Magnetic resonance imaging (MRI) is a procedure that uses a large magnet, radio waves, and a computer to create detailed images of organs and tissues in the body. It's used to diagnose problems in many areas of the body.

There are different types of MRI machines. Some look like narrow tunnels. Others are more open and may be a choice for children who can't handle small, confined spaces. The machine creates a strong magnetic field, which works with radio waves to change the position of the body's hydrogen atoms. As they go back into correct position, they send out signals. A computer receives the signals and converts them into images of the body. This image appears on a computer screen.

A child may need an MRI for many reasons, such as to find:

• Organ problems.
• Bone problems.
• Injuries.
• Growths.
• Infection.

Your child's doctor may have other reasons to order an MRI.

Risks include:

• Problems with undetected metal implants or foreign bodies.
• A reaction to sedative or anesthesia, such as headaches, shivering, or vomiting.
• An allergic reaction to contrast dye, such as hives, itching, or wheezing.
• Bruising at the I.V. (intravenous) line site.
• In very rare cases, an illness called nephrogenic systemic fibrosis that has been linked to the I.V. contrast dye used in MRIs in people with pre-existing kidney failure.

You can help your child by preparing them in advance. Many hospitals have people trained in helping children cope with their medical care or hospital experience. These people are often called child life specialists. Check with your child's doctor to see if child life programs or other similar services are available for your child. You can also do certain things to help your child get ready for a test. How best to do this depends on your child's needs. Start with the tips below:

• Use short and simple terms to describe the test to your child and why it's being done. Younger children tend to have a short attention span, so do this shortly before the test. Older children can be given more time to understand the test in advance.
• Tell your child what to expect in the hospital or outpatient facility during the test. For instance, you could talk about who will be giving your child the test and what the MRI room will look like.
• Make sure your child understands which body parts will be evaluated in the test.
• As best you can, describe how the test will feel. The MRI scanner causes no pain. If your child is awake during the test, they may feel some mild pain or pressure when the needle is inserted if I.V. contrast is needed. Reassure your child that this discomfort won't last long. If awake, your child may become uncomfortable from lying still.
• Allow your child to ask questions and answer these questions truthfully. Your child may feel nervous or afraid. They may even cry. Let your child know that you'll be nearby during the test.
• Use play when telling your child about the test, if appropriate. With younger children, this can include role-playing with a child's favorite toy or object. With older children, it may help to read books or show pictures of what happens during the test.

Also:

• Follow all instructions from the doctor to prepare your child for the test.
• Stop giving your child certain medicines or supplements before the test, if directed.
• Follow any directions your child is given for not eating or drinking before the test, if contrast dye will be used during the test.
• Before the procedure, you'll be given a questionnaire about metal or electronic devices. Remove any metal objects your child may be wearing, such as jewelry, hair clips, or clothing with zippers. These things may interfere with the MRI scanner's magnetic field.
• Dress your child in comfortable clothes on the day of the test.

Tell the doctor if your child:

• Has an implanted device or metal clips or pins in their body.
• Has ever had an imaging test such as an MRI or CT with contrast dye.
• Is allergic to contrast dye or any medicines.
• Has a serious health problem (this includes diabetes or kidney disease).
• Is pregnant or may be pregnant, or is breastfeeding.

The test takes about 30 to 60 minutes. Some may take longer. You may be able to stay with your child in the MRI room. Or you may be asked to wait in another area during the test.

An MRI scan is done by a radiology technologist. A radiologist is on call in case of problems. This is a doctor trained to use MRI or other imaging methods to test or treat patients.

During the procedure:

• Your child lies on a narrow table that slides into the MRI scanner.
• Your child will need to lie still during the scan. Movement affects the quality of the results and can even require a repeat scan. Your child may be restrained or given medicine to relax (sedative) or sleep (anesthesia). The sedative is taken by mouth or given through an I.V. line. A nurse helps with this process.
• The technologist is nearby and views your child through a window. If your child is awake, they can speak to and hear the technologist through a speaker inside the scanner.
• The MRI scanning machine makes loud banging or knocking noises. Your child will wear a set of headphones to help protect their ears from the noise of the scanner and to hear instructions from the MRI staff. Music may be played in the headphones when instructions are not being given.
• Contrast dye may be used to improve image results. Your child is given contrast dye in an I.V. line. Your child may feel a warm sensation when it is injected and may have a metallic taste for a short time.
• The staff may place a coil over the body part being tested. The coil sends and receives radio waves and also helps improve image results.
• Once the scan begins, your child will need to lie very still at all times. Movement will affect the quality of the images. At times, your child will be told to hold their breath for a few seconds.

Once the test is finished, the table will slide out of the scanner. If your child received medicine to relax or sleep, they will be watched until the medicine wears off and they are awake again. If an I.V. was inserted, it will be taken out after the test is over and your child is awake.

If no sedation was used, your child can go back to normal activities and diet right away, unless the doctor says otherwise. Contrast dye should pass through your child's body in about 24 hours. Your child may need to drink more water during this time.

If your child had sedation, they may feel sleepy for a while. This should go away in a few hours or a day.

Your child's doctor will talk with you about the results of the MRI, and let you know if other tests are needed.

Before you agree to the test or the procedure for your child, make sure you know:

• The name of the test or procedure.
• The reason your child is having the test or procedure.
• What results to expect and what they mean.
• The risks and benefits of the test or procedure.
• When and where your child is to have the test or procedure.
• Who will do the procedure and what that person's qualifications are.
• What would happen if your child did not have the test or procedure.
• Any alternative tests or procedures to think about.
• When and how will you get the results
• Who to call after the test or procedure if you have questions or your child has problems.
• How much will you have to pay for the test or procedure.