MRI Education Guide

How MRI Works

MRI scanners use powerful magnets to create a magnetic field around the body. This field aligns hydrogen atoms (which are abundant in water and fat tissue) in a specific direction. Radio wave pulses are then sent into the body, temporarily disturbing this alignment. When the radio waves are turned off, the hydrogen atoms return to their original position and emit signals. A computer processes these signals and constructs detailed cross-sectional images of internal structures.

MRI does not use ionizing radiation, which distinguishes it from X-ray and CT imaging. This is one reason MRI is frequently used for soft tissue evaluation, brain and spinal cord imaging, joint assessment, and abdominal/pelvic studies. MRI typically takes longer than CT — from approximately 30 to 75 minutes or more depending on the study — and requires the patient to remain still during image acquisition.

MRI equipment comes in varying magnetic field strengths, commonly 1.5 Tesla (T) and 3T. Higher field strength generally allows for higher image resolution and shorter scan times, though 1.5T is clinically sufficient for most diagnostic purposes. Open MRI machines use lower field strengths and may be preferred by patients with claustrophobia, though image quality may differ. According to the FDA, MRI equipment varies significantly in design, and patients should follow all facility safety screening requirements.

What MRI May Be Used to Evaluate

A licensed provider — not a patient or educational resource — determines whether an MRI is appropriate for any given clinical situation. Depending on a patient's symptoms, history, and prior evaluation, a provider may consider MRI for evaluation of various body areas. Common areas where MRI may be considered include:

This list is for educational purposes and does not indicate that MRI is appropriate for any individual patient or clinical scenario. Clinical appropriateness is determined by a licensed provider.

What MRI Cannot Do

• 1MRI produces images that must be interpreted by a trained radiologist or clinician. The scan itself does not provide a diagnosis.
• 2MRI has limited ability to image dense bone cortex (CT or X-ray is generally preferred for cortical bone detail).
• 3MRI does not image air-filled structures (lungs) well — CT is preferred for most pulmonary evaluation.
• 4MRI cannot be used safely in patients with certain metal implants, pacemakers, or other contraindicated devices without facility safety screening and clearance.
• 5MRI takes significantly longer than CT and requires patient cooperation to minimize motion artifact.
• 6MRI results do not replace clinical evaluation, physical examination, or provider judgment.

Why Imaging Centers Require a Provider Order for MRI

Most outpatient MRI facilities, hospital imaging departments, and independent imaging centers require a valid provider order before scheduling an MRI. According to RadiologyInfo.org (a patient education resource jointly published by the American College of Radiology and the Radiological Society of North America), provider orders document the clinical indication for the exam, identify the requesting provider, and support insurance billing and quality assurance processes.

A valid MRI order typically includes: the specific exam type, the body part or region, contrast instructions (with or without), the clinical indication or ICD code, the ordering provider's name and NPI, and the results destination. Facilities may reject orders that are incomplete or not in their required format.

MRI With and Without Contrast

Some MRI studies are ordered "without contrast," some "with contrast," and some "with and without contrast" in sequence. The decision about whether contrast is appropriate is made by the ordering provider based on clinical indications and the specific diagnostic question.

Gadolinium-based contrast agents (GBCAs) are administered intravenously and can improve visualization of certain tissues. For patients with impaired kidney function, gadolinium contrast carries a risk of nephrogenic systemic fibrosis (NSF), a serious but rare condition. According to the FDA, gadolinium retention in the body has been detected even in patients with normal kidney function. Patients with kidney disease, diabetes, or other conditions may need eGFR lab testing before contrast imaging.

General MRI Preparation Guidance

Specific preparation requirements vary by facility and by the type of MRI ordered. Patients should ask their chosen facility for written preparation instructions. General considerations include:

• Remove all metal jewelry, piercings, and accessories before the scan.
• Inform the facility of all metal implants, pacemakers, cochlear implants, surgical hardware, or foreign bodies before scheduling.
• Most MRI scans do not require fasting — confirm with your facility based on the specific study.
• Abdominal/pelvic MRI scans may require specific dietary restrictions — ask your facility.
• Patients with claustrophobia should inform the facility in advance. Facilities may offer open MRI options, sedation, or other accommodations.
• Wear comfortable, loose-fitting clothing without metal zippers, clasps, or underwire.

Scheduling and Facility Acceptance

Patients choose their own MRI facility. DOD is not affiliated with any imaging center or facility. Facility acceptance of DOD orders is not guaranteed and depends on the facility's policies regarding telehealth provider orders. Patients should confirm the following with their chosen facility before booking a DOD consultation:

• The facility accepts orders from virtual/telehealth providers.
• The facility's required order format (fax number, required elements, provider type accepted).
• Pricing and payment policies for self-pay or out-of-pocket MRI.
• Availability and wait times for the requested study.
• Whether the facility can receive the order by fax or secure email.

Results and Follow-Up

MRI results consist of a radiology report generated by a radiologist at the imaging facility where the scan is performed. DOD does not perform MRI and does not generate radiology reports. Patients should confirm with their chosen facility how results will be routed — typically back to the ordering provider and/or to the patient directly if requested.

MRI results should be reviewed with an appropriate licensed provider — a primary care physician, specialist, urgent care provider, or the requesting provider. DOD's role ends when the order is issued. Follow-up care, diagnosis, and treatment planning are the responsibility of the patient's treating providers.

Frequently Asked Questions — MRI

Related Education and Order Pages