If you need regular MRI, CT or PET scans, for example to monitor cancer, a heart condition or a chronic illness, your Medicare choice affects what you pay and how easily you get each scan. Neither option is best for everyone. This guide compares how Original Medicare and Medicare Advantage handle frequent imaging, so you can ask the right questions before you choose.
Key takeaways
- Both options cover medically necessary imaging. The differences are in cost sharing, networks and prior authorization.
- Original Medicare has no yearly out-of-pocket limit on its own. Many people add a Medigap policy to cover most of the 20% coinsurance.
- Medicare Advantage plans must cap your yearly in-network costs. In 2026, the federal maximum is $9,250, and many plans set lower limits.
- Medicare Advantage plans often require prior authorization for imaging and may limit you to network providers.
- Switching from Medicare Advantage back to Original Medicare with Medigap later can be hard in many states. Think about this before you decide.
Side-by-side comparison
| Original Medicare (+ optional Medigap) | Medicare Advantage | |
|---|---|---|
| Imaging coverage | Medically necessary scans under Part B | Same coverage, sometimes with extra rules |
| What you pay per scan | 20% after the Part B deductible ($283 in 2026), or a hospital copay; Medigap can cover most of it | Plan sets a copay or coinsurance per scan |
| Yearly out-of-pocket limit | None without Medigap | Required: up to $9,250 in network in 2026 |
| Choice of provider | Any provider that accepts Medicare | Usually a network; out-of-network costs more or isn’t covered |
| Prior authorization | Rarely required for imaging | Often required for MRI, CT and PET |
| Monthly cost | Part B premium ($202.90 in 2026), plus a Medigap premium if you buy one | Part B premium, plus the plan’s premium (often $0) |
| Changes from year to year | Rules set by Medicare | Plans can change copays and networks each year |
How Original Medicare handles frequent scans
With Original Medicare, you pay the Part B deductible once a year, then usually 20% of the Medicare-approved amount for each scan at a doctor’s office or independent imaging center. At a hospital outpatient department, you pay a copay that can be higher, though in most cases it’s capped at the Part A deductible ($1,736 in 2026) per service.
The catch for frequent scans is that 20% has no ceiling. Several PET/CT or MRI scans a year can add up.
That’s why many people with ongoing conditions buy a Medigap (Medicare Supplement) policy. Depending on the plan, Medigap covers most or all of your Part B coinsurance and hospital copays. You pay a monthly premium for it, which varies by plan, age and state.
What people like about it: you can use any provider in the country that accepts Medicare, including major cancer centers, and you rarely need prior authorization for imaging.
How Medicare Advantage handles frequent scans
Medicare Advantage plans are run by private insurers approved by Medicare. They must cover everything Original Medicare does, but they set their own cost sharing, often a fixed copay per MRI, CT or PET scan.
The out-of-pocket limit. Every Medicare Advantage plan must cap what you pay for covered in-network services each year. According to KFF, the federal maximum in 2026 is $9,250 in network and $13,900 combined for plans that cover out-of-network care. The average plan sets a lower in-network limit, about $5,400.
Prior authorization. Medicare Advantage plans often require approval before advanced imaging. KFF found that Medicare Advantage insurers received about 53 million prior authorization requests in 2024 and denied 7.7% in full or in part. Only about 1 in 9 denials was appealed, but about 81% of the appeals succeeded, fully or partly.
Networks. HMO plans usually cover only in-network providers except in emergencies. PPO plans cover out-of-network care at a higher cost. If you’re treated at a specific hospital or cancer center, check that it’s in the plan’s network for imaging.
What people like about it: low or $0 premiums in many areas, a yearly cap on costs and extra benefits like dental or vision in many plans.
A worked example
The numbers below are hypothetical, to show how the math works. Your plan’s costs and the Medicare-approved amounts will be different.
Say you need four PET/CT scans a year, and the Medicare-approved amount is $1,500 per scan.
| Option | How it works | Your yearly cost for the scans |
|---|---|---|
| Original Medicare only | $283 deductible + 20% of the remaining $5,717 | About $1,426, plus the radiologist’s fees, with no cap |
| Original Medicare + Medigap that covers coinsurance but not the Part B deductible | You pay the $283 deductible | About $283, plus the Medigap premium |
| Medicare Advantage with a $250 copay per PET scan | 4 × $250 | About $1,000, up to the plan’s yearly limit, plus any plan premium |
The right answer depends on your premiums, your plan’s copays, how many scans and other services you need, and where you want to be treated.
The switching question
This matters a lot if your health needs might grow.
- When you first get Medicare Part B at 65 or older, you have a 6-month Medigap open enrollment period. During it, insurers must sell you a Medigap policy without considering your health.
- If you join a Medicare Advantage plan when you’re first eligible and leave it within the first 12 months, you generally have a trial right to buy Medigap without medical underwriting.
- After those windows, in most states, Medigap insurers can refuse to sell you a policy or charge more because of your health. A few states have broader protections.
In other words, choosing Medicare Advantage first and switching back later isn’t always possible on the same terms.
Questions to ask before you choose
- Are my imaging center, my hospital and my specialists in the plan’s network?
- What is the copay or coinsurance for MRI, CT and PET in this plan?
- Do these scans need prior authorization, and how long does it usually take?
- What is the plan’s in-network out-of-pocket limit for next year?
- If I choose Original Medicare, which Medigap plans are available to me, and what do they cost?
- If I choose Medicare Advantage now, could I buy Medigap later in my state?
For free, unbiased advice, contact your State Health Insurance Assistance Program (SHIP). You can also compare plans in the Medicare Plan Finder on Medicare.gov.
Frequently asked questions
Does Medicare Advantage cover PET scans for cancer? Yes, when they’re medically necessary, but usually with prior authorization and network rules.
Is there an out-of-pocket maximum in Original Medicare? No. Original Medicare on its own has no yearly limit. A Medigap policy can cover much of your cost sharing.
When can I switch? During Medicare Open Enrollment, October 15 to December 7, for coverage starting January 1. If you’re in a Medicare Advantage plan, you can also switch plans or return to Original Medicare from January 1 to March 31.
Can my Medicare Advantage plan change my imaging copay? Yes, plans can change costs and networks every year. Read the Annual Notice of Change your plan sends each fall.
Sources
- KFF: Medicare Advantage Out-of-Pocket Limits: Variation and Trends (May 2026).
- KFF: Medicare Advantage Insurers Made Nearly 53 Million Prior Authorization Determinations in 2024 (January 2026).
- Medicare.gov: Diagnostic non-laboratory tests; Outpatient hospital services.
- Centers for Medicare & Medicaid Services (CMS): 2026 Medicare Parts A & B premiums and deductibles.
- Medicare Rights Center (Medicare Interactive): Maximum out-of-pocket limit.
This article is for general information only and isn’t financial or insurance advice. It doesn’t recommend a specific plan. For help with your situation, contact your SHIP or 1-800-MEDICARE.