What is MRI?
Magnetic resonance imaging (MRI) is a way of taking pictures of the inside of the body without X-rays. MRI uses a strong magnet and radio signals to take pictures of the inside of the body.
Some MRI scans provide more information when they are done with a liquid called contrast. This clear, colourless fluid is put into the vein in the wrist or arm with a small tube and needle through an intravenous line (IV). If needed, the IV will be inserted before the MRI scan.
Contrast is normally very safe, but it may produce a reaction in very rare cases. The team will watch your child very closely during and after the MRI to see if your child has a reaction.
How long does an MRI take?
A number of short scans make up a complete MRI study. Each scan takes from one to 10 minutes. The total time for a complete MRI study depends on the area of the body that is being scanned, but it may take up to one to two hours.
Tell the MRI team about any metal in your child's body
Because MRI involves a strong magnetic field, certain metal implants could injure your child. Tell the MRI team if your child has had any surgeries, procedures, implants, or injuries that involved metal, such as metal rods, plates, screws, braces, clips, or body piercings.
Your child will have to empty their pockets completely of everything, including coins, keys, pens, cell phones, wallets, and bank cards. They will also have to take off their watch. Your child cannot wear any makeup or jewelry.
If your child does have any implants, please give the MRI team information about the type of device and the manufacturer. In some cases, your child may need an X-ray to confirm that it is safe for them to have an MRI.
Is there any preparation for MRI?
If your child is able to lie perfectly still for an hour, then no special preparation is usually needed for the scans. However, many children need medicine to help them sleep, so they will lie still for the scan. This medicine may be a type of sedation or a general anesthetic. The type of sedation or anesthetic your child needs depends on their age and medical condition.
Before having any sedation or general anesthetic, your child will need to have an empty stomach. The treatment team will tell you when your child needs to stop eating and drinking before the MRI.
What should I tell my child?
Tell your child exactly what will happen during the MRI scan. Explain what they will see, hear and feel. Remember, MRI scans do not hurt. Visit the SickKids MRI page for more information, including videos your child can watch to better understand what to expect on the day of their scan.
What to do if you need to cancel your child's appointment
If you have to cancel your child's MRI appointment or if you have any questions, please call the department as soon as possible.
If your child becomes ill before the MRI appointment
For their own safety, it is important that your child is healthy on the day of the MRI. If your child is unwell prior to the MRI appointment, please call the department as soon as possible. It may need to be rebooked.
If you are late for your child's appointment, we may have to delay or cancel your appointment.
Who performs an MRI?
Several people may be involved in the procedure: a technologist, a nurse, a radiologist and—if necessary—an anesthesiologist.
- A medical radiation technologist (MRT) will do the MRI scans.
- A nurse will prepare your child for the scans. If your child is having sedation, the nurse will give the sedation. If your child is having a general anesthetic, the nurse will assist the anesthesiologist.
- A radiologist will check and interpret each MRI scan to make sure that the study is complete.
- The anesthesiologist is the health-care provider who gives the general anesthetic.
What happens during the MRI?
Your child will change into a hospital gown and lie on a bed. The technologist will place them in the correct position for the MRI scan. The MRI scanner is a large machine with a wide tunnel in the centre.
When everything is ready, the bed will be moved into the tunnel. Most of your child's body will be inside the tunnel.
Your child must lie completely still for the whole time of each MRI scan.
The MRI machine will scan your child’s body in "slices” to produce cross-sectional images. Each image shows a different slice or level of the body part being imaged. The scanner makes a loud knocking or drumming sound during scanning. Everyone staying in the room will wear ear plugs or headphones to protect their hearing.
In some scanners, there is an entertainment system so your child will be able to watch a movie while having the scan.
The technologist will talk to your child through a speaker. When the MRI scan is complete, the technologist will help your child off the table.
If your child does not need to be asleep during the study, you will be able to stay in the room with your child if you wish. If you wish to stay in the room, you will also need to be screened for metal implants.
What happens after the MRI?
If your child has had sedation or general anesthetic, you must stay until they are awake. The MRI nurse will let you know when you can leave. The radiologist will review the MRI study, and a report will be sent to your child’s health-care provider. Their health-care provider will discuss the results of the study with you at a follow-up appointment.
MRI without sedation or general anesthesia
The WAGS program (Wonderful Alternatives to General Anesthesia & Sedation) provides techniques for alleviating anxiety and reducing the need for general anesthesia in paediatric diagnostic imaging, particularly in MRI. To learn more about the WAGS program at SickKids, please visit https://www.sickkids.ca/en/care-services/clinical-departments/diagnostic-interventional-radiology/wags/.
