Epilepsy Ontario :: MRI (Parents)

Magnetic Resonance Imaging (MRI)

Magnetic Resonance Imaging (MRI) is a safe and non-invasive scanning technique that uses a magnetic field, radio waves, and a computer to produce two or three dimensional images of the brain. This detailed picture of brain structures helps physicians locate possible causes of seizures and identify areas that may generate seizures. No x-rays or radioactive material are used, therefore this procedure is not known to be harmful.

An MRI offers doctors the best chance of finding the source of seizures. Because epilepsy can arise from scar tissue in the brain, an MRI can show scar tissue and allow doctors to determine the nature of it. The images produced from the MRI are extremely precise. The information provided my MRI is valuable in the diagnosis and treatment of individuals with epilepsy and to determine whether surgery would be beneficial.

Before an MRI

Prior to the test, your child should eat and drink normally unless instructed otherwise by the doctor.
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Infants and children who will be sedated should not eat or drink for approximately 4 hours prior to the exam.
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All prescribed medication(s) should be taken as usual.
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To gain the most co-operation from your child, it is best if your child is tired or hungry. Therefore, keep your child up late the night before and don't let them nap prior to the examination. Bring a bottle to feed your infant upon arrival of the examination.
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It will be more easier for your child to relax during the exam if you avoid giving them too much liquid or caffeine drinks.
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Dress your child in loose, comfortable clothing.
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All jewellery, hairpins, glasses, hearing aids, certain dental work or any metal objects should be removed before the examination. Metals can cause a bright or blank spot on the images.
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If your child is claustrophobic (fears closed-in spaces), you should inform the doctor before taking the test.
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Some children who are not usually claustrophobic may become anxious inside an MRI machine. In this case, you should talk to the doctor and ask about appropriate medication.
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During an MRI

The technologist will ask you about your child's medical history.
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The technologist will help your child to will lie down on a cushioned table.
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When your child is comfortably positioned for the exam, the table will slide towards the machine so his/her head is inside its circular opening. It is important for your child to lie flat and still as s/he moves through a narrow cylinder.
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The technologist will step to the control area, and remain in constant contact with your child. Your child will be able to speak to the technologist through an intercom. The technologist will talk with your child frequently during the scan, explaining the procedure each step of the way.
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You may stay with your child during the procedure because there are no known risks to those in the room with the machine.
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To help your child relax and to reassure him/her that s/he is not alone, you may want to give gentle foot and leg massages.
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Your child may take a nap during the procedure, if s/he wishes.
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The technologist will remind him/her to stay still as the images are taken. Any movement during this time will blur the picture.
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Your child may hear thumping sounds from the machine and may feel a slight vibration which is normal. It is important to inform your child of these noises so s/he will not panic but remain still during the examination.
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In some cases, the physician may request an Magnetic Resonance Angiography (MRA) in addition to your MRI exam. This exam will provide an analysis of your child's vascular system and major blood vessels. Usually, the MRI and MRA are completed in the same visit.
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The MRI procedure usually takes 30 to 90 minutes.
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After an MRI

There are no harmful side effects after the examination and your child can resume normal activities and diet immediately after the scan.
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If a sedative is administered, your child will be monitored until the effects of the sedative subside.
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The MRI scan will be reviewed by the radiologist who will send a report to your physician.
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After the physician receives the results of the test, s/he will confirm a diagnosis or prescribe further tests and treatments.
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Personnel

MRI Technologist

operates the MRI machines using giant magnets and radio waves to create an image;
takes patients' medical histories;
prepares patient for the MRI examination;
prepares data for doctors to interpret.
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Radiologist

interprets images and sends report to the referring physician.
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Doctor

interprets the results.
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Payment

An MRI examination is covered by the Ontario Health Insurance Plan (OHIP).
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Equipment

The MRI machine is a cylindrical magnet in which the patient must lie still. S/he may feel claustrophobic. Some newer MRI systems are wider and shorter, and do not fully enclose the patient; some are open on all sides. However, the image quality may vary.
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Additional Types of MRIs

A functional MRI (fMRI) is a non-invasive technique that provides both an anatomical and functional view of the brain. Similar to the MRI, fMRI uses magnetic fields instead of x-rays to produce detailed pictures of the brain. This technique allows us to localize specific areas of brain function by imaging patients while they perform specific tasks. Therefore, functional MRI can identify regions of the brain that are active during cognitive, sensory, and other tasks by detecting changes in blood flow to particular areas of the brain. This information is often very useful to the neurosurgeon; it helps physicians identify the exact location of the source of the seizures.

Magnetic Resonance Spectroscopy (MRS) gives information about the chemical and physiological information about certain structures in the brain.
The "open" MRI is a new design with an extra large opening. This allows more airflow and an open view around you during the examination. This open design is good for those who are claustrophobic because it allows you to feel less enclosed and confined, thus, minimizing anxiety. Because of the open view, this system provides enough room to image patients weighing more than 200 kilograms (500 pounds). In addition, the "open" MRI allows the patient to be accompanied throughout the examination by a family or staff member. Having someone in the room can be very comforting, especially for infants and frightened children.
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Important Considerations

Because the strong magnetic field used for MRI will pull on any ferromagnetic metal object implanted in the body, you should notify the doctor or nurse prior to the examination if your child has any of the following metal implants or objects:
Fillings in teeth, dental braces, and permanent bridges may distort images of the facial area or brain, but will not cause harm to your child or the MRI equipment.
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Your child should not have an MRI scan if she is, or may be, pregnant.
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The strong static magnetic field, which interferes with the proper function of the usual life-support equipment, and the small bone of the magnets make it difficult or impossible to examine some critically ill patients.
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An MRI scan cannot be performed on unco-operative patients because it is essential that the patient lie still.
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An MRI scan cannot be carried out on claustrophobic patients. However, there are MRI systems with a more open design for patients who are claustrophobic. In this system, the individual can see all around them throughout the exam. These scanners increase comfort levels of patients, but are subject to more background interference in the images produced.
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A small number of people have experienced skin irritation, swelling, or heating sensations at the site of any type of permanent colourings (tattooing, cosmetic applications such as eyeliner, lip-liner, lip colouring, etc.). The reason for this is that certain ferrous pigments used in tattoos and permanent colouring can interact with the electromagnetic fields used in the MRI procedure. The patient might feel some discomfort or a burning feeling on their skin. Large or very dark tattoos can cause "artifacts" or false shadows to appear on the image. Therefore the patient should inform the technologist, or doctor of any unusual sensations in area of the tattoo or permanent colouring during the examination.
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Individuals who are obese may be to big to be scanned.