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Your child's MRI scan under general anaesthetic

Your child’s MRI scan under general anaesthetic

The aim of this website page is to answer some of the questions you may have about your child’s MRI scan under general anaesthetic.

It explains the benefits, risks and alternatives of the procedure as well as what you can expect when you come to hospital.

If you have any questions or concerns, please speak to a doctor or nurse caring for your child.

For information about the general anaesthetic procedure please refer to the leaflet Your child’s general anaesthetic (PDF 100Kb).

Ask your doctor or nurse for a copy or please contact the Knowledge & Information Centre (KIC) on 020 7188 3416.

What is an MRI scan?

MRI stands for magnetic resonance imaging. An MRI scan uses a combination of a strong magnet and radio waves to produce detailed pictures of the inside of your body.

What are the benefits of an MRI scan?

An MRI scan can help to find out what is causing your child’s problem and help your doctor to find the best treatment. An MRI scan provides much more detailed pictures of your child’s body than an ordinary X-ray. It is particularly good at identifying problems in the spine, the brain and in the joints. It is also helpful for looking at other parts of the body, often when other types of scan have not given a full picture. Unlike X-rays and CT (computerised tomography) scans, MRI scans do not use radiation.

Are there any risks?

MRI is a very safe procedure for most patients. However, patients with heart pacemakers and certain other surgical implants, for example a cochlear implant, cannot be scanned. You will be asked to complete and sign a safety questionnaire for your child before their scan, to make sure it is safe for them to be scanned. Your child may also need to have an injection of contrast agent (dye) for their scan, which can very rarely cause an allergic reaction. Please see the dedicated section later in this leaflet for more information.

Are there any alternatives?

If your child cannot have a scan, the radiologist (a specialist doctor trained in studying scans and X-rays) may suggest an alternative type of imaging.This could be a CT scan or an ultrasound scan.

What do I have to do to prepare my child for the scan?

Please follow the preparation details in the information leaflet Your child’s general anaesthetic.

What happens before the scan?

Before your child is given the anaesthetic, the radiographer (a specially trained member of the radiology team who performs the MRI scan) will go through your child’s safety questionnaire with you.

You will be given the opportunity to ask the radiographer any questions you have. Your child will be given the anaesthetic in the anaesthetic room, which is next to the MRI scanner. Once asleep, your child will be taken into the scanner. The scanner is a short tunnel and, when the scanner is working, it makes a loud banging noise. We will give your child headphones to wear, to protect their ears while they are asleep.

Will my child need an injection of contrast dye during the scan?

If we are scanning certain areas of your child’s body, we may need to give them an injection of contrast dye. This shows up on the scan and gives us more detailed pictures, particularly of your child’s blood vessels. The injection will be given through a cannula (plastic tube) which a doctor will place in a vein in your child’s arm for the general anaesthetic procedure. The contrast dye contains gadolinium, which may, occasionally, cause allergic reactions. The most common allergic reactions are headaches, nausea and vomiting, sneezing, wheezing, runny nose, eye irritation, itching, hives, skin rash, swelling of the face, mouth, hands, feet or throat, difficulty in breathing, and low blood pressure.

Before the scan we will check whether your child has had any previous allergies. If you would like more information about the injection, please ask the radiographer before your scan. If your child has any problems with their liver and/or kidneys please raise this with the medical team on your child’s admission, as extra tests may be required before administering any contrast.

How long will the scan take?

This depends on which part of your child's body is being scanned and the information that the doctor needs. The radiographer will tell you how long he/she expects your child's scan to take. The whole procedure can take one to two hours on average.

Will my child feel anything?

The scan should be completely painless.

What happens afterwards?

As soon as the scan is finished, your child will be taken to the recovery room. Here, specially trained recovery nurses will closely monitor your child. You will be taken to the recovery room as soon as your child starts to wake up. The pictures taken during the scan are carefully studied by the radiologist who will produce a detailed report. If your child had the injection of contrast dye, very rarely an allergic reaction can occur up to two days after the scan (please read the section of this leaflet, Will my child need an injection of contrast (dye) during the scan? for allergic reactions to look out for).

If this happens, please contact the ward where your child was admitted for advice immediately. Alternatively, contact your local emergency department (A&E).

When will I get the results?

The results will be sent to the doctor who referred your child for the scan – usually a hospital specialist. You will get the results of the scan at your child's next clinic appointment. For more urgent problems, they may be available sooner.

Useful sources of information

See further information about having an MRI scan.

You can also find further information here about your child having an anaesthetic.

Contact us

If you have any questions or concerns about the MRI scan under general anaesthetic, or the contrast dye injection, please contact the doctor who referred your child for the scan.

If you have any questions about your child’s appointment and admission for the scan, please telephone 020 7188 9098 (Monday to Friday, 9am to 5pm).Outside these hours, please leave a message on the answer phone. 


Leaflet number: 2728/VER5
Date published: February 2019
Review date: February 2022
© 2019 Guy’s and St Thomas’ NHS Foundation Trust
A list of sources is available on request 

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