Kids Health Info

MRI scan

  • Magnetic resonance imaging (MRI) is a way of taking detailed pictures of the inside of the body. It is useful for looking at many different parts of the body and often gives more information than X-rays, ultrasounds or CT scans.

    During an MRI scan, the part of the body being scanned will have images taken from several different angles. That's why the images are so detailed.

    MRI uses radio waves in a strong magnetic field to obtain the pictures. The magnetic field and radio waves used in MRI are considered to be safe, even for babies. This is because there is no radiation used in MRI scans, unlike other types of tests like X-rays and CT scans.

    Why does my child need an MRI?

    Your child may need an MRI scan for many different reasons, for example, to:

    • look at the structure or function of parts of the body (anatomy)
    • check for any signs of disease
    • help with planning before an operation
    • help plan follow-up treatment after a procedure.

    What to expect with an MRI scan

    Before an MRI

    One parent or caregiver may stay with your child in the MRI room, provided they follow the rules and special precautions.

    • If you wish to accompany your child into the MRI room, you will need to fill out a questionnaire. It asks about your medical history and helps the MRI department ensure your safety. It is very important that this questionnaire is filled in accurately.
    • The magnet used in MRI scans may affect some medical devices that have been implanted in the body (e.g. older-style pacemakers, implanted defibrillators, various nerve stimulators, infusion pumps and embolisation coils).
    • The following items are affected by the magnet and are not allowed into the scanning room for safety reasons: watches, pens, keys, jewellery, hair pins, safety pins, mobile phones, credit cards, pagers, radios and CD players.

    Before your child has the scan, they must remove all piercings and other jewellery. This is because the metal in the piercing may affect the quality of the scan and can be attracted to the strong magnets used in the machine.

    Some children need to have a contrast injection before having an MRI scan. Contrast shows blood vessels more clearly and gives information about the blood supply and health of an organ in the body.

    Contrast is a clear fluid and is given through a small IV (intravenous, or a drip) line, which is inserted into a vein. If your child is already in hospital and already has a drip in place, staff can usually use this.

    If your child needs to have an IV line inserted, an anaesthetic cream can be used to reduce the discomfort of the IV needle. The cream takes at least 30 minutes to take effect.

    During the scan

    An MRI scan is not painful. The MRI machine does make some loud knocking noises, and it is generally only these noises that children are aware of during the scan. Your child can wear headphones to muffle the loud knocking noise of the machine.

    The MRI scanner is like a big square box with a tunnel through the middle. During an MRI scan, your child will have to lie very still in the tunnel. Your child will lie on a narrow table, which slides into the tunnel. They will usually be on their back.

    • While they are in the tunnel, they can see what is happening outside the tunnel by looking in mirrors that are positioned to show around the room. They can also talk to the MRI technologist through a microphone.
    • Foam cushions and soft straps are used to help your child keep still. A soft flexible wrap goes over their stomach and records the radio waves for the pictures.
    • Usually your child will be scanned in their normal clothes; however, sometimes it is necessary for them to change into a gown or other hospital clothes.
    • The MRI scan can be long and boring for your child (usually it will take around 30 minutes, depending on what parts of the body are being examined). Your child can have their favourite music, movie or TV show streamed into the MRI room to help pass the time. You can bring these preloaded on a smartphone, tablet, MP3 player or a DVD.

    After the scan

    If your child has not had IV contrast, sedation or general anaesthetic, you will be able to leave straight after the MRI scan.

    If IV contrast was needed, your child will be observed for 10 minutes after the scan. It is very rare for a child to have an allergic reaction to the contrast, but if a reaction does occur staff are well trained to manage any adverse events associated with contrast.

    MRI scans have many pictures with a lot of detail, so they often take a long time for the radiologist (medical imaging specialist) to review and report on. The technologist performing the study will not be able to give you any information about the imaging findings at the time of the examination.

    Clerical staff cannot give out results over the telephone. If you have any questions about the results of your MRI scan, speak to your doctor.

    MRI scan with sedation

    If your child is unable to remain still or they are very anxious or distressed and can't be calmed down, they may need sedation before their scan. See our fact sheet Sedation for procedures.

    Whether or not your child needs sedation depends on their age and individual circumstances. Your child will be assessed to ensure that the sedation is suitable for them.

    You will be given fasting instructions to follow before the scan. After the scan, your child will be required to remain under the care of the department nurse until they have recovered properly. 

    MRI scan with general anaesthetic

    Some MRI scans need to be performed under a general anaesthetic. This is rare, but may be required if your child cannot use sedation.

    Your child will need to fast before the general anaesthetic; you will be given instructions about this.

    After the scan, you will need to wait until your child is fully awake and staff say it is OK to go home. Do not worry if your child feels sick or vomits once or twice after leaving hospital. If your child continues to vomit, please call your child's anaesthetist or your nearest hospital emergency department.

    Key points to remember

    • MRI scans involve more pictures and give greater detail than X-rays or ultrasound scans.
    • An MRI scan does not use radiation and is believed to be safe, even for babies.
    • Contrast injections can make a scan more useful by showing more details. Contrast is given through an IV line directly into a vein.
    • Sometimes, MRI scans need to be performed while your child is under sedation or general anaesthetic.

    For more information

    Common questions our doctors are asked

    My child is very anxious about medical procedures and I am worried she won't stay still for the MRI. What can I do?

    Show her our Be Positive video of a child having an MRI scan at The Royal Children's Hospital (RCH). It will help your child to know what to expect. You can also download our Okee in Medical Imaging app, which includes games and information especially designed to help children feel more comfortable about having medical imaging done at the RCH, and includes fun training on how to keep still. To get some ideas of how to talk to your child about the scan before you come to hospital, see our fact sheet Reducing your child's discomfort during procedures. Children having an MRI at RCH may also be able to experiment with our 'Mock MRI' machine, where they can practice having the scan, so that the real scan is more familiar to them.

    My daughter has a copper intra-uterine device (IUD). Is this safe in an MRI machine?

    Most IUDs are made with copper, which does not distort the MRI images. The IUD will not increase in temperature or dislodge during an MRI scan. It is still important, however, that you inform the MRI team of all jewellery, piercings, devices or prostheses (artificial body parts) on you or your child before entering an MRI room.

    Are there any side effects of contrast?

    In rare cases, contrast can cause reactions in children. About one child in 1000 might get a rash, hives, or an irritated mouth or throat. If this happens, your child might need to stay in the hospital a few hours longer and may need some extra medicine (e.g. antihistamines). Very rarely, your child may have a serious and life-threatening reaction and will need to be admitted to hospital for treatment.

    These are allergic reactions that cannot be predicted unless a previous reaction has been experienced. Staff can safely manage any side effects or reactions that may occur. 


    Developed by The Royal Children's Hospital Medical Imaging department. We acknowledge the input of RCH consumers and carers.

    Reviewed October 2018.

    Kids Health Info is supported by The Royal Children’s Hospital Foundation. To donate, visit www.rchfoundation.org.au.


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Disclaimer
This information is intended to support, not replace, discussion with your doctor or healthcare professionals. The authors of these consumer health information handouts have made a considerable effort to ensure the information is accurate, up to date and easy to understand. The Royal Children's Hospital, Melbourne accepts no responsibility for any inaccuracies, information perceived as misleading, or the success of any treatment regimen detailed in these handouts. Information contained in the handouts is updated regularly and therefore you should always check you are referring to the most recent version of the handout. The onus is on you, the user, to ensure that you have downloaded the most up-to-date version of a consumer health information handout.