MRI (magnetic resonance imaging) Scans

Whether you are having an MRI scan as a planned or an emergency procedure, you should have sufficient explanation before you sign the patient questionnaire and consent form.

What is an MRI?

MRI (magnetic resonance imaging) is the name given to a technique which uses a magnetic field and radio waves, together with an advanced computer system. It builds up a series of images, each one showing a thin slice of the area being examined.

The large machine is about four feet long and the area of interest is positioned in the centre.

These images are very detailed. They can show both bones and soft tissues in the body and provide a great deal of information. Using the computer, the ‘slices’ can be also be obtained in any direction.

MR images allow physicians to evaluate parts of the body and certain diseases that may not be assessed adequately with other imaging methods such as x-ray, ultrasound, or computed tomography (CT).

Are there any risks?

As far as is known at present, this is an extremely safe procedure. It does not involve the use of x-rays. You are placed in a very powerful magnetic field. If you have any small pieces of metal inside your body, you should inform the radiographer as in some cases you may not be able to have the examination.

If you have a history of metal fragments in your eyes, you may need an x-ray done to prove there are no fragments remaining. If you have a pacemaker, metal heart valves or a metallic clip in your brain, there is a risk that these may be affected during an MR scan, and a different examination will need to be arranged instead.

For female patients, if you are or might be pregnant, you must make sure the doctor referring you or a member of staff in the radiology department knows as soon as possible.

MRI scans are not advisable in early pregnancy unless there are special circumstances.

What happens during the MRI?

You will be taken into the MRI scan room and made comfortable lying on the couch. Pads and pillows may be used to help you stay still and maintain your position during imaging. You may be given a contrast medium (a dye) which helps to produce more detailed images.

The contrast medium will be injected into a vein in your arm, which occasionally causes a warm feeling for a short while. If this is required you may need to have a blood test prior to your scan.

The couch will be moved slowly to position the part of your body being scanned in the centre of the scanner. The radiographers will retire to the control room but you will be able to talk to them via an intercom and they will be watching you all the time. It is important that you remain completely still while the images are being recorded. During the scan, you may well find the machine very noisy and you will be given ear plugs and/or earphones to use. If you feel uncomfortable or worried, do mention it immediately to the radiographer.

How long will it take?

The process of taking the images usually takes about 20–30 minutes and your total time in the department is likely to be about 45 minutes.

Are there any side-effects?

No. You can drive home afterwards and return to work as necessary.

Do I need to have any special preparation?

Usually you don’t need to have any special preparation for an MR scan. Unless you have been told otherwise, you may eat and drink normally before and after the scan.

Can I bring a relative/friend?

Yes, but for safety reasons they may not be able to accompany you into the scan room, unless there are special circumstances.

When you arrive

Please go to the reception desk detailed in your appointment letter. After this you will be shown where to wait until collected by a radiographer or other member of staff.

Upon collection

You may be asked to remove your outer garments and jewellery (except your wedding ring), cash, keys, credit cards and watches etc and place them in a secure locker.

Who will I see?

You will be cared for by a small team including a radiographer who will perform the examination.

Can I eat and drink afterwards?

Yes, you may do so normally.

When will I get the results?

After the scan the images will be examined by the radiologist who will prepare a report on their findings. This will be sent to you referring clinician.

We hope your questions have been answered by this leaflet and your appointment letter, but remember that this is only a starting point for discussion about your examination. Make sure you are satisfied that you have received enough information about the examination, before you sign the patient questionnaire and consent form.

Other sources of Information

Royal College of Radiologists

NHS website
For health advice and information, visit the NHS website:

For information from the NHS about MRI scans please click the button below:

Further information:

This leaflet tells you about having a magnetic resonance imaging (MRI) Scan.