An MRI or CT order looks simple on a schedule. Behind it sits one of the most failure-prone authorization workflows in a practice: the scan usually cannot be performed until a payer — or a benefits manager working for that payer — agrees the study is medically necessary, and the approval is tied to a specific procedure, site, and window of dates. When any piece is wrong, the patient is rescheduled and the scanner slot is lost.
This guide covers prior authorization for advanced imaging only — MRI and CT — from the ordering note to reauthorization. For the broader service, see our prior authorization services page. One rule runs through everything below: imaging authorization criteria vary by payer and by plan, and often by the benefits manager the plan has delegated to. No single payer’s checklist is universal.
Why imaging authorization fails so often
In the Experian Health State of Claims 2026 survey of 204 healthcare professionals in finance, billing, registration, reimbursement, claims and collections roles, difficulty obtaining prior authorization was cited by 25% of respondents as one of their top three denial reasons, tied with code inaccuracy errors (Experian Health, via Becker’s Hospital Review).
The delay is also not only the payer’s decision time. In an MGMA Stat poll of medical group leaders (Sept. 1, 2026, 178 applicable responses), 44% said turnaround in 2026 was slower than in 2025, 40% said it was about the same, and only 7% said it was faster — even though new federal decision deadlines took effect on January 1, 2026. Respondents pointed to the work around the decision: determining whether authorization is required, assembling documentation, checking status, peer-to-peer reviews, and appeals. That surrounding work is where an ordering office has the most control.
Step 1: The ordering note is the authorization record
An imaging authorization is decided from the ordering documentation, not from the scan itself. Reviewers compare the request against medical-policy criteria, and the note has to show why this study, for this patient, now:
- The clinical question the study must answer. “Rule out mass” is weaker than the symptom pattern, examination findings, and what changes in management based on the result.
- Relevant history and prior work-up. Many imaging policies expect prior conservative treatment, plain imaging, or laboratory findings to be documented first. What is required depends on the body part, diagnosis, and payer policy — check the criteria for the study requested rather than assuming a standard list.
- The exact study requested. Body part, laterality where relevant, and with contrast, without contrast, or both. An approval is issued for specific procedure codes; a study performed differently from the one approved can require an amendment beforehand, not a correction after.
- Diagnosis coding that matches the note. Code to the documented signs, symptoms, and confirmed conditions; a vague diagnosis invites a medical-necessity denial.
Where the ordering provider and the imaging facility are different organizations, agree in writing who owns the authorization. Both sides assuming the other handled it is a recurring cause of performed-but-unauthorized scans.
Step 2: Check the payer’s criteria — and who actually decides
Before submitting, answer three questions for this patient:
- Is authorization required for this study in this setting? Requirements commonly differ by setting. In several delegated programs, for example, imaging performed during an emergency visit, observation stay, or inpatient stay is excluded, while the same study in an outpatient setting requires approval. That pattern is an example, not a rule — confirm it per plan.
- Who decides — the health plan or a radiology benefits manager? Many plans delegate advanced imaging authorization to a specialty benefits manager. The portal, the clinical guidelines applied, and the peer-to-peer phone number may all belong to the manager, not the plan named on the card. Submitting to the wrong one loses days.
- Which medical policy applies? Pull the current policy for the requested study. Policies specify the indications, prior-treatment or prior-imaging expectations, and documentation elements reviewers look for. Policies are revised; last year’s criteria sheet is not a safe reference.
Pair this check with eligibility verification on the same day: terminated coverage or a plan change invalidates work done against the old coverage.
Step 3: Submit, record, and track — the imaging authorization log
Submit through the channel the deciding organization specifies — usually its portal — and record the case the moment it is submitted. A one-line-per-case log prevents most imaging authorization losses. Track these fields for every case:
- Patient, date of birth, member ID — prevents filing under the wrong member record.
- Ordering provider and rendering facility — shows who owns the next action.
- Study requested (codes, body part, contrast) — the approval must match what is performed.
- Payer and deciding organization (plan or benefits manager) — portal, guidelines, and peer-to-peer contact differ.
- Date/time submitted; channel; case number — starts the decision clock; anchors status checks.
- Standard or expedited, with the clinical basis — expedited handling must be justified.
- Requests for additional information, with dates sent — most delays sit here, outside the decision window.
- Decision: approved, modified, or denied, with the specific reason — a modified approval is not the approval requested.
- Approved codes, site, and validity window — scheduling outside the window voids the approval.
- Peer-to-peer date, reviewer, and outcome — creates the record an appeal relies on.
- Date performed and date the claim was submitted — closes the loop between authorization and claim.
Review the open-case list daily: a case in “additional information requested” is pending with you, not the payer.
What the federal timelines do — and do not — cover
Under the CMS Interoperability and Prior Authorization final rule, as described by MGMA, Medicare Advantage organizations and several Medicaid and CHIP payers must generally send decisions for non-drug medical items and services within 72 hours (expedited) and seven calendar days (standard), beginning January 1, 2026, and must give a specific reason for a denial. Affected payers must also implement Prior Authorization APIs by January 1, 2027 and publicly report aggregate authorization metrics annually.
Three limits matter for imaging workflows. First, these requirements bind the impacted payers named in the rule — they do not set the timeline for every commercial plan, so do not promise a patient a decision date from the federal rule alone. Second, the clock covers the decision once a complete request is received; time spent determining whether authorization is required, gathering records, and answering follow-up questions sits outside it — which is why MGMA respondents still experience slow turnaround. Third, an approval is not a payment guarantee: eligibility on the date of service, coding, and the match between the study approved and the study performed are still checked at adjudication.
Step 4: Peer-to-peer reviews — prepare like the record will be read back
A peer-to-peer review is a conversation between the ordering clinician and a physician reviewer for the payer or its benefits manager, usually offered after an initial denial. It is scheduled inside a limited window stated in the denial notice, and at some organizations a missed appointment cannot be rescheduled — the case moves to a formal appeal. Treat scheduling the call as urgent.
Prepare the clinician with a one-page brief: the clinical question, findings so far, the specific policy criterion the case meets (or why it is an exception), prior treatment or imaging completed, and what the study will change in management. If the denial stands, ask what documentation or alternative study would change the outcome, note the reviewer’s name and date, and file it in the log — that record becomes the foundation of a written appeal. Our prior authorization denials guide covers the appeal steps that follow.
Step 5: Expiration and reauthorization
Imaging approvals expire. Validity windows are set by the deciding organization and vary — the approval letter for the case is the only reliable source. Three habits prevent expiration losses:
- Schedule inside the window at approval, not after. If the first available appointment falls outside it, request an extension or a new authorization before the original expires.
- Amend before you change. If the plan changes — different body part, contrast, or modality — get an amendment approved before the study is performed. Performing first converts an approved study into an unauthorized one.
- Re-verify before the appointment. Eligibility, plan, and authorization status can all change between approval and appointment. A confirmation check is cheaper than a denial.
How imaging authorization failures stall everything downstream
An authorization defect does not stay in the authorization queue. The appointment is cancelled or the scan is performed at financial risk, and rescheduling pushes the patient’s work-up — and every decision that depends on the result — back by the length of the new wait. If the study is performed without a valid approval, the claim denies for no authorization, leaving an appeal built on a defective record or a write-off. For imaging-heavy practices, authorization discipline is scheduling and revenue discipline at once — and a core part of sound radiology billing.
Frequently asked questions
How long does prior authorization for an MRI take?
It depends on the plan, the deciding organization, and how complete the first submission is. For Medicare Advantage and several Medicaid and CHIP payers, federal requirements effective January 1, 2026 set maximum decision timeframes of 72 hours for expedited requests and seven calendar days for standard requests once a request is received. Other plans set their own timeframes. Assembling documentation and answering follow-up questions adds to the total.
Who submits the authorization — the ordering provider or the imaging center?
It varies by plan and delegated arrangement. In many benefits-manager programs the ordering provider submits the request, and the rendering facility confirms an approval exists before performing the study. Confirm the division of responsibility for each plan, in writing between the two offices.
Does every MRI or CT need prior authorization?
No. Requirements vary by payer, plan, study, and setting; some studies in emergency, observation, or inpatient settings are excluded in some programs, while the same study in an outpatient setting requires approval. Check before scheduling.
What happens if the authorization expires before the scan?
The study is no longer covered by that approval. Contact the deciding organization for an extension or a new authorization before performing the scan, and document the new window in the log.
Can the study be changed after approval — for example, adding contrast?
Only within what the approval allows. Some programs permit defined substitutions; most other changes require an amendment approved before the study is performed. Check the approval letter for the case.
A peer-to-peer upheld the denial. What next?
File the formal appeal described in the denial notice, using the denial’s specific reason, the peer-to-peer record, and any documentation the reviewer identified. Track the appeal deadline in the denial letter — it is plan-specific.
Conclusion
Imaging prior authorization works when the ordering note is written for the reviewer, current criteria are checked case by case, every submission is logged with its validity window, and peer-to-peer and reauthorization deadlines are treated as schedule deadlines, not paperwork. That requires checking each payer’s rules, per patient and per plan, before the scanner is booked.
If MRI and CT authorizations are a recurring source of reschedules and denials, a free medical billing audit can show where the workflow is breaking.
