How to appeal an MRI, CT or PET scan denial

Some health plans hand imaging review to an outside company. Premera Blue Cross, for example, says an outside company manages prior authorization for advanced imaging for its plan, covering CT, MRI, MRA and PET scans among others. Another plan’s provider manual tells doctors to contact the vendor that issued the denial to discuss it.

That means the name on your denial letter may be a company you have never heard of. Follow the appeal instructions in the letter, which say where to send it, and keep copies of everything.

Some plans also review where the scan will be done. Premera’s reviews of CT, MRI and MRA requests added site of care starting January 1, 2026. If your request was denied because of the location, ask which locations would be approved.

Traditional Medicare rarely uses prior authorization. Medicare Advantage plans can require it before a service is covered.

• Not enough time or treatment first. Guidelines can call for a period of conservative care before advanced imaging. For new low back pain with no warning signs, the American College of Radiology (ACR) says “Imaging is typically not warranted in this setting.” But patients who have failed 6 weeks of conservative therapy should be imaged if they may need surgery or a procedure, or if the diagnosis is still unclear.
• Extra steps a plan adds. In 2022, federal investigators found Medicare Advantage plans had denied requests using criteria not in Medicare’s rules, such as requiring an x-ray before approving more advanced imaging. Since 2024, Medicare Advantage plans may use their own criteria only when Medicare’s are not fully established, and must make them public.
• Documentation the reviewer did not see. The same report found plans saying requests lacked documentation when the existing records were sufficient.
• The wrong version of the scan. Small differences matter. In the ACR’s low back pain criteria, for patients who may need surgery or a procedure after 6 weeks of treatment, an MRI of the lower spine without contrast dye is rated “Usually Appropriate”, while the same MRI with contrast is rated “Usually Not Appropriate.” If the order, the request and the denial describe different scans, ask the office to correct it. See billing and coding errors.
• The location. The scan may be approved at some facilities and not the one on the request.

The ACR Appropriateness Criteria are evidence-based guidelines that rate which imaging test fits a clinical situation. They are reviewed every year by expert panels, and the ACR also publishes short summaries written by patients, for patients.

Review companies may apply their own guidelines. Premera’s reviews, for example, use the review company’s own “Clinical Appropriateness Guidelines for Radiology”.

So ask for the exact criteria the reviewer applied. Employer plans must provide the guideline or a free copy on request, and Medicare Advantage plans must post any internal criteria online.

Medicare once planned to require doctors to consult appropriate-use criteria before ordering advanced imaging for Original Medicare patients. CMS paused that program and rescinded its rules effective January 1, 2024, and it has not set a date to restart it. Doctors no longer report those consultations on Medicare claims.

Ask the ordering doctor’s office to send, or send yourself:

• Office notes with the date symptoms began and how they have changed.
• Exam findings the doctor recorded, especially any new weakness, numbness or other change.
• Treatments already tried, with dates: physical therapy visits, medications, injections.
• Reports from earlier imaging, such as X-rays or ultrasound.
• The exact order: body part, with or without contrast, and the procedure code.
• A short letter from the ordering doctor explaining how the result will change your care, such as whether you are being considered for surgery or a procedure.
• The denial letter and the criteria the reviewer used.

With an employer plan you can also ask for free copies of everything relevant to the claim, including the reviewer’s notes. Compare those notes with your records to see what the reviewer may have missed.

If waiting for a standard decision could seriously jeopardize your life, your health or your ability to regain maximum function, ask for an expedited review and have your doctor say so. For employer plans, a claim is urgent if a doctor who knows your condition says it is, and urgent appeals are decided within 72 hours. The ACR criteria treat some situations, such as suspected cauda equina syndrome, separately from routine back pain.

For the first decision, Medicare Advantage plans must answer expedited requests within 72 hours and, as of 2026, standard prior authorization requests within 7 calendar days. Employer plans have up to 15 days for non-urgent requests.

If the plan upholds the denial, outside review comes next. Insurers in all states must offer external review, decided within 72 hours when expedited, and a Medicare Advantage plan must send an upheld denial to an independent reviewer. See the deadline rules for Medicare Advantage, Original Medicare, employer plans, Marketplace plans and Medicaid.