Magnetic resonance imaging (MRI) is a medical imaging technique that uses a strong magnetic field and radio waves to create detailed images of the inside of the body. Doctors use MRI to help diagnose health problems, plan treatments, and monitor progress. MRI is known for its excellent soft-tissue detail and does not use ionizing radiation. Most people can safely undergo MRI, and the procedure is managed by trained professionals to ensure comfort and safety.

MRI is a non-invasive imaging technique that produces high-quality images of organs, soft tissues, and the skeletal system. It uses a powerful magnet and radio waves to scan the body and create cross-sectional images. These images help doctors see differences between healthy and abnormal tissues, which is important for diagnosing many conditions.

MRI is often used to examine the brain, spine, joints, abdomen, and blood vessels. Unlike X-rays or computed tomography (CT) scans, MRI does not use ionizing radiation, making it a preferred imaging option in many situations where repeated imaging is needed and in many pediatric and pregnancy-related clinical scenarios when MRI is clinically appropriate. MRI can also monitor changes over time, such as the growth or shrinkage of tumors, and guide certain treatments or surgeries by providing precise images.

MRI is used to evaluate many conditions affecting the brain, spine, joints, muscles, bones, blood vessels, and internal organs. It is often performed when additional detail is needed beyond what can be seen with X-rays, ultrasound, or CT. Specific uses include:

• Clarifying symptoms: finding the cause of unexplained pain, swelling, or neurological changes
• Detailed imaging: examining the brain, spinal cord, muscles, joints, and many internal organs, where MRI often provides greater soft-tissue detail than other imaging methods
• Monitoring conditions: checking injuries, abnormal growths, or tumor size during and after cancer therapy or tracking disease progression
• Planning procedures: providing detailed maps for surgery or other treatments

Because MRI does not use ionizing radiation, it is often a preferred imaging option for children and people who require repeated imaging. MRI may also be used during pregnancy when clinically appropriate.

Before an MRI, people usually complete a screening form and, in some cases, may need additional tests to help ensure the examination can be performed safely and provide the best images possible. The care team will review the individual’s medical history to check for implants, metal fragments, or previous surgeries. It is important to identify any devices or metal objects that could be affected by the magnetic field, such as pacemakers, implantable cardiac devices, aneurysm clips, neurostimulators, cochlear implants, or medication pumps.

If gadolinium-based contrast material is planned, the care team may evaluate kidney function, particularly in people with known kidney disease or other risk factors for impaired kidney function. They will also ask about prior reactions to MRI contrast agents, allergies and other medical conditions that may affect imaging safety as part of the screening process. For people with possible metal fragments in the eye, such as those who have worked with metal, an X-ray may be needed to check for metal before the MRI. People who are pregnant or breastfeeding should inform the care team before the procedure, as special considerations may apply.

People are asked to remove all metal objects, including jewelry, watches, and clothing with metal parts, because metal can interfere with the image quality of scans and may cause injury. In many cases, people change into a hospital gown to avoid any hidden metal in clothing. People should avoid wearing makeup, nail polish, or other cosmetics that may contain metallic particles if they are near the area being scanned, as they can interfere with MRI image quality.

It is important to inform the care team about pregnancy, breastfeeding, or any health changes before the scan. People who feel anxious or claustrophobic can ask about options such as relaxation techniques, sedation when appropriate, or bringing a support person when permitted by the imaging facility. Some imaging centers offer wide-bore or open MRI scanners or allow music or video during the scan to make the experience more comfortable.

During MRI, an individual lies on a padded table that slides into the scanner, which is usually a long, narrow tube. The procedure is managed by an MRI technologist, who controls the scanner from another room and can communicate throughout the process.

Earplugs or headphones are provided to protect against loud noises from the scanner, which can include banging, clicking, or tapping sounds. These noises are normal and result from the operation of the magnetic coils. The individual must lie still to avoid blurring the images and may be asked to hold their breath for short periods during certain parts of the scan.

For some scans, a contrast agent may be injected into a vein to highlight certain tissues and improve image detail. The injection is usually done through a small needle in the arm or hand, and the care team monitors for any reactions. The scan usually takes between 15 and 60 minutes, depending on the area being examined and the number of images needed.

Throughout the procedure, the care team monitors the individual and can respond if any discomfort or problems arise. Communication with staff is possible via an intercom system or a panic button if needed. After the scan, the table is moved out of the scanner, and the individual can get up and leave the room.

MRI is considered very safe, but some risks and complications can occur.

• Metal objects and implants: The strong magnetic field can move or heat metal objects in or on the body, which may cause injury. Certain implanted devices or metal fragments may make MRI unsuitable or require special precautions. The MRI team will review these factors before the examination.
• Anxiety or claustrophobia: Some people may experience anxiety or claustrophobia due to the confined space and loud noises, but options such as sedation or open MRI machines can help.
• Contrast agents (if used):
• Mild side effects may include nausea, headache, rash, or a metallic taste.
• Rare allergic-like reactions may cause breathing problems, hives, or fainting.
• People with severe kidney disease may be at risk for a rare condition called nephrogenic systemic fibrosis (NSF) after receiving certain gadolinium-based contrast agents. NSF can cause thickening and hardening of the skin and other tissues. The risk is extremely low with the contrast agents most commonly used today.

• Skin irritation or burns: Burns or skin irritation can happen if metal objects or certain clothing are worn during the scan. Certain tattoos, permanent makeup, or metallic cosmetics may rarely cause warming sensations or skin irritation during MRI.

If any symptoms such as difficulty breathing, rash, or feeling unwell occur during or after the scan, people should notify the staff immediately for prompt care. Most allergic-like reactions occur during or shortly after contrast administration, typically within the first hour of receiving a contrast agent, so some imaging facilities may ask people to remain briefly after contrast administration if there is concern for a reaction.

Most people can return to normal activities right away, including eating and drinking as usual. Most people can leave immediately after contrast-enhanced MRI. In some circumstances, staff may ask a person to remain briefly if there are concerns about a reaction. If sedation was given for anxiety or claustrophobia, people should not drive for 24 hours and will need someone to take them home.

Other imaging options may be used if MRI is not suitable. CT scans use X-rays to create images and involve ionizing radiation. CT may be preferred in some situations because it is faster, more widely available, or provides better visualization of certain conditions.

Ultrasound uses sound waves to produce images and is often used for soft tissues and pregnancy. X-rays are commonly used for bones and chest imaging, but they provide less detail for soft tissues. Nuclear medicine scans use small amounts of radioactive material to show organ function and may be chosen for specific conditions.

Special care is taken for certain groups.

• Pregnancy: MRI is generally considered safe during pregnancy when medically necessary because it does not use ionizing radiation. It is used when ultrasound cannot provide enough information. Gadolinium-based contrast agents are generally avoided during pregnancy unless the potential benefit outweighs the potential risk. If contrast is needed, the decision is made on an individual basis after careful consideration by the healthcare team.
• Breastfeeding: In most cases, breastfeeding can continue as usual after receiving a gadolinium-based MRI contrast agent. Only a very small amount of the contrast enters breast milk, and even less is absorbed by the baby. Studies have shown that the amount of contrast received by a nursing infant is extremely low and is not expected to cause harm.
  Current American College of Radiology (ACR) guidance states that interruption of breastfeeding is not required after administration of a gadolinium-based contrast agent. Individuals who remain concerned may choose to express and discard breast milk for 24 hours after the examination, but this is not considered medically necessary.
• Children: MRI is safe for children, but they may need extra help to stay still during the scan. Sometimes, sedation or anesthesia is used to help young children remain calm and still during the scan.
• Older Adults: Older adults can safely undergo MRI. Because kidney function may decline with age and can affect contrast administration decisions, it may be checked before certain contrast-enhanced MRI examinations.

After MRI, the images are reviewed by a radiologist, who sends a report to the doctor who ordered the scan. A follow-up appointment to discuss results and next steps may be necessary. If any side effects or complications occur, individuals should contact their care team for advice.

This article was medically reviewed in September 2026.