Positron Emission Tomography (NaF-18) to Identify Bone Metastasis of Cancer | CMS Coverage Update

Summary: The Centers for Medicare & Medicaid Services modified its coverage policy for Positron Emission Tomography using Sodium Fluoride-18 (NaF-18) to identify bone metastasis of cancer, with an effective date of May 15, 2026. Here's what billing teams need to know before that date.

CMS NaF-18 PET imaging for bone metastasis sits at an interesting crossroads — it's a technology that's been clinically available for years but has had a complicated reimbursement history under Medicare. This modification signals a shift in how the Centers for Medicare & Medicaid Services views this imaging modality. The policy does not list specific procedure codes in the available data, so your billing team needs to review the full policy document at app.payerpolicy.org/p/cms/336-v2. and confirm code applicability with your Medicare Administrative Contractor before billing.

Quick-Reference Table

CMS NaF-18 PET Bone Metastasis Coverage Criteria and Medical Necessity Requirements 2026

The CMS coverage policy for NaF-18 PET imaging has always tied reimbursement tightly to medical necessity — and that hasn't changed. What the May 15, 2026 modification likely adjusts is where the lines are drawn on which cancer types, clinical scenarios, or ordering contexts qualify.

NaF-18 PET scans for bone metastasis staging are not universally covered under Medicare. Coverage has historically been tied to specific cancer types and to scenarios where conventional imaging (standard bone scans using Tc-99m) was insufficient or inconclusive. If your practice orders NaF-18 PET as a first-line bone imaging tool without documented clinical rationale, you're looking at a claim denial.

Medical necessity documentation is the core of this coverage policy. Your physicians need to clearly document why NaF-18 PET was ordered over alternatives — including what prior imaging showed, what clinical decision this scan will drive, and how the results affect the patient's cancer management plan. Vague documentation like "evaluate for bone mets" won't hold up under a Medicare audit.

Prior authorization requirements under this policy depend on your specific MAC jurisdiction. Some MACs have required prior auth for NaF-18 PET; others have not. The May 2026 modification may standardize or shift those requirements. Confirm with your MAC what the process looks like after the effective date — don't assume your current workflow still applies.

The real issue here is that NaF-18 PET and conventional technetium-based bone scans are clinically similar enough that Medicare reviewers will ask why the more expensive PET option was chosen. Your physicians need to answer that question in the chart before the claim ever hits the payer.

CMS NaF-18 PET Exclusions and Non-Covered Indications

Not every oncology patient with suspected bone involvement qualifies for a covered NaF-18 PET scan under Medicare. Coverage has historically been withheld in certain scenarios, and the May 2026 modification does not signal a blanket expansion.

Screening without known cancer is not covered. NaF-18 PET for bone metastasis is a staging and restaging tool, not a screening tool. Using it on patients without an established cancer diagnosis will result in a denied claim.

Routine surveillance in patients with no new signs or symptoms of progression has been a gray area — and a common source of denials. Medicare expects clinical change or a specific management question to justify the scan. Document what changed clinically. Document what decision this scan will inform. Without that, you're billing against the coverage policy.

Duplicate imaging is another denial trigger. If a patient already had a Tc-99m bone scan that gave adequate diagnostic information, ordering NaF-18 PET on top of it without clear documented rationale puts your claim at risk. The chart needs to explain the gap.

Some MAC-level local coverage determinations may be more restrictive than the national coverage policy. Always check your specific MAC's LCD alongside the national policy — the more restrictive of the two governs your billing.

Coverage Indications at a Glance

The policy document does not list specific indication-level coverage criteria in the available data. The table below reflects the general framework that CMS has historically applied to NaF-18 PET for bone metastasis. Confirm each indication against the full policy document and your MAC's LCD before billing after May 15, 2026.

CMS NaF-18 PET Billing Guidelines and Action Items 2026

This is where the modification directly hits your revenue cycle. The steps below are based on what typically shifts in a CMS NaF-18 PET policy modification and what your billing team should lock down before May 15, 2026.

CPT, HCPCS, and ICD-10 Codes for NaF-18 PET Bone Metastasis Imaging

The policy data provided for this modification does not include specific CPT, HCPCS, or ICD-10 codes. This is not unusual for a CMS national coverage determination modification — the codes are often referenced in the policy body or in associated billing instructions rather than listed separately.

Do not assume standard PET imaging codes apply without verification. NaF-18 PET uses a different radiopharmaceutical than FDG-PET, and the applicable billing codes may differ. Using incorrect codes creates claim denials and potential overpayment liability.

How to Get the Right Codes

Go to the full policy at the CMS source (linked in the policy data above). Look for the coverage determinations section, which typically references applicable HCPCS codes for the radiopharmaceutical and the associated PET procedure codes. Cross-reference with your MAC's LCD if one exists for your jurisdiction.

Ask your MAC's Provider Outreach and Education team directly if you can't find clear guidance in the policy document. They're required to help with this — use them.

Once you confirm the applicable codes, update your charge description master (CDM) before May 15, 2026. Don't wait until a claim denies to find out you were billing the wrong code.