To get a PET scan covered by insurance, you need three things lined up before the scan happens: documented medical necessity from your ordering physician, prior authorization from your insurer, and an in-network facility that will bill using the correct code. Most PET scans ordered for established indications like cancer staging or treatment response do get approved when the paperwork is handled correctly. Skip any of these steps and you’re looking at a denial or a bill that can run into the thousands.
Confirm Your Plan Covers the Scan
Start before your doctor even sends the order. Pull up your summary of benefits or call the number on the back of your insurance card, and ask three specific questions. Does the plan classify PET scans as advanced imaging that requires preapproval? Which diagnoses does the plan consider eligible? And does coverage depend on the type of facility you use?
Most plans cover PET scans for cancer staging, evaluating treatment response, and certain cardiac or neurological conditions. Some limit coverage to diagnoses spelled out in the plan’s medical policy, which you can usually find on the insurer’s website by searching “PET scan medical policy.”
Watch for frequency limits. Some plans approve only one PET scan per year for a given diagnosis unless your physician provides additional justification. Others cover initial staging but not routine surveillance. Ask specifically whether your plan treats hospital outpatient departments differently from freestanding imaging centers, because some insurers apply higher coinsurance at hospital-based facilities.
Get Prior Authorization Approved
Prior authorization is the make-or-break step. Most insurers require it before they’ll pay, and skipping it almost guarantees a denial. Your ordering physician submits the request along with clinical notes, relevant test results, pathology reports, and a clear explanation of why the scan is needed.1UHCprovider.com. Outpatient Radiology Prior Authorization Program – Frequently Asked Questions Insurers evaluate the request against evidence-based clinical guidelines, often drawn from the National Comprehensive Cancer Network or the American College of Radiology.
Turnaround depends on the type of plan and the urgency. Under federal rules governing employer-sponsored plans, insurers must respond to non-urgent pre-service requests within 15 days, with a possible 15-day extension if they need more information. Urgent requests require a decision within 72 hours.2eCFR. 29 CFR 2560.503-1 – Claims Procedure A newer CMS rule tightens these windows for Medicare Advantage and Medicaid managed care plans, requiring standard decisions within seven calendar days and expedited decisions within 72 hours.3Centers for Medicare & Medicaid Services. CMS Interoperability and Prior Authorization Final Rule CMS-0057-F
When approved, the insurer issues an authorization number that must be provided to the imaging facility. Authorizations expire. One major insurer gives only 45 days to complete the scan before the authorization lapses.1UHCprovider.com. Outpatient Radiology Prior Authorization Program – Frequently Asked Questions If your scan is delayed past that date, your doctor has to request a new authorization.
If the Request Is Denied, Ask for a Peer-to-Peer Review
A denied prior authorization doesn’t have to end the process. Your doctor can request a peer-to-peer review, a phone conversation between your treating physician and the insurance company’s medical director. Many denials get reversed at this stage because your doctor can walk through the clinical reasoning in a way that paperwork alone doesn’t convey. The reviewing physician is supposed to have relevant clinical expertise, and the determination should come within 24 hours of the call. Try this before filing a formal written appeal. It’s faster and less adversarial.
Use an In-Network Facility and Confirm the Billing Code
Even with prior authorization in hand, where you get the scan affects both coverage and cost. Using an out-of-network facility can result in a flat denial or dramatically higher cost-sharing. Check your insurer’s provider directory or call to confirm which imaging centers are in-network for PET scans specifically, since some facilities may be in-network for basic imaging but not for nuclear medicine.
If you have a choice between a hospital outpatient department and a freestanding imaging center, the freestanding center will almost always cost less. Hospital outpatient departments charge a facility fee that independent centers don’t, and that fee gets baked into your coinsurance. Some insurers reduce coinsurance at freestanding centers to steer members toward them.
Ask the imaging facility what CPT code they’ll use. PET/CT scans use different codes depending on the extent of the scan: 78815 for skull base to mid-thigh, 78816 for whole body (vertex to feet), and 78814 for a limited area. You don’t need to memorize these, but confirm the code matches both what your doctor ordered and what the prior authorization specifies. A mismatch between the authorized code and the billed code is one of the most common reasons for post-scan claim rejections.
The Radiologist Can’t Balance-Bill You
Even at an in-network facility, the radiologist who reads your scan might be out-of-network. The No Surprises Act now prohibits balance billing in this situation. Radiology is classified as an ancillary service, and out-of-network providers of ancillary services at in-network facilities cannot balance-bill you under any circumstances. Your cost-sharing is capped at whatever your plan’s in-network rate would be.4Centers for Medicare & Medicaid Services. No Surprises Act Overview of Key Consumer Protections Unlike some other No Surprises Act protections, this one has no notice-and-consent exception. Providers cannot ask you to waive it.5Centers for Medicare & Medicaid Services. The No Surprises Act’s Prohibitions on Balance Billing
Medicare and Medicaid Coverage
Original Medicare (Part B) covers PET scans deemed medically necessary at Medicare-approved facilities. For oncology, CMS nationally covers one FDG-PET scan for patients with cancers that are biopsy-proven or strongly suspected, when the scan is needed to determine initial treatment strategy. Covered cancers include breast, cervical, colorectal, esophageal, head and neck, lymphoma, melanoma, non-small cell lung, ovarian, thyroid, and myeloma.6Centers for Medicare & Medicaid Services. Positron Emission Tomography (FDG) for Oncologic Conditions PET scans for other cancers or for subsequent treatment monitoring may require coverage through CMS’s evidence development program, which means the scan must be performed as part of an approved clinical study.
Under Original Medicare, you pay the Part B deductible ($283 in 2026), then 20% coinsurance on the Medicare-approved amount. A Medigap plan may cover part or all of that coinsurance. Medicare Advantage plans provide at least the same coverage as Original Medicare, but they can require prior authorization and may require a referral from your primary care physician.
Medicaid coverage varies by state. Federal law requires states to cover laboratory and X-ray services, but PET scans fall under the broader category of “diagnostic, screening, preventive, and rehabilitative services,” which states can choose to include or exclude.7Medicaid.gov. Mandatory and Optional Medicaid Benefits Most state Medicaid programs do cover PET scans for approved indications, but prior authorization requirements and eligible diagnoses differ from state to state. Contact your state Medicaid agency or managed care plan to confirm before scheduling.
Appealing a Denied Claim
When a claim is denied after the scan has already been performed, read the explanation of benefits or denial letter carefully. Insurers are required to tell you why they denied the claim and how to dispute the decision.8HealthCare.gov. How to Appeal an Insurance Company Decision Your strategy depends on the reason.
Coding or Administrative Errors
A surprising number of denials trace to billing mistakes rather than actual coverage disputes. A mismatched CPT code, a missing authorization number, or a transposed digit in your member ID can trigger an automatic denial. If the denial letter references a lack of prior authorization and you actually obtained one, contact the imaging facility’s billing department. They can often resolve the issue by resubmitting with corrected information. No formal appeal needed.
Medical Necessity Denials
If the insurer says the scan wasn’t medically necessary, your ordering physician needs to write a letter explaining why the scan was clinically appropriate. Attach medical records, pathology reports, prior imaging results, and clinical guidelines (NCCN, for example) that support PET imaging for your specific condition. That documentation package is the backbone of your internal appeal.
Experimental or Investigational Denials
This category is harder. Insurers sometimes deny PET scans that use newer radiotracers or target less-established indications by labeling them experimental. PET scans for certain types of dementia, for instance, have been denied on the grounds that standard clinical evaluation is sufficient in most cases. Denials in this category have been overturned when the scan served a specific diagnostic purpose that other tests couldn’t accomplish, such as distinguishing Alzheimer’s disease from frontotemporal dementia when neuropsychological testing was inconclusive. Published studies supporting the specific tracer or indication strengthen your appeal considerably.
Your Appeal Rights and Deadlines
Federal law gives you a two-stage appeal process that applies to all non-grandfathered health plans.
Internal Appeal
You have the right to ask your insurer to conduct a full and fair review of any denied claim. For pre-service denials such as a rejected prior authorization, the insurer must decide within 15 days under ERISA rules, with a possible 15-day extension.2eCFR. 29 CFR 2560.503-1 – Claims Procedure Post-service claims (the scan already happened) get a 30-day decision window with a similar extension. Urgent cases require a response within 72 hours. If your insurer misses these deadlines, that itself can be grounds for overturning the denial.
External Review
If the internal appeal fails, you can escalate to an external review, where an independent third party evaluates the case. Under the Affordable Care Act, every state must have an external review process that meets federal consumer protection standards.9HealthCare.gov. External Review You have four months from the date of the final internal denial to file a written request. The external reviewer’s decision is binding on the insurer.10Centers for Medicare & Medicaid Services. External Appeals
External review is where persistence tends to pay off. Independent reviewers look at the medical evidence without the insurer’s institutional bias toward denial, and strong clinical documentation from your treating physician carries real weight. Your state’s department of insurance can walk you through the filing steps and timelines that apply in your jurisdiction.