An MRI scan is painless and involves lying still inside a large tube-shaped machine for roughly 30 to 60 minutes while it captures detailed images of the inside of your body. The experience can feel unfamiliar, though. The machine is loud, the space is tight, and you’ll need to hold completely still. Knowing what happens at each stage makes the whole process easier.
Before You Arrive
Your imaging center will give you specific prep instructions, and these vary depending on what part of your body is being scanned. For most MRIs, you can eat, drink, and take your medications normally. Some abdominal or pelvic scans may require you to fast beforehand, so follow whatever your facility tells you.
The bigger preparation is mental: think through what you’re wearing and what you’re carrying. You’ll need to remove all metallic objects, including jewelry, watches, hair pins, belts, coins, credit cards, and clothing with metal snaps or zippers. Wearing simple, comfortable clothes with no metal (athletic wear works well) saves time at check-in. Transdermal patches like nicotine patches, hearing aids, dentures, and body piercings all need to come off before scanning.
The Safety Screening
An MRI machine uses an extremely powerful magnet, so anything ferromagnetic near it becomes a serious hazard. Before your scan, you’ll fill out a detailed screening form asking about every possible source of metal in or on your body. This covers a long list: cardiac pacemakers, defibrillators, aneurysm clips, cochlear implants, neurostimulators, joint replacements, metal rods or plates in bones, surgical staples, wire sutures, spinal shunts, vascular stents, and even metal fragments from old injuries.
If you’ve ever worked with metal through grinding or fabrication, or had a metallic foreign body near your eye, expect to be asked about that specifically. Some facilities will do an X-ray to check for metal fragments before clearing you for the scan. Tattooed eyeliner or permanent makeup can also contain metallic pigments and needs to be disclosed. None of this is optional. Every implant in your history has to be verified as MRI-safe before scanning can proceed.
How Long the Scan Takes
Scan time depends on what’s being imaged. A shoulder MRI can wrap up in as little as 15 minutes, while a complex abdominal scan can stretch to 90 minutes or longer. Here’s a general range for common scans:
- Brain: 30 to 60 minutes
- Cervical spine (neck): 20 to 45 minutes
- Lumbar spine (lower back): 30 to 60 minutes, or 45 to 90 with contrast
- Knee: 30 to 60 minutes
- Shoulder: 15 to 45 minutes
- Hip: 30 to 60 minutes
- Abdomen: 30 to 90 minutes
Plan to be at the facility longer than the scan itself. Between check-in, the safety screening, getting changed, positioning, and any contrast injection, the full visit often runs 30 to 60 minutes beyond the actual imaging time.
What It’s Like Inside the Machine
A standard MRI bore (the tunnel you slide into) is about 60 centimeters, or roughly 24 inches, in diameter. That’s close quarters. You’ll lie on a padded table that slides into the tunnel, and depending on which body part is being scanned, you may go in headfirst or feetfirst. A brain MRI, for example, means your head enters first and sits inside a frame-like coil. A knee MRI might only require your lower body to be inside the bore, with your head and shoulders outside.
The machine is loud. It produces a series of rhythmic banging, buzzing, and clicking sounds as the magnets cycle through different sequences. You’ll be given earplugs, and many facilities also provide headphones so you can listen to music during the scan. Even with hearing protection, the noise is noticeable.
Staying still is the single most important thing you’ll do. Movement blurs the images, and blurry images may mean repeating sequences or even the entire scan. The technologist will tell you when each sequence starts and roughly how long it lasts. Some sequences run a couple of minutes, others five or six. Between sequences, you can usually relax slightly, but avoid shifting your position.
How You Stay in Contact
You won’t be alone. The technologist operates the machine from a control room with a window looking directly into the scan room, and you’ll have an intercom so you can talk to each other throughout the exam. You’ll also be given a squeeze bulb to hold in your hand. Pressing it triggers an alarm in the control room, so if you feel panicked, sick, or need to stop for any reason, you can signal immediately without needing to speak. The scan can be paused or stopped at any point.
If You’re Claustrophobic
Feeling anxious in the MRI is common, and there are real options beyond just toughing it out. Wide-bore machines have a 70-centimeter opening (about 10 centimeters wider than standard), and facilities report that roughly 99% of claustrophobic patients tolerate these machines without difficulty. Open MRI machines go further, removing the tube entirely so the sides or ends are open. The tradeoff is that open machines sometimes produce lower-resolution images and take longer, though newer wide-bore designs have largely closed that gap.
If you know you’re claustrophobic, call the imaging center ahead of time. Many can schedule you on a wide-bore machine specifically. Some doctors will also prescribe a mild sedative to take before the scan. If you go that route, you’ll need someone to drive you home.
Contrast Dye
Some MRI scans require an injection of a contrast agent, a gadolinium-based liquid delivered through an IV in your arm partway through the scan. The contrast makes certain tissues, blood vessels, or abnormalities show up more clearly on the images. You may feel a brief cool sensation when it’s injected, and some people notice a metallic taste.
Adverse reactions are rare. In a study of nearly 18,000 patients, only 0.17% experienced any reaction at all, and every one of those reactions was classified as mild. The most common complaints were rashes or hives, nausea, and anxiety. Severe allergic reactions to gadolinium are extremely uncommon, but if you’ve had a prior reaction to MRI contrast, let your team know ahead of time.
MRI During Pregnancy or Breastfeeding
MRI is considered safe during pregnancy, including the first trimester, because it doesn’t use ionizing radiation. The American College of Obstetricians and Gynecologists and the American College of Radiology both confirm that no special restrictions apply to any trimester. That said, gadolinium contrast is handled more cautiously in pregnant patients because it can cross the placenta, so it’s typically reserved for situations where the diagnostic benefit clearly outweighs the uncertainty. If you’re breastfeeding, gadolinium contrast is not a concern. You do not need to pump and dump or interrupt breastfeeding after receiving it.
Getting Your Results
The technologist running the scan cannot interpret the images or share results with you on the spot. A radiologist reviews the images and writes a report that goes to the doctor who ordered your scan. Historically, most MRI reports were completed the same calendar day as the scan. More recently, turnaround times have stretched, and a growing share of reports take a day or more. In practice, you can generally expect to hear from your doctor within one to three business days, though it varies by facility and the urgency of your case. Some patient portals now release radiology reports directly, so you may see the written report before your doctor calls to discuss it.