MRI scan (Magnetic resonance imaging (MRI))
A scan that uses a strong magnet and radio waves (no X-rays) to make detailed pictures of the soft tissues, organs, joints and brain to help diagnose a problem.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- An MRI gives detailed pictures of soft tissues, organs, joints and the brain, and uses no X-rays or radiation.
- A normal scan is reassuring but does not rule out every condition, and it can pick up harmless 'incidental' findings that lead to more tests.
- There is usually no recovery — most people go straight back to normal activities; results normally come as a written report in about 1–2 weeks.
- Tell the team about any metal in your body, a pacemaker or other implant, pregnancy, or kidney problems before you are booked, as these affect safety and whether contrast can be used.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your radiologist will give you advice for your situation.
Gives very detailed pictures of soft tissues, the brain, spinal cord, joints and many organs
People with certain implants (some pacemakers, defibrillators, cochlear implants, clips or metal fragments) where the device is not confirmed MRI-safe.
You lie still in a noisy tunnel for 15–60 minutes. You can talk to the radiographer through an intercom and press a buzzer at any time.
A clear route to your written report and a named person to explain it.
You lie still in a noisy tunnel for 15–60 minutes. You can talk to the radiographer through an intercom and press...
You can normally eat, drink, drive and return to work immediately. If you had medicine to relax (sedation) you...
Drinking normally helps clear the dye. Mild flushing or a metallic taste settles quickly. Seek advice if you get a...
A radiologist reviews the images and sends a report to the doctor who referred you, who discusses the results and...
What is an MRI scan?
An MRI (magnetic resonance imaging) scan uses a strong magnetic field and radio waves to build very detailed pictures of the inside of your body. It does not use X-rays or radiation. It is especially good at showing soft tissues such as the brain and spinal cord, muscles, ligaments, joints, the liver and other organs.
A doctor usually requests an MRI to look into a specific symptom or to check a known problem — for example back pain with nerve symptoms, a suspected ligament tear, or a problem seen on another test. The scan produces images; a radiologist (a doctor who specialises in reading scans) then studies them and writes a report.
An MRI shows structure very well, but a normal scan does not rule out every possible illness, and not every change it finds is important. Some findings are 'incidental' — picked up by chance, often harmless, but sometimes leading to more tests. A scan is one piece of the picture, alongside your symptoms, examination and other tests.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
MRI compared with CT
| MRI | CT | |
|---|---|---|
| Uses radiation | No | Yes (X-rays) |
| Best for | Soft tissues, brain, spine, joints | Bone, lungs, bleeding, quick emergencies |
| Time in scanner | Longer (often 20–60 min) | Shorter (often minutes) |
| Noise / space | Loud; narrow tunnel | Quieter; shorter ring |
| Metal implants | Often a problem — must be checked | Usually fine |
Neither scan is 'better' overall — they answer different questions. Your doctor and the radiologist choose based on what needs to be seen.
Preparing for your scan
- Tell the team in advance about any pacemaker, defibrillator, cochlear implant, metal clips, stents, joint replacements, shrapnel or metal fragments in the eyes, as some are unsafe near the magnet and all must be checked.
- Say if you are or might be pregnant, or are breastfeeding, especially if contrast may be used.
- Mention kidney problems or reduced kidney function — a blood test is sometimes needed before gadolinium contrast.
- Tell them if you have a fear of enclosed spaces (claustrophobia); you may be able to have medicine to relax, bring a companion, or be referred for a more open scanner.
- Remove all metal beforehand: jewellery, watches, hearing aids, hairclips, coins and anything with metal fastenings; you may change into a gown.
- Follow any instructions about eating, drinking or medicines (most scans need no fasting; some, such as certain tummy scans, do).
- Allow time — the scan itself can take from 15 minutes to over an hour, and you must lie still.
What happens
You lie on a flat bed that slides into a short tunnel in the centre of the scanner. A radiographer operates the machine from the next room and talks to you through an intercom; you are given a buzzer to press if you need them.
The scanner is very noisy, making loud knocking and buzzing sounds, so you wear ear plugs or headphones. It is important to keep still, as movement blurs the pictures. If contrast is needed, a small cannula is placed in a vein and the dye is given partway through.
Most scans take 15–60 minutes depending on the body part. You usually feel nothing from the scan itself. Afterwards you can normally eat, drink and carry on as usual straight away; a radiologist reviews the images later and sends a report to the doctor who referred you.
Is this scan right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- People with certain implants (some pacemakers, defibrillators, cochlear implants, clips or metal fragments) where the device is not confirmed MRI-safe.
- When the question is better answered by another test — for example bone detail, acute bleeding or lung problems are often clearer on CT or X-ray.
- Asymptomatic people seeking a whole-body screen, where harms (incidental findings, anxiety, further tests) often outweigh benefits.
- People who genuinely cannot keep still or tolerate the scanner even with support, where image quality would be too poor to help.
Delay or rearrange if…
- You may be pregnant, particularly if contrast is being considered — discuss timing and need first.
- Your kidney function is reduced or unstable and gadolinium contrast is planned, until it has been assessed.
- There is metal or an implant that has not yet been checked for MRI safety.
- Severe untreated claustrophobia, until a plan (relaxing medicine, open scanner or support) is in place.
- Key prior scans or results are missing that would change which scan is needed.
Alternatives to discuss
- No scan, or watchful waiting, if symptoms are mild and a scan would not change management.
- CT scan, which is faster and better for bone, lung and acute bleeding.
- Ultrasound, which uses no radiation and is good for many soft-tissue, abdominal and pelvic questions.
- X-ray for bones and chest as a first-line test.
- Going through an NHS pathway rather than self-funding, where time allows.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Benefits
- Gives very detailed pictures of soft tissues, the brain, spinal cord, joints and many organs
- Uses no X-rays or ionising radiation, so it can be repeated when needed and is often preferred for younger people
- Can help diagnose a problem, plan treatment, or check how a known condition or treatment is progressing
- Can often answer a specific question without a more invasive test
- A normal, reassuring result can reduce the need for further investigation
Risks & complications
- Feeling enclosed or anxious in the tunnel (claustrophobia)
- Discomfort from lying still and the loud noise
- With contrast: a brief cold feeling, flushing, a metallic taste or mild nausea
- An 'incidental' finding picked up by chance that may be harmless but leads to more tests and worry
- A scan that has to be repeated or extended because of movement or unclear images
- A normal scan that gives false reassurance when a problem is present but not visible
- Bruising or discomfort where a contrast cannula was placed
- A mild allergic-type reaction to gadolinium contrast
- A serious allergic reaction to gadolinium contrast
- Nephrogenic systemic fibrosis — a rare scarring condition linked to gadolinium in people with severe kidney failure (now very rare with modern agents and careful screening)
- Injury from unsafe metal or an implant being taken into the scanner — which is why screening beforehand matters
The biggest safety point with MRI is the magnet, not the pictures: certain implants and metal fragments can be dangerous, so honest, careful screening before the scan is essential. With contrast, the main concerns are reduced kidney function and, rarely, allergy. Ask whether contrast is really needed and whether your kidneys need checking first.
Published figures to discuss
MRI itself does not use radiation and serious harm is rare, so most 'rates' relate to contrast reactions, incidental findings and false reassurance rather than the scan. Figures vary by the type of scan, whether contrast is used, the patient's kidney function, and the population scanned. Incidental-finding rates are much higher in whole-body screening of well people than in targeted scans for a symptom.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Serious allergic reaction to gadolinium contrast | Rare — well below 1 in 1,000 injections | Mild reactions (nausea, flushing, brief taste) are more common; severe reactions are uncommon but units are equipped to treat them. | NHS — MRI scan: risks and what happensnhs.ukPublished figure |
| Nephrogenic systemic fibrosis (NSF) after gadolinium | Very rare; essentially limited to severe kidney failure (eGFR under ~30) | Now very rare with modern contrast agents and kidney-function screening; routine scans in people with normal kidneys are not affected. | NHS — MRI scan: risks and what happensnhs.ukSource-linked context |
| Incidental findings on whole-body MRI screening | Reported in roughly 1 in 3 to 1 in 2 healthy people; false-positive findings around 1 in 6 in pooled reviews | Most lead to further tests and anxiety rather than a serious diagnosis; this is a key reason routine whole-body screening is not recommended. | NHS — MRI scan: risks and what happensnhs.ukPublished figure |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
There is usually no physical recovery from an MRI. Most people return to normal activities, work and driving straight away. The main thing you are waiting for is the written report.
- No after-effects at all for most people
- Mild tiredness or relief after lying still in a noisy machine
- A short-lived metallic taste or flushing if contrast was used
- A wait of days to a couple of weeks for the written report, which can feel anxious
Aftercare
- Carry on with normal activities, work and driving unless you were given medicine to relax.
- If you had sedation, do not drive, operate machinery or sign anything important for the rest of the day, and have someone with you.
- Drink fluids normally if you were given contrast, to help your body clear it.
- Watch for any delayed rash, swelling or breathing difficulty after contrast and seek medical advice if it occurs.
- Make a note of when and how you will get your results, and who will explain them.
- Chase the result if you have not heard within the expected time — do not assume no news is good news.
- Bring or ask for a copy of the report and images if you may need them for another opinion.
- Screening form completed honestly (implants, metal, pregnancy, kidneys)
- All metal items left at home or removed
- Someone to drive you home if sedation is planned
- Clear instructions on eating/drinking and medicines
- Date and route for getting your results
- A named contact if you have questions after the scan
⚠ Get urgent help if…
- Difficulty breathing, wheezing or throat tightness after contrast — call for emergency help
- Widespread rash, hives or swelling of the face, lips or tongue after the scan
- Feeling faint, very unwell or having a racing heart after contrast
- Pain, swelling or spreading redness at the cannula site where contrast was given
- Any symptom your team specifically warned you to report
- New or rapidly worsening symptoms while you wait for results — seek advice rather than waiting for the report
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your radiologist gives you.
Results & realistic expectations
A good result is a clear set of images that answers the question your doctor asked — whether that is reassurance that nothing serious is seen, or a finding that explains your symptoms and guides treatment. The radiologist's report is usually ready within about 1–2 weeks, and sooner if urgent.
A normal scan is reassuring but does not prove you are completely free of disease, because MRI cannot show everything and some problems are not visible as structural change. The scan also cannot, by itself, tell you what a finding means for you — that needs your doctor to put it together with your symptoms and other tests.
An MRI is a snapshot in time. It reflects how things look on the day of the scan, so it can become out of date if your symptoms change or a long time passes. Your doctor will advise whether and when a repeat or follow-up scan is useful; repeating it too often without a clear reason adds cost and anxiety without adding value.
Related tests, treatments or support
MRI is often used alongside other tests — for example blood tests, an ultrasound, an X-ray or a CT scan — because each answers a different question. Sometimes a finding on MRI leads to a further targeted scan or a biopsy. Your doctor should explain how the pieces fit together rather than ordering tests in isolation.
Follow-up & long-term care
Results are normally sent as a written report to the doctor who referred you, who then explains them and arranges any next steps — reassurance, treatment, a further test, or a specialist referral. Make sure you know who is responsible for giving you the result and by when, and chase it if you have not heard.
Repeat, follow-on and what comes next
- Scans sometimes need to be repeated or extended because of movement, breathing or unclear images.
- An unclear or 'indeterminate' finding may need a follow-up scan after an interval to see if it changes.
- A finding on MRI may lead to a further targeted scan or a biopsy to find out what it is.
- Comparing with previous scans often matters — bring or request prior imaging where possible.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- A clear route to your written report and a named person to explain it.
- A plan for any incidental or unclear findings, with sensible thresholds for further tests.
- Contact details for delayed contrast reactions or questions after the scan.
- Your images and report made available to you and any other clinician you choose.
- Honest advice on whether and when any repeat scan is actually needed.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- The body part and number of areas scanned, and whether more than one region is imaged
- Whether contrast (gadolinium) is used, including the cannula and the dye itself
- Whether a specialist radiologist reports it and how quickly the report is provided
- Same-day or urgent reporting versus a standard turnaround
- Medicine to help with claustrophobia, or use of an open/wide-bore scanner
- Any follow-up consultation to explain the results
- Whether further scans or a biopsy are needed if something is found
- The radiographer/facility fee and which body part(s) are included
- Whether contrast is included or charged separately
- The radiologist's reporting fee and the expected turnaround time
- Whether a consultation to explain results is included
- What happens (and what it costs) if the scan is inconclusive or needs repeating
- What happens if an incidental finding needs further tests
- The cancellation and rebooking policy
On the NHS? MRI is commonly available on the NHS when a doctor decides it is clinically needed; private scans are mainly used for speed, choice of scan or self-requested screening, and a referral is normally still required.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Not explaining that a normal scan does not rule out every condition.
- Not discussing incidental findings and how they will be handled before the scan.
- Using contrast without checking kidney function or explaining why it is needed.
- No clear plan for who gives the result and by when.
- Selling a whole-body screen without an honest account of false positives and follow-up tests.
Marketing red flags
- Claims that a whole-body MRI 'catches everything' or 'prevents cancer'.
- Promoting screening scans to well people without discussing incidental findings and harms.
- Implying a normal scan guarantees you are healthy.
- Pushing extra body regions or contrast without a clear clinical reason.
- No named clinician to explain results or arrange follow-up.
Choosing a specialist safely
- Check the radiologist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the radiologist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good radiologist will welcome every one of these.
- What specific question is this scan meant to answer for me?
- Will I need contrast, and if so, do my kidneys need checking first?
- What happens if the scan is normal, abnormal, or shows something unexpected?
- Could a different test answer this with less time or cost?
- Who will explain my results to me, and by when?
- If you find an 'incidental' finding, how will we decide whether it needs action?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the radiologist who carries out my scan, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this scan not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Can I have an MRI on the NHS?
Does an MRI hurt or use radiation?
What if I'm claustrophobic?
Why might I need contrast (gadolinium)?
How long until I get my results?
Should a well person have a whole-body MRI screen?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: NHS — MRI scan NHS — MRI scan: risks and what happens Royal College of Radiologists — gadolinium contrast guidance MHRA — gadolinium contrast agents: drug safety information Whole-body MRI for preventive screening: systematic review — PubMed NICE — guidance and topics on imaging
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
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