the updated coverage criteria once the full policy text is available. Cross-reference your ICD-10-CM diagnosis codes to ensure they accurately reflect the specific differential diagnosis being evaluated — vague dementia codes alone have historically been a trigger for claim denial on FDG PET claims.

If you have access to the PayerPolicy platform, use the policy detail page at app.payerpolicy.org/p/cms/288-v3. to pull the exact code list once it's published with the full policy update.