MRI scan - How it's performed 

How an MRI scan is performed 

A magnetic resonance imaging (MRI) scan is a painless procedure that lasts between 15 and 90 minutes, depending on the size of the area being scanned and the number of images being taken.

Before the scan

On the day of your MRI scan you should be able to eat, drink and take any medication as usual, unless advised otherwise.

In some cases, you may be asked not to eat or drink anything for up to four hours before the scan, and sometimes you may be asked to drink a fairly large amount of water beforehand. This will depend on the area being scanned.

When you arrive at the hospital you will usually be asked to fill out a questionnaire about your health and medical history. This will help the medical staff performing the scan be as sure as possible that you can have the scan safely. Read more about who can and can't have an MRI scan

Once you have completed the questionnaire, you will then usually be asked to give your signed consent for the scan to go ahead.

As the MRI scanner produces strong magnetic fields, it's important to remove any metal objects from your body, including:

  • watches
  • jewellery, such as earrings and necklaces
  • piercings, such as ear, nipple and nose rings
  • dentures (false teeth)
  • hearing aids
  • wigs (some wigs contain traces of metal)

Any valuables can usually be stored in a secure locker.

Depending on which part of your body is being scanned, you may need to wear a hospital gown during the procedure. If you do not need to wear a gown, you should wear clothes without metal zips, fasteners, buttons, underwire (bras), belts or buckles.

Some MRI scans involve having an injection of contrast dye. This makes certain tissues and blood vessels show up more clearly and in greater detail.

It's possible for contrast dye to cause tissue and organ damage in people with severe kidney disease. If you have a history of kidney disease, you therefore may be given a blood test to determine how well your kidneys are functioning and whether it is safe to proceed with the scan.

An MRI scan is a painless procedure, so anaesthesia (painkilling medication) is not usually required. You can ask for a mild sedative to help you relax if you are claustrophobic. If you would like a sedative, you should ask your GP or consultant well in advance of having the scan.

If you decide to have a sedative during the scan, you will need to arrange for a friend or family member to drive you home afterwards as you will be unable to drive for 24 hours.

General anaesthetic (medication that makes you unconscious) is often used when young children and babies have an MRI scan. This is because it is very important to stay still during the scan, which young children and babies are often unable to do when they are awake.

During the scan

An MRI scanner is a short cylinder that is open at both ends. You will lie on a motorised bed that is moved inside the scanner. You will enter the scanner either head first or feet first, depending on the part of your body being scanned.

In some cases, a frame may be placed over the body part being scanned, such as the head or chest. This frame contains receivers that pick up the signals sent out by your body during the scan and it can help to create a better quality image.

A computer is used to operate the MRI scanner, which is located in a different room to keep it away from the magnetic field generated by the scanner.

The radiographer operates the computer, so they will also be in a separate room to you. However, you will be able to talk to them, usually through an intercom, and they will be able to see you at all times on a television monitor.

While you are having your scan, a friend or family member may be allowed to stay in the room with you. Children can usually have a parent with them. Anyone who stays with you will be asked whether they have a pacemaker or any other metal objects in their body. They will also have to follow the same guidelines regarding clothing and removing metallic objects.

To avoid the images being blurred, it is very important that you keep the part of your body being scanned still throughout the whole of the scan until the radiographer tells you to relax.

A single scan may take from a few seconds to three or four minutes. You may be asked to hold your breath during short scans. Depending on the size of the area being scanned and how many images are taken, the whole procedure will take between 15 and 90 minutes.

The MRI scanner will make loud tapping noises at certain times during the procedure. This is the electric current in the scanner coils being turned on and off. You will be given earplugs or headphones to wear.

You are usually able to listen to music through headphones during the scan if you want to, and in some cases you can bring your own CD of music you would like to listen to.

You'll be moved out of the scanner when your scan is over.

After the scan

An MRI scan is usually carried out as an outpatient procedure. This means that you will not need to stay in hospital overnight. After the scan, you can resume normal activities immediately.

However, if you have had a sedative, a friend or relative will need to take you home and stay with you for the first 24 hours. It's not safe to drive, operate heavy machinery or drink alcohol for 24 hours after having a sedative.

Your MRI scan will need to be studied by a radiologist (a doctor trained in interpreting scans and X-rays) and possibly discussed with other specialists. It is therefore unlikely that you will know the results of your scan immediately.

The radiologist will send a report to the doctor who arranged the scan, who will discuss the results with you. Unless they are needed urgently, it usually takes a week or two for the results of an MRI scan to come through.

Page last reviewed: 05/09/2013

Next review due: 05/09/2015


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The 17 comments posted are personal views. Any information they give has not been checked and may not be accurate.

MelRacine said on 23 June 2014

I had an MRI in May. It was really, really easy. The guys were reassuring, answered any questions and made me feel looked after. The machine itself was a little claustrophobic and noisy, but I had both earplugs and ear defenders on, and I closed my eyes and may even have dozed off for a bit. It really wasn't nearly as bad as I'd expected it to be.

What I have found is that the surrounding service is slow and, worse, inconsistent with moving goalposts.

It was four weeks from GP referral to getting MRI.

The guys on the MRI machine said results in 2-3 weeks. GP then said 4 weeks. Chased with X-Ray directly, and they say 5-6 weeks before it even gets sent to the GP..

I understand that the NHS is under-resourced and underfunded, and the slowness I could accept if it were managed well. Manage my expectations and I can manage my life.

(Because I kept putting a decision off in line with the moving goalposts, I am now committed to a short works contract which will no doubt leave me in a great deal of pain, because I cannot take painkillers or other pain management techniques until we know exactly what the issue is. I also don't know if that work will do more damage to what's already there.)

If someone had said that I would have to wait at least three months from the initial referral, or up to eight weeks from the MRI, I could have made interim decisions that would have preserved my own welfare far more effectively.

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Mand7 said on 07 April 2014

Hi all,

Iv been suffering with my back for 7 years one. Been to the doctors, changed doctors etc.

I have had so many different types of medication, an epidural, 2 lots of facet joint injections, physio both private and NHS.
I had to have a new scan as I got 2 different diagnoses from 2 different consultants.
I am now waiting 3 months down the line for my results.

I have tried to chase my results up via my GP and the hospital.

Is this normal?

In the meantime, iv have been back to my GP for more pain relief who refuse to give me any until my results have come back..

I am at the end of my tether, as everyday I'm in constant pain and I'm getting nowhere fast.

What the heck is with the NHS?

Can someone enlighten me as to how long is the average waiting time on getting back results please..

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mmlives said on 07 January 2014

I had my first MRI today for tinnitus. ..I was very nervous but can honestly say it was ok. Yes it was noisy and yes I didn't like the head guard but I kept my eyes shut and counted the noises instead while thinking what I could treat myself with for dinner after ;-) The nurses were very kind and I feel proud that I did it. Just waiting for the results now. Good luck to anyone who's having one too.

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livinglife said on 04 December 2013

I took a client to get one done. This client has down syndrome and other mental issues so I needed to go in with her. I asked what are the risk to me? They were brief in listing to remove any magnetic field or if had past surgery. They had me sign a consent. I wasn't told how long it would take. My glasses are made of medal and I didn't think of taking them off. I was feeling wary more so for myself then the patient. I wonder how others deal with this in their work field. Is it safe to do this frequently? The radiologist are behind a door in another room, looking through a glass window. I welcome any advise.

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Plast said on 08 October 2013

I had a mri scan today and was dreading that flipping tube. I know it was a lot and I feel slightly empty in my bank but worth it as I am claustrophobic. I used the new stand up scanner in harley street. the doctor doing my lower back scan was the nuts. good luck

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pulser said on 01 August 2013

I was sent for M.R.I. scan on a Saturday having waited only a couple of days and was very impressed at being sent for so quickly however I must now wait for results and will not get them until the end of October despite having never been to a doctor in some 16 years!

It does seem to be a long time especially when you are having severe pain.
Just hope it shows up the problem in the back as I have been told that it might not.
Would think it a better idea if radiographer told you the truth as to how long you should expect to be in the scanner. I was told about 15 mins turned out to be 40.

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runwellian said on 21 July 2013

I had an MRI scan of the head after a minor stroke.
There was a lot of concern re vast changes to the 'white matter' in my brain, but to date, one year on, nobody has explained what this means for me?

I asked my consultant who dismissed my request saying 'it was due to age' ... I am worried it is dementia maybe?

The MRI was painless, no need to undress. It can make loud noises, but I closed my eyes, I was so relaxed by the end of it I nearly fell asleep!

Can't find any information on what changes in the brain mean, that would be very helpful as I constantly worry what all the concern is about.

CD's are so cheap today, it would help if they could give patients a CD of the procedure prior to their visit, or make one available to be viewed at the hospital, including other procedures, it helps reduce the anxiety!

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barrowgirly said on 18 July 2013

I went for a brain MRI today , and had no idea they put a cage down over your face. You do feel quite restricted but staff re-assure you, you can see them in the mirror .I took a C.D. which really would have helped distract me but they forgot to put it on, so it was all clicking and clunking noises.I survived and I'm quite a nervous person so I'm sure most people would be fine. They also give you a panic button too.

Now - just waiting for results .I was told ten days to 2 weeks getting them from my G/P.

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OrganisedPauper said on 29 January 2013

I couldn't find any information on head MRIs. Nothing here either. It turns out that for a head MRI you have a cage over your face so you cannot move your head. A 'mild' sedative would not be enough for me to do this. I've had a normal MRI and had to be turned around so I could go in feet first because the other way round I tried and tried but could not contain my claustrophobia. They need information for patients about head MRIs because the procedure is different.

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Kotjara said on 11 January 2013

I was head first in the tunnel, it was very noisy even with headphones and music. Yes a bit claustrophobic but close your eyes and relax its totally harmless and nothing to worry about.
I was there for a shoulder scan wore my own clothes throughout scan---no gown needed

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joe94 said on 04 January 2013

Reading this artical has proven very useful to me as I've got an MRI scan on the 11th January 2013, and I wasn't sure about how they the scan would be performed so this has been very informative and I am glad that I've read it.

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suecrampton said on 14 April 2012

I have had MRI scans including ones with Contrast Dye - they have all been ok. I had both Knees scanned yesterday taking 1 hour. I have read your information above and would like to say I did not have to wear a gown for this MRI and was told I was to go into the Scanner without removing my Jeans with Belt - which has a large heavy buckle on - the MRI was ok and I did not have to have my head in the scanner. I did notice that during the MRI it felt as if the Buckle on the Belt was being lifted - I was interested to read the article above as it says you are to remove items such as these.

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tanialena said on 12 February 2012

I had a pelvic MRI scan yesterday and did not find it at all claustrophobic or that noisy. I felt very relaxed and please to be having it. My fear is the results of it! I know everyone will have a different experience but just remember that this could save your life or at the very least you would know why you are feeling unwell. And bear in mind the longest you will be having the scan is 90 minutes at most.

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Bob61 said on 02 February 2012

I had some reservations about the MRI before i went in but knowing people who had already had this done it did not appear that there would be a problem. However, you cannot stop your mind working overdrive and i felt quite panicky for the first five minutes that i was in there. It is strange being in a tube and a little claustraphobic but i kept thinking positive. I closed my eyes as soon as i went in and had ear muffs on to dampen the noise of the machine. I made my brain active by counting to 100 repeatedly. I did calm down and by the end i was quite relaxed. It just shows how different we all are when placed in a situation never encountered before? There is nothing to worry about so don't let your mind win otherwise you probably won't get through it. Good luck!

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penelopeS said on 02 September 2011

For a breast screening you will lie on your tummy. I found it easier to breath and relax without a pillow under my head. It is noisy, but in between scans it is really helpful to have the occasional strain of your favourite music, so don't forget to take a cd. During the scans you won't be able to hear it, but it will be there when you can hear. I did not expect to have a saline drip and an injection half way through the procedure, so it's useful to know that may happen. It doesn't hurt. I had worn some gruesome jogging pants without zips, but actually I just had knickers and a gown on, so take some nice trousers or a skirt that you can change into after so you can feel better. And once it's all over make sure you and whoever has gone with you go for a treat, even just a cup of coffee, to reward yourself. It all helps to remind you that you are one step further along the road to well being.

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suemcsfl said on 19 June 2011

Before I had my MRI scan I must admit I was terrified I visited my GP who was very reasuring and it was also helpful to discover he had the MRI scan himself. At hospital the staff were brilliant as I suffered from panic attacks I asked for the eye pads and ear phones to be fitted the sight of the scanner was very different than what I imagined not at all scary to look at I sailed through it, in hindsight I would have visited the hospital and looked at the scanner first not at all enclosed, open at both ends I would advise anyone scared of the unknown to still opt for the eye pads and ear phones you can even take your own favourite cd! If I can do it so can anyone else.

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CathieG said on 04 June 2011

Very matter of fact but giving you answers to all the questions you forgot to ask your surgeon.

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