MRI Scan for Children Under General Anaesthesia

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 the 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 the joints. It is also helpful for looking at other parts of the body, often when other types of scans have not given 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 (electronic device in the ear), 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 – this is explained later in this leaflet. The MRI monitoring can rarely cause burn injury, but special monitoring is used to try and prevent this.

Are there other alternatives?

If your child cannot have a scan, for example because they have a cochlear implant, 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.

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 MRI room. You will see the anaesthetist to discuss the anaesthetic before coming to MRI.

The scanner is a short tunnel and when the scanner is working, it makes a loud banging noise. We will give your child ear buds to wear, to protect their ears whilst they are asleep.

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

If we are scanning a certain area 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 a more detailed picture of the area, particularly of your child’s blood vessels. The injection will be given through a cannula (small plastic tube) already sited in a vein in your child’s arm/hand or foot. This injection is generally safe. It can very rarely cause an allergic reaction similar to hay fever (runny nose and itchy eyes).

However, 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 test may be needed 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 can tell you how long they expect your child’s scan to take. The whole procedure can take around 1 to 2 hours.

Will my child feel anything afterwards?

The scan should be completely painless, just very noisy. Some children may feel a little achy afterwards because of lying still for a while, asleep for the scan. This will settle but may require a dose of Paracetamol.

When will we get the results?

The results will be sent to your doctor who referred your child for the scan – usually a hospital or community paediatric specialist. You will get the results of the scan either directly from your paediatric doctor or at your child’s next clinic appointment.

Your child’s general anaesthetic

The results will be sent to your doctor who referred your child for the scan – usually a hospital or community paediatric specialist. You will get the results of the scan either directly from your paediatric doctor or at your child’s next clinic appointment.

What is a general anaesthetic?

General anaesthetic involves giving particular medicines to send someone to sleep so they can lie very still whilst the scan is being performed. Specially trained doctors, called anaesthetists, care for all patients having an anaesthetic. All children having a scan under anaesthetic will be cared for by specially trained anaesthetists.

What happens before the scan?

The anaesthetists will meet you and your child before the scan – this may be on the day of the scan or at an outpatients appointment if that is needed. The anaesthetists will talk with you about which anaesthetic technique is most suitable for your child. Please do not hesitate to ask questions if you are uncertain about anything.

You will be asked questions about your child’s medical history including:

• Has your child had an anaesthetic before?
• Does your child have any serious health problems?
• Does your child have any loose teeth?
• What medicines your child is taking?
• Does your child have any allergies?

Asking for consent

Discussing your child’s treatment with you is part of our consent process. We want to involve you and your child in all the decisions about your child’s care and treatment.

How do I prepare my child?

Your child should not have any food for six hours before the scan. This is to make sure their stomach is empty. If food is in the stomach while having a general anaesthetic, there is a high risk of being sick while anaesthetised or when waking up – this can lead to very serious complications. Your child can drink water up until two hours before the scan.

Breast fed babies: you can breast – feed your baby up to four hours before the scan.

Bottle fed babies: you can give your baby bottle-milk up to six hours before the scan (as for food).

Children should continue to drink water or very dilute squash until one hour before the scan.

A ward nurse may put some cream on your child’s hands about one hour before the scan. It is sometimes called ‘magic cream’ because it reduces or stops your child feeling any sharp pain when the anaesthetist puts a cannula into a vein. The cannula allows the anaesthetist to give the anaesthetic as well as any other necessary.

Anaesthetics are the drugs that are used to start and maintain anaesthesia. The anaesthetist gives these.

• Some anaesthetics start with an injection into the vein using a plastic tube called a cannula, but may be continued by breathing gas

• Other anaesthetics start with breathing a gas and then a cannula will be put in when your child is asleep

What are the side effects and complications of having an anaesthetic?

Modern anaesthesia is very safe and serious problems are uncommon. Most children recover quickly and are soon back to normal after anaesthetic. The anaesthetists will use specialist equipment to monitor your child closely throughout the operation. However, some children may still have side- effects or complications.

Side effects are secondary effects of drugs or treatment. They can often be expected but are sometimes unavoidable. Some examples are having a sore throat or feeling sick after the scan. Side – effects usually last only a short time and can be treated with medicines if needed.

Complications are unexpected and unwanted events due to a treatment. Some examples are damage to teeth or an allergy to a drug. The likelihood of complications depends on your child’s medical condition, the type of procedure and anaesthetic used. If there are risk factors specific to your child, these will be discussed with you before the operation.

The scale below is used to help you understand how likely your child is to have a side effect or complication related to anaesthesia:

1 in 10 – someone in your family – very common

1 in 100 – someone in the neighbourhood – common

1 in 1000 – someone in the village – uncommon

1 in 10,000 – someone in a town – rare

1 in 100,000 – someone in a city – very rare

Side effects and complications associated with having an anaesthetic are as follows:

Very common to common (1 in 10 – 1 in 100)

• Nausea and vomiting, headache, drowsiness, dizziness, blurred vision – these may be due to the effects of drugs we use or to lack of fluids. They usually get better within a few hours and fluids or drugs (or both) can be given to treat these problems.

• Sore throat – a tube is placed in the airway to help your child breathe during the scan, which means they may get a sore throat. This is usually only mild and will often settle without treatment.

• Shivering – this may occur because your child gets cold during the scan, due to some of the medicines used, or due to anxiety. Your child can be warmed effectively using a hot-air blanket.

• Bruising and soreness – this can happen around injection and drip sites. It normally settles without treatment, but if the area becomes uncomfortable, the position of the drip can be changed.

Uncommon (1 in 1,000)

• Damage to teeth, lips, gums or tongue – damage may be caused when the breathing tube is put in or taken out, or by teeth clenching during recovery from the anaesthetic.

• Breathing problems – shallow or slow breathing may occur if some of the anaesthetic medicines are still having an effect, or as a result of some pain-relieving medicines. These effects can reverse with other medicines and are unusual after this kind of anaesthetic.

• Behavioural problems – some anaesthetic medicines can cause children to become agitated as they recover from anaesthesia. This will resolve as the medicine wears off. Some children may have nightmares in the few days after an anaesthetic.

• Muscle pains – these may occur as a side- effect of one of the anaesthetic medicines and can be treated with simple pain-relieving medicine, such as Paracetamol.

Rare to Very Rare (1 in 10,000 – 1 in 100,000)

• Damage to eyes – we take great care to protect your child’s eyes but sometimes the surface of the eye can become damaged from contact, pressure or drying of the eye. This is usually temporary and treated with eye drops.

• Serious allergy to drug (anaphylaxis) – allergic reactions will be noticed and treated very quickly. Very rarely, these reactions lead to death even in healthy children.

• Stomach contents getting into the lungs (aspiration) – this can occur if there is still food or drink in the stomach before anaesthesia. This may cause a severe and sometimes life-threatening pneumonia.

• Awareness – becoming conscious during the MRI scan is rare in children. Monitors will be used to record how much anaesthetic is in the body and how the body is responding to it. These help the anaesthetist to make sure your child has enough anaesthetic to keep them unconscious during the scan.

• Nerve damage – nerve damage may be caused by pressure on a nerve during a procedure. Anaesthetists are trained to be aware of nerve damage and take steps to prevent it. If it does occur, it may cause numbness, ‘pins and needles’, muscle weakness or paralysis. However, these are usually temporary and most patients make full recovery after a few days or weeks. Permanent damage is very rare.

• Equipment failure – equipment is tested regularly and monitors are used which give an immediate warning of any problems. Equipment failures rarely have serious effects. All the monitors we use are compatible with the MRI scanner.

• Brain damage and death – brain damage and deaths caused by anaesthesia are very rare and are usually caused by a combination of complications arising together. In a lifetime, an individual is at least 100 times more likely to suffer serious injury or death in a road traffic accident than as a result of anaesthesia.

Information on critical events in paediatric anaesthesia can be found online:

Incidence of severe critical events in paediatric anaesthesia in the United Kingdom: secondary analysis of the anaesthesia practice in children observational trial (APRICOT study):

You may wish to look at the following for further information from the Associate of Paediatric Anaesthetists of Great Britain and Ireland:

What happens after the scan?

As soon as the scan is finished and your child is starting to wake up, your child will be brought back to the ward.

Your child will usually be able to start drinking fluids and then have a light diet within a short time of getting back to the ward.

The pictures taken during the scan are carefully studied by the radiologist who will produce a detailed report.

When will the results be available?

The results will be sent to the doctor who referred your child for an MRI. The results are normally discussed at your child’s next hospital appointment. For more urgent problems, they may be available sooner.

Further information

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

Recommended MRI Websites for you and your child

There are also leaflets for children of different ages available to download from the information for children, parents and carers pages on the College website

• RCoA | Information for Children Parents & Carers

• Rees Bear has an anaesthetic (ages 3-6 years with an adult reader)

• Dennis has an anaesthetic – a Beano comic

• General anaesthesia: a brief guide for young people (age 12 years plus)

Information specific to risks for parents:

Royal College of Anaesthetists – clarification statement on consent and risk of death in children.

NHS Choices – offers health information and advice from specially trained nurses over the phone 24 hours a day.

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