MRI (magnetic resonance imaging) scan factsheet

Introduction

Magnetic resonance imaging (MRI) is a scan that uses powerful magnets and sound waves to take detailed pictures inside the body.

MRI scans look at soft tissues such as the:

brain
joints
heart
blood vessels
other internal organs.

They are used to check for things like:

cancer and tumours
disease
injuries
organ damage.

MRI scans do not hurt, but can be uncomfortable. This is because the MRI machine tunnel is small, and your child must lie still for a long time.

Before the scan

You will get instructions from the hospital or your child's doctor about:

what to bring
where to go
how to prepare.

These instructions may be different depending on the body part being scanned. Some MRI scans do not need any preparation.

Tell your child’s treatment team if your child has:

allergies
asthma
kidney problems
recent surgery
claustrophobia - fear of small spaces
metal implants or devices in their body.

MRI and metals

The MRI machine uses strong magnets that attract metal. This can be dangerous and affect the scan quality. Your child will change into a hospital gown to make sure they are not wearing any metal.

If you are unsure about metal implants or devices and the MRI, speak to your child’s doctor.

Sedation and fasting

The MRI machine can be scary or uncomfortable because it feels small, and your child must stay still for a long time. Some children may need help to relax, such as:

general anaesthetic - medicine to put your child to sleep during the scan
sedation - medicine to relax your child, but not put them fully to sleep.

If your child has a general anaesthetic or some types of sedation, they will need to stop eating or drinking two hours before the scan.

This is to stop aspiration, which is when food or water is brought up into the lungs during a procedure. Aspiration can be life-threatening.

Children having sedation or general anaesthetic will need an intravenous (IV) cannula placed in their hand or arm to give medicine during the scan.

Contrast

Some children may need to have contrast, a liquid that helps body parts show clearly on the scan. Contrast may be given:

orally as a drink
through an IV cannula.

Contrast can make your child feel unwell, so they must fast before the scan.

Tell your child’s doctor if they have had an allergic reaction to contrast or a previous scan.

During the scan

The MRI machine is a large tunnel with a flat bed. The radiographer, who runs the scan, will stay outside the room but can speak to your child through a microphone.

The machine makes loud tapping and buzzing sounds. Your child will wear headphones or earplugs to protect their ears.

Some MRI machines have a screen so your child can watch a movie during the scan. Ask your child’s treatment team if this is available.

Your child will be given a buzzer to squeeze if they need the scan to stop.

Each scan takes 30 seconds to 7 minutes. The whole scan can take between 20 and 120 minutes.

Generally, the steps of an MRI scan are:

your child will lie on the flat bed of the MRI machine
if your child is sedated or asleep, staff will place them on the bed
a frame may be placed over the part of their body being scanned to help keep it still
the bed slides into the tunnel, and the scan begins.
the machine will make loud tapping and buzzing sounds, and the bed may move slightly
your child may be asked to hold their breath at times
between scans, the radiographer will check on your child and encourage them to stay still
if your child moves, some pictures may need to be taken again.

After the scan

When the scan is finished, your child can go back to normal activities.

If your child had sedation or general anaesthetic, they will go to a recovery area to wake up.

The results will be sent to your child’s doctor within a couple of days. You will need to schedule a follow-up appointment with your child’s doctor to discuss the results.

Management

What to Expect from the MRI Machine

The MRI machine is a large tunnel where your child will lie during the scan. Some children may find it feels small or cramped. It can help to talk to your child about this and practise lying still in a small space, like under a bed or in a play tunnel.

The machine makes loud and unusual noises while it takes pictures. Playing these sounds to your child before the scan can help them feel less scared.

Breath Holding Techniques

Your child will need to hold their breath during parts of the scan. This helps the hospital team take clear pictures. There are two ways to practise breath holds: holding their breath in, and holding it out. Practising at home can make it easier on the day of the scan.

To practice breathing in:

ask your child to take a deep breath in until they can’t breathe in any more
tell them to stop and hold their breath while you count to 10–20 seconds
remind them to keep their mouth, cheeks and tummy still
tell them to let go of the breath they are holding
let them breathe normally before starting another breath in.

To practice breathing out:

ask your child to take a deep breath in
tell them to blow all the air out through their mouth
when they can’t blow any more, tell them to stop
remind them to keep their mouth, cheeks and tummy still
let them breathe normally before starting another breath out.

On the day of the scan, your child may be asked to show how they hold their breath.

They will be told which type of breath hold to do during the scan. Instructions will be given through a speaker in the room, letting your child know when to hold their breath and when to breathe normally.

Supporting your child during the scan

Scans can be stressful for children. You can help by:

explaining why the test is needed and how it works in simple words
bringing comfort items like a blanket, toy, or dummy
asking the treatment team about support from Child Life Therapy services
arriving 30 minutes early if using numbing cream.