What Is Magnetic Resonance Imaging (MRI)?
Magnetic resonance imaging uses a powerful magnet and radio waves to make pictures of the inside of the body. It can pick up a lot of detail in the different tissues to build two- or three-dimensional images.
You might also hear your doctors refer to this procedure as an MRI scan or MRI.
What Body Parts Are Involved?
An MRI scan can be used to evaluate any part of the body.
Why Does My Child Need an MRI Scan?
An MRI scan is often used to find and diagnose internal injuries and conditions. It is especially good for looking at soft tissue such as organs, muscle, cartilage, ligaments, and tendons in many parts of the body. MRI scans allow doctors to see whether certain tissue in your child's body is healthy or unhealthy.
How Does an MRI Work?
An MRI scan can even show flowing blood in just about any part of the body. Unlike other methods of imaging, MRI can often achieve this without the need for an injection of contrast dye.
Doctors may also use MRI to monitor effects of medications and treatments inside your child's body. If your child is being evaluated for a transplant, he or she may have an MRI. This is part of a thorough physical examination conducted by transplant specialists to determine whether transplantation would be a safe and beneficial option for your child.
Can Anyone Have an MRI Scan?
Because of the magnetic force involved, people who have any of the following in their bodies may not be able to have an MRI exam:
- Pacemaker
- Neurostimulator
- Ear implant
- Metal clips in the eyes
- Implanted port or medication device, such as an insulin pump
- Intrauterine device (IUD)
- Metal plate, pins, screws, or surgical staples
- Metal clips from aneurysm repair
- Metal joint replacements or heart valve replacements
- Retained bullets
- Any other large metal objects implanted in the body (tooth fillings and braces are usually not a problem)
People whose occupations involve work with metal filings or particles should tell their doctors before having an MRI exam.
Most doctors also prefer not to perform MRI scans on pregnant women, because there is not enough research to show that it is safe for the developing fetus.
MRI Procedure: What to Expect
Preparing for an MRI
If your child's physician decides to use contrast dye to enhance the MRI pictures, your child may need to be NPO (fasting, nothing by mouth) for several hours prior to the procedure. You will receive MRI preparation instructions about this from your child's physician or another healthcare professional.
Children may receive a mild sedative to make them feel more comfortable, and to help them to remain still and quiet during the test. In this case, your child also would need to fast for several hours beforehand. If your child has not been prescribed a sedative, he or she may eat or drink normally, unless the doctor or technician tells you otherwise.
At the hospital or MRI center, you will be asked about your child's:
- Medical history
- Pregnancy or possible pregnancy, if female
- Allergies – especially any previous reaction to contrast dye, as well as allergies to iodine or seafood
- Prior head surgery
An X-ray may be taken beforehand if there is doubt as to whether there are metal objects in your child's body.
Any metal jewelry, hair clips, or barrettes your child is wearing will have to be taken off before the test. Your child should also avoid using hair gel, spray, lotions, powders, and cosmetics on that day.
Your child may wear street clothes or change into a hospital gown. If your child will be wearing his or her clothes, they should be loose-fitting and comfortable, with all objects removed from the pockets.
During the MRI procedure
The MRI scanner is located in a large room. Your child will lie on a narrow table that slides into the hollow tube-shaped scanner.
You may be able to stay with your child in the MRI room until he or she becomes sleepy, but are usually asked to wait in another area during the procedure to avoid exposure to unnecessary radiation.
The MRI physician and staff will be in an adjacent room where the equipment controls are located. However, they will be able to see your child through a large window and will be monitoring him or her constantly during the procedure. If your child is not sedated, he or she will be given a call bell device. Your child can use this call bell to let the staff know if he or she needs anything during the procedure.
The MRI scanning machine makes loud banging or knocking noises when adjustments are being made. Your child will wear a set of headphones to help protect his or her 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.
Once the procedure begins, your child will need to remain very still at all times so that movement will not adversely affect the quality of the images. At intervals, your child will be instructed to hold his or her breath, if possible, for a few seconds. Your child will then be told when to breathe. Your child should not have to hold his or her breath for longer than a few seconds, so this should not be uncomfortable.
The procedure is not painful at all, but your child may feel claustrophobic or nervous about having to stay still. Young children who cannot remain still for the procedure will be given medication to help them relax or sleep during the MRI scan.
If the MRI scan is being done "with and without contrast," your child will receive contrast medication through an IV about halfway through the procedure. He or she may feel a warm or flushed sensation just after the dye goes into the vein – this is a normal sensation and it will go away shortly.
Once the procedure is finished, the table will slide out of the scanner. If your child received medication for relaxation or sleep, he or she will be monitored until the medication wears off and he or she is awake again. If an IV was inserted, it will be taken out after the procedure is over and your child is awake.
The test normally takes between 30 and 90 minutes.
After the MRI procedure
You will be asked to wait until MRI images are examined to determine if more images are needed. If so, more images will be taken at that time.
Without sedation, your child should be able to resume normal activities immediately after the scans are finished, unless your child's physician instructs you otherwise. With sedation, your child may feel groggy, tired, or sleepy for a period of several hours after the procedure. However, the sedation effects should disappear within a day or so.
If your child received contrast dye, have him or her drink extra fluids to flush it out more quickly. Unless your child is already an inpatient at the hospital for another reason, there is no hospital stay involved.
Are There Complications Associated with an MRI Scan?
Very rarely, people have allergic reactions to the contrast dye. Doctors and technicians will know what to do in the event your child does have this type of reaction.
MRI Results
After the exam, an MRI radiologist will analyze the images and send a report to your child's doctor. Your child's doctor will discuss the results and any further action, tests, or treatment that may be necessary with you. Depending on the results of the MRI scan, additional tests or procedures may be scheduled to gather further diagnostic information.
My Child is Not Feeling Well After an MRI. Should I Call the Doctor?
Be sure to contact your child's doctor if your child experiences:
- Any allergic or abnormal symptoms after an exam in which he or she was injected with contrasting dye
- Worsening of any of the symptoms that prompted the MRI exam
Get the MRI Scan Patient Procedure.
