Preparing for an MRI mostly comes down to removing anything metal from your body, wearing the right clothing, and knowing whether your specific scan requires fasting. Most of the preparation happens the day of your appointment, but a few things are worth thinking about ahead of time.
What to Wear and What to Leave Home
The safest approach is to dress in simple, metal-free clothing. Cotton or linen works well. Avoid shoes with steel toes, metal shanks, or magnetic closures. Leave hairpins, barrettes, and any metal hair accessories at home. Jewelry, watches, bracelets, and rings should stay home too, even pieces that aren’t magnetic, since they can interfere with image quality or become a safety concern near the powerful magnet.
Most facilities will have you change into a hospital gown and scrub pants regardless of what you wore in, but arriving in simple clothes speeds up the process.
One detail that surprises many people: your underwear matters. Athletic compression wear, sport bras, and any undergarments labeled “antimicrobial,” “anti-odor,” or “heat-retaining” are not safe for the scanner. These fabrics increasingly contain metallic particles woven into the material that are invisible to the eye but can cause burns during the scan. Plain cotton or linen underwear is the safest choice. If your undergarments don’t meet the requirement, you’ll be asked to remove them.
Fasting and Medication Rules
Whether you need to fast depends on what part of your body is being scanned. For MRIs of the abdomen, liver, pancreas, or pelvis, you’ll typically be asked to avoid eating for four hours before the exam. Pelvic floor imaging usually requires a two-hour fast. Brain, spine, knee, and shoulder MRIs generally have no fasting requirement, but always confirm with your imaging center when you schedule.
You can take your regular medications with small sips of water even when fasting is required. If you take diabetes medication or insulin, ask your doctor’s office how to adjust the timing around a fasting window.
The Safety Screening Form
Before your scan, you’ll fill out a safety questionnaire designed to identify any metal inside your body. Some facilities send this electronically up to 30 days before your appointment so you can complete it at home. Filling it out early gives the MRI team time to research any implants or devices and confirm they’re safe for the scanner.
The form will ask about surgical history, implanted devices, metal fragments (from welding, grinding, or shrapnel injuries), and whether you could be pregnant. Answer thoroughly. Items people commonly forget to mention include dental implants, surgical clips or staples from past procedures, intrauterine devices, and joint replacement hardware. Most modern orthopedic implants are MRI-safe, but the team needs to know about them.
Implants and Medical Devices
Medical implants fall into three categories for MRI purposes: safe, conditional, or unsafe. “Conditional” means the scan can happen only under specific conditions, such as using a particular magnet strength or following special protocols. “Unsafe” means the scan cannot be performed while the implant is in place.
If you have a pacemaker, cochlear implant, spinal cord stimulator, or any other implanted electronic device, bring your implant card. This is the wallet-sized card you received after surgery that lists the brand, model, and serial number. If you’ve lost it, contact the manufacturer for a replacement before your appointment. The MRI team needs this information to verify compatibility with their specific scanner.
Some newer cochlear implants, for example, are designed with magnets that can safely reorient themselves inside the MRI’s magnetic field. Older models may require the internal magnet to be surgically removed before scanning and replaced afterward. The difference comes down to the exact model, which is why the implant card is so important.
Tattoos and Permanent Makeup
Tattoos and permanent cosmetics occasionally cause a warming or tingling sensation during an MRI. This happens when the pigment contains iron oxide or other metallic particles. Decorative tattoos tend to cause more issues than cosmetic tattoos, though actual burns are rare, with fewer than 10 documented cases reported over a 26-year review period. The sensation, when it occurs, typically resolves within hours and doesn’t cause lasting damage. Mention any tattoos near the area being scanned to your technologist so they can monitor you during the exam.
If You Have Contrast Dye Scheduled
Some MRI exams use a contrast agent injected through an IV to make certain tissues or blood vessels more visible. The contrast used in MRI is a different substance than the iodine-based dye used in CT scans, so an allergy to CT contrast doesn’t necessarily mean you’ll react to MRI contrast.
If your scan involves contrast, your facility may check your kidney function with a blood test beforehand. The kidneys clear the contrast from your body, and people with significantly reduced kidney function face a higher risk of a rare but serious complication. Patients with normal or mildly reduced kidney function can receive contrast without any special precautions.
If you’re pregnant, contrast is generally avoided unless the scan is medically urgent and the potential benefit clearly outweighs the unknown risk to the fetus. Let your care team know if you’re pregnant or think you might be.
Managing Claustrophobia and Anxiety
The MRI bore (the tunnel you lie in) is typically about 60 centimeters wide, and scans last anywhere from 20 minutes to over an hour. If enclosed spaces make you anxious, you have several options. Ask your referring doctor about a mild oral sedative to take before the appointment. For more significant anxiety, some facilities offer IV sedation, which puts you in a drowsy but not fully unconscious state.
If you receive any form of sedation, you will not be allowed to drive yourself home, return to work, or go to school that day. Arrange for someone to pick you up before the appointment. This person will need to be present at the facility when you’re discharged.
Even without sedation, the scanner is loud. It produces repetitive banging, clicking, and buzzing sounds that can reach the volume of a lawnmower. You’ll be given earplugs or headphones, and many facilities let you listen to music. Knowing this ahead of time helps: the noises are normal and mean the scanner is working.
What to Expect During the Scan
You’ll lie on a padded table that slides into the scanner. A technologist will position you and may place a lightweight coil (a plastic frame) over the body part being imaged. You’ll hold a call button that lets you communicate with the technologist at any time through an intercom.
The most important thing you can do during the scan is stay still. Even small movements blur the images and may mean repeating sequences. For abdominal or chest scans, the technologist will coach you through brief breath-holds, usually lasting 15 seconds or less. You’ll hear instructions through the headphones telling you when to hold your breath and when to breathe normally. If holding your breath for that long feels difficult, let the technologist know. They can often adjust the scan settings to shorten each breath-hold to around five seconds.
Between sequences, you’ll hear silence for a few seconds before the next round of sounds begins. A full exam might include six to ten separate sequences, each lasting a few minutes. The technologist will usually tell you how many are left so you can gauge your progress.