What to expect during your first MRI: step by step (2026 UK guide)

The one-line answer

An MRI is 20 to 45 minutes of lying very still on a padded bed that slides into a large ring-shaped magnet, wearing earplugs, listening to loud rhythmic knocking, holding a squeeze bulb you can press if you want to stop. That is it. No radiation, no needles unless contrast is being used, and nothing you will feel apart from the noise and, sometimes, a brief warmth in the body part being scanned.

The rest of this guide is the boring but useful detail. What to wear, what the safety questionnaire is really asking, what the radiographer needs from you inside the room, what the noises actually mean, how long the different scans take, and what the report looks like when it lands. Everything a first-time patient sensibly wants to know before the day, and almost nothing a clinic bothers to send you in advance.

Before you arrive: what to wear, eat, remove

Wear loose, comfortable clothing with no metal. Cotton joggers, a t-shirt with no metal print or foil transfer, and slip-on shoes are ideal. The clinic will usually offer you a hospital gown to change into and a locker for your belongings, but arriving already in metal-free clothes saves ten minutes and a slightly awkward changing-cubicle ballet.

Leave jewellery at home if you can. Wedding rings that will not come off are usually fine, but every other ring, bracelet, necklace, watch, hair clip, body piercing, hearing aid and dental plate has to come out or off before you go into the scan room. Underwired bras have to go. So do belts, coins, phones, keys and bank cards, all of which the magnet will happily eat or wipe.

You do not need to fast for a standard MRI. Eat and drink normally. Take your regular medication. The exceptions are small-bowel MRI and MRCP scans of the bile ducts, where the clinic will ask you to fast for four to six hours, and some cardiac protocols that ask you to avoid caffeine for a day. If your scan needs a contrast agent (gadolinium), the clinic will have already checked your kidney function beforehand and, in some cases, asked you to stay well hydrated.

Arrival and the safety questionnaire

You arrive fifteen to twenty minutes before your slot. Reception takes your ID, confirms the referral, and hands you the MRI safety questionnaire. This is the most important piece of paper in the building. Read it carefully and answer every question honestly, because everything on it exists because it has, at some point, hurt somebody.

The questionnaire is asking about anything ferromagnetic that could be pulled by the magnet or heated up by the radio waves. In particular:

• Cardiac pacemakers, implantable defibrillators and neurostimulators. Many modern devices are MRI-conditional but the clinic has to know the exact make and model in advance.
• Cochlear implants, drug pumps and hearing-aid implants.
• Aneurysm clips, coils, stents and heart valve replacements. The vast majority are safe; a small number of legacy clips are not.
• Metal fragments in or near the eye, common in metalworkers and welders. An orbit X-ray may be needed first.
• Any surgery in the last six weeks that used metal implants, plates or wires.
• Pregnancy or possible pregnancy. MRI is generally safe in pregnancy but is used cautiously, and gadolinium contrast is usually avoided.
• Kidney function, if contrast is planned. You will typically be asked about a recent eGFR blood test.

You will also be asked to fill out any tattoos, permanent makeup, IUDs and dental work. Almost none of these are a problem, but the radiographer needs the full picture. If in doubt, tell them. It is far easier to check a device sticker in the file than to abandon a scan.

Inside the scanner: what actually happens

The scan room is quiet, cool and dominated by the scanner itself, a large cream-coloured ring roughly the height of a small car. The radiographer positions you on the padded bed. Which end of you goes in first depends on what is being scanned: for a brain, spine or neck MRI you go in head-first; for a knee or ankle you often go in feet-first, which many people find far less claustrophobic than they were expecting.

A soft, plastic-cased receiver coil is placed over or around the body part being scanned. This is what actually picks up the MRI signal, and it is why the scan of your knee looks nothing like a full-body X-ray. You are given a pillow for your head, a wedge or bolster under your knees to take the pressure off your lower back, ear plugs, over-ear headphones, and the squeeze bulb (sometimes called a panic button) that you keep in your hand.

The radiographer runs you into the bore, retreats to the control room next door, and speaks to you through the headphones. You can hear them clearly; they can see you at all times through a window and via cameras. They will tell you what is coming, how long the next sequence is, and whether it needs a breath-hold. Between sequences you can wiggle your toes and swallow. During a sequence you should stay as still as you can manage. Movement is the single biggest cause of a scan being repeated.

If contrast is planned, a cannula goes in your arm before you are positioned. The gadolinium is injected part-way through the scan, usually by a hand-controlled or automatic pump. You may briefly feel a cool sensation up the arm and, occasionally, a very short metallic taste. Neither is unusual.

The noises: why they are loud and what they mean

MRIs are famously loud, and knowing why makes them noticeably less alarming. The magnet itself, the huge outer ring, is silent. The noise comes from a second set of coils inside the machine called gradient coils, which are switched on and off very rapidly to encode the position of the signal. Every time a coil switches, it flexes microscopically inside its housing and rings like a bell. Different sequences drive the coils in different patterns, which is why the noise changes from a slow knocking to a rapid buzz to a high-pitched whine.

Peak volumes inside the bore routinely exceed 100 dB, which is why ear plugs plus over-ear headphones are the UK standard rather than a nicety. Most clinics will play music of your choice through the headphones between and even during sequences. Some newer scanners run “quiet” protocols that reduce the peak volume by around 10 dB, worth asking about if you are noise-sensitive.

How long each scan actually takes

The time you spend on the scanner bed depends entirely on what is being imaged and how many sequences the radiologist has asked for. The typical UK ranges in 2026:

Add ten to twenty minutes on either side for arrival, changing, safety checks and, if contrast is used, cannula placement and post-scan observation. A “30-minute knee MRI” is really an hour of your day, door to door.