Magnetic resonance imaging (MRI), nuclear magnetic resonance imaging (NMRI), or magnetic resonance tomography (MRT) is a non-invasive medical imaging technique that uses a magnetic field and pulses of radio wave energy to make images of the anatomy and the physiological processes of the body in both health and disease.
In many cases, MRI gives different information about structures in the body than can be seen with an X-ray, ultrasound, or computed tomography (CT) scan. MRI also may show problems that cannot be seen with other imaging methods.
For an MRI test, the area of the body being studied is placed inside a special machine that contains a strong magnet. Pictures from an MRI scan are digital images that can be saved and stored on a computer for more study.
The images can also be reviewed remotely, such as in a clinic or an operating room. In some cases, contrast material may be used during the MRI scan to show certain structures more clearly.
The following video demonstrates a patient undergoing Magnetic Resonance Imaging (MRI) as a part of cancer treatment. This video was designed to educate parents and caregivers by showing an actual MRI.
Why an MRI is Done
An MRI may be done to diagnose cancer; an MRI can help find tumours in the brain, spinal cord, head, neck, bones, breast, muscles or other soft tissue.
An MRI can be used to determine the stage (how far the cancer has spread and if it is present in other organs and tissues), and can also help plan cancer treatment.
Performing the Procedure
The patient will lie still on the table inside the MRI machine while it takes pictures. There will be a rhythmic knocking sound during the scan, like a drumbeat.
Some children are frightened by the sound. Sometimes parents are unable to stay in the same room during the test, however, a microphone and a mirror allow the parents and staff to always hear, see and talk to the patient.
Prior to the test, you child will need to remove any metal jewelry, belts, etc. because the machine contains a very strong magnet that attracts metal.
Your child will need to lie still during this test and it may take from 30 minutes to 2 hours to take the pictures; if anaesthetic is necessary the test may take longer (2–3 hours).
Straps and pillows may be used to help your child stay in the correct position and hold still during the exam. Surface coils may be placed around or near the area being scanned. These coils help improve the image quality of superficial structures, such as the neck, shoulder, knee or breast.
Potential Side Effects
MRI uses no radiation and has no known harmful effects.
- Some individuals may have a mild reaction to the contrast medium;
- Symptoms may include nausea, pain at the injection site and a headache;
- There are some risks associated with sedation or general anaesthetic.
Special Considerations for Children
Being prepared for a test or procedure can reduce anxiety, increase cooperation and help your child develop coping skills. Parents or caregivers can help prepare children by explaining to them what will happen, including what they will see, feel and hear during the test.
The child needs to lie still on the table during the MRI. Foam cushions and Velcro straps may be placed on the forehead and arms to help the child remain still.
Children under 8 years of age are usually given general anaesthesia to help them relax and lie still for the whole test. For young children, it may be helpful to wake them early or keep them from napping on the day of the scan, so they fall asleep more easily when sedation is given.
If sedation or a general anaesthetic is being used, your child may not be allowed to eat or drink several hours before the test; they may have an IV inserted and may be placed on a heart monitor
If a contrast medium is used and given intravenously (into a vein), the child will feel a slight pin prick when the needle is inserted.
Some hospitals will allow you to be in the room with your child while they are undergoing an MRI, provided you follow the rules and special precautions.
Lying still can be stressful for children, especially the younger ones, and some children may be frightened by the knocking sound.
An MRI can be explained as a camera that looks like a tunnel. Tell your child that the machine is noisy but does not hurt. Older children can bring in their favourite music to listen to during the scan. Younger children can take a cuddly toy or blanket into the MRI machine with them, as long as it has no metal parts.
Your child’s medical team should inform you of any special preparations that may be required before an MRI – if not, ask them!