Magnetic Resonance Imaging (MRI) is a safe and non-invasive scanning technique. Instead of using X-rays, MRI is based on nuclear magnetic resonance. This means all atoms have nuclei with their own resonant frequency. If you disturb them, they sing like tuning forks.

The different structural components of the brain have atoms with nuclei that have their own unique song. The MRI scan sends a high frequency alternating magnetic field through the brain via electromagnets surrounding the brain, thereby disturbing the various nuclei. The magnetic sensors in the scanner pick up the activity of the nuclei.

A computer then generates a two- or three-dimensional image of the brain. This detailed picture of brain structures (not brain functions) helps physicians locate possible causes of seizures and identify areas that may generate seizures. No X-rays or radioactive materials are used. As such, this procedure is not known to be harmful.

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

Before an MRIExpand Before an MRI Section

During an MRIExpand During an MRI Section

After an MRIExpand After an MRI Section

PersonnelExpand Personnel Section

PaymentExpand Payment Section

EquipmentExpand Equipment Section

Additional Types of MRIs

Functional MRI (fMRI)Expand Functional MRI (fMRI) Section

Magnetic Resonance Spectroscopy (MRS)Expand Magnetic Resonance Spectroscopy (MRS) Section

Open MRIExpand Open MRI Section

Important Considerations

The strong magnetic field used for MRI will pull on any ferromagnetic metal object implanted in the body. If you have ever been a metal worker, you may be required to have your eyes X-rayed before having the MRI scan. Fillings in your teeth, dental braces, and permanent bridges may distort images of the facial area or brain, but will not cause harm to you or the MRI equipment.

Notify the doctor or nurse prior to the examination if you have any of the following metal implants or objects:

• aneurysm clips,
• artificial heart valve,
• bullets,
• cardiac pacemaker,
• ear implants,
• eye/orbital prosthesis,
• hip or knee prosthesis,
• insulin pump implant,
• intracranial bypass graft clips,
• intrauterine device (IUD),
• neurostimulators (vagus nerve stimulation device),
• shrapnel,
• sternal wire,
• sutures, or
• tantalum mesh.

A small number of people have experienced skin irritation, swelling, discomfort or burning/heating sensations at the site of any type of permanent colourings (tattooing, cosmetic applications such as eyeliner, lip-liner, lip colouring, etc.). Certain ferrous pigments used in tattoos and permanent colouring can interact with the electromagnetic fields used in the MRI procedure. Large or very dark tattoos can cause “artefacts” or false shadows to appear on the image. Inform the technologist or doctor of any unusual sensations in area of the tattoo or permanent colouring during the examination.

Patients may not have an MRI scan if they are:

• pregnant (whether suspected or confirmed)
• critically ill (The strong static magnetic field interferes with the proper function of the usual life-support equipment, which may make it difficult or impossible to examine some critically ill patients.
• uncooperative (It is essential that the patient lie still.)

Consider “open” MRI systems for:

• claustrophobic patients
• obese patients who may not fit in the scanner

Click here to learn about other types of diagnostic tests.

Positron Emission Tomography is a scanning technique which detects chemical and physiological changes related to metabolism. This procedure produces three-dimensional images of blood flow, chemical reactions and muscular activity in the body as they occur. It measures the intensity of the use (metabolization) of glucose, oxygen or other substances in the brain.

More active brain areas have increased blood flow and consume more oxygen, thus detecting over- or under- activity in the brain. This allows the neurologist to study the function of the brain. By measuring areas of blood flow and metabolism, the PET scan is used to locate the site from which a seizure originates.

The information provided by a PET scan is valuable in the diagnosis of seizure type and in the evaluation of a potential candidate for surgery. The PET scan tests brain metabolism, chemistry or blood flow by injecting a small amount of radioactive substance into the body. When this substance reaches the brain during the scan, a computer uses the recorded signals to create images of specific brain functions.

A functional image of brain activity is important because functional changes are often present before structural changes in tissues. PET images may therefore demonstrate pathological changes long before they would be evident by other scanning techniques.

The limitations of PET:

• The session cannot last very long because it requires the injection of radioactive material.
• It takes time for active brain cells to absorb the radioactive material takes time to be absorbed. The scan images change too slowly to capture fast-changing brain events.

Before a PET Scan

• Do not eat or drink anything four to six hours prior to the exam.
• Wear comfortable clothing.
• Take all prescribed medication(s) as usual unless instructed otherwise by the physician.

During a PET Scan

• Before the scan, the technologist will inject you with a small amount of radioactive tracer. The tracer is a compound (such as sugar) “labelled” with a short-lived radioisotope.
• Following the injection, you will be asked to rest for approximately 30 to 45 minutes while the substance reaches your brain.
• You will be asked to lie on a scanner table. Be sure to lie completely still.
• The scanner table will slowly pass through the PET scanner. Your head will be inside the large, doughnut-shaped machine. The scanner detects the radioactive material to produce a computer image of your brain.
• Scanning time is approximately one to two hours.

After a PET Scan

• There are no after effects from the injection or the PET imaging.
• You can resume normal activity immediately after the PET scan is completed.
• The PET scan will be reviewed by a radiologist or nuclear medicine technologist who will report to your physician. Your physician will then make a follow-up appointment to discuss the results with you.

Personnel

• Nuclear Medicine Technologists
  • operate cameras, which detect and map the radioactive tracer in the patient’s body to create an image on the computer monitor
  • explain test procedures to patients
  • prepare the radiopharmaceutical and administer it orally or through injection.
• Doctors
  • interpret the results.

Important Considerations

Pregnant women should not undergo a PET scan because of the radioactive isotopes used. Inform your doctor if you are pregnant or suspect you may be pregnant.

Availability

Clarke Institute of Psychiatry, Toronto, Ontario
416-535-8501
Research grants to the institute cover the cost of the test.

McMaster-Chedoke Hospital, Hamilton, Ontario
905-521-2100
The hospital covers the cost of the test.

Montreal Neurological Institute and Hospital, Montreal, Quebec
514-398-5358
You must pay $700 for the test, but the Ontario Health Insurance Plan (OHIP) will fully reimburse you.

University of British Columbia, Vancouver, British Columbia
604-822-2211 (general directory)

Epilepsy Foundation (of America) – for locations in the United States
301-459-3700
www.efa.org
You must pay approximately US$1700 for the test, which insurance does not cover.

Click here to learn about other types of diagnostic tests.

The CAT scan, also known as CT (Computed Tomography) imaging, is a safe and non-invasive procedure which uses low radiation X-rays to create a computer-generated, three-dimensional image of the brain. It provides detailed information about the structure of the brain.

The CT scan uses a narrow beam of X-rays, which pass through the head and hit a detector on the opposite side. The beam moves around the head and the detector moves with it. Since different brain tissues have different densities, each will block the X rays from reaching the detector to different degrees. These may reveal abnormalities (blood clots, cysts, tumours, scar tissue, etc.) in the skull or brain which may be related to seizures.

This allows physicians to examine this structure, section by section, as the test is being conducted. The CAT scan helps point to where a person’s seizures originate. The CT scan only shows what the brain looks like, not how it works. The scanning period is brief, safe and painless.

Before a CAT Scan

• Dress in comfortable, loose-fitting clothing.
• Remove any metal objects such as jewellery, belts, hairpins, hearing aids, glasses or dentures. These objects  may degrade the clarity of the images.
• If a contrast medium is going to be used, do not eat or drink anything four to eight hours before the test.
  • A contrast medium is a dye that may be given to you orally or injected into your hand or arm. This fluid goes up to the brain and makes the scan easier to read.
  • Some people are allergic to particular contrast mediums. It is important to inform your doctor if you have any allergies, especially to iodine.
    • You should also inform the doctor if you have diabetes, asthma, a heart condition, kidney problems, or thyroid condition. These conditions may indicate a higher risk of iodine reactions.
  • Inform the technician if you feel any itching or shortness of breath after the administration of the contrast medium.
    • After the injection you may feel flushed, have a metallic taste in your mouth, or feel nauseated.
    • Another mild reaction that can occur following the administration of iodine is itching over various parts of the body. This lasts from several minutes to several hours and is usually treated with medication.
    • More serious but less common reactions may include shortness of breath, swelling of the throat or other parts of the body. These reactions should be treated immediately.
  • A CAT scan still provides valuable information without administering a contrast agent. If you are at risk of reaction to the contrast agent, the physician may decide not to administer it during a CAT scan.

During a CAT Scan

• After the administration of the contrast agent, you will be asked to lie down on a scanning table.
• The technician will move to another room and then proceed to move your body into the scanner machine.
• A series of X-rays will be taken by a camera, which will rotate around your head.
• It is important that you lie completely still until the entire examination is complete.
  • Any movement will blur the image.
  • You may be asked to hold your breath during the scanning procedure to help to eliminate blurring of the images caused by the movements of breathing.
• During the examination, you will hear some noise from the machine and the CT table may move slightly. This will not cause any discomfort.
• If you have any questions or concerns throughout the examination, you can speak with the technologist via intercom.
• You cannot have anyone in the room with you during the scanning process. Because the CT scanner uses X-rays, only the person being imaged should be in the CT scanner room during the procedure.
• A scan can be obtained in about 15 to 20 minutes.

After a CAT Scan

• You can return to your usual daily activities and resume your regular diet immediately after the scan unless instructed otherwise by the doctor.
• If you were given an injection and the injection site remains sore, you are encouraged to call your physician.
• You must have someone drive you home from the test site, as the effects of the sedative may not have worn off yet.
• A radiologist will interpret the images and send them to your doctor who will review the results with you at a follow-up appointment. Additional tests or a treatment plan will be designed accordingly.

Important Considerations

• If you have allergies or have experienced discomfort because of any contrast agent previously, inform the technologist and the doctor before the examination.
• If you are nursing an infant, you should wait 24 hours after receiving the CT contrast injection before breastfeeding again.
• If you are pregnant, you should not have a CT examination. It is extremely important that you inform your doctor if you are pregnant or think you are pregnant before proceeding with the examination.

Personnel

• Radiologists
  • interpret the CT images
  • send a report to the referring physician
  • administer or observe the contrast injection
• CT technologists
  • operate computerized tomography scanner to produce cross sectional views of the body section being scanned
  • perform the examination under the supervision of the radiologist
  • may also administer the contrast injection

Payment

The CAT Scan is covered by the Ontario Health Insurance Plan (OHIP).

Click here to learn about other types of diagnostic tests.

Neuropsychological testing (also known as neuropsychometric testing) assesses a variety of brain functions including:

• memory,
• reading,
• comprehension,
• judgment,
• motor abilities,
• spatial perception and
• ability to process and interpret information.

The tests quantitatively measure these functions to demonstrate possible abnormalities of the brain. This may help to identify the type of epilepsy an individual has and locate the origin of the patient’s seizures.

Individuals with epilepsy occasionally report difficulties with memory, concentration or other cognitive areas. Neuropsychological tests assess these abilities and provide information about a person’s strengths and weaknesses. This offers doctors some insight into the cause and severity of seizures. They may also aid in the patient’s evaluation for surgical treatment.

Before the Exam

• Prepare a snack to bring to the test as the procedures are lengthy.
• If you wear eyeglasses or hearing aids, please continue to do so on the day of the test.

During the Exam

• The neuropsychologist will ask you to do the following tasks one at a time:
  • answer questions,
  • solve puzzles,
  • work with objects,
  • remember words and sounds.
• The tests usually last seven to eight hours.

Commonly used tests include:

• Wechsler Intelligence Scale for Children (WISC)
• Bender Visual-Motor Gestalt Test
  • The visual test involves copying a bunch of abstract designs to identify organic brain damage.
  • The motor test may involve sorting cards into different categories that the patient needs to determine based on the feedback of the clinician.
• Wechsler Adult Intelligence Scale (WAIS)
  • This test helps test memory and retention.
• Minnesota Multiphasic Personality Inventory
• Rorschach Ink Blot Test
• Thematic Apperception Test (TAT)
• Sentence completion
• Goodenough draw-a-person test (often for children under 12)
• Stanford-Binet Intelligence Scale

After the Exam

• A neuropsychologist will interpret your test results and send the report to your physician.
• The physician will then make an appointment with you to discuss the results.

Personnel

• Neuropsychologist
  • administers the test and interprets the results.
• Psychology Assistant
  • assists the neuropsychologist (HSC)
• Doctor
  • receives report from neuropsychologist
  • discusses the results with the patient

Payment

This test is covered by the Ontario Health Insurance Plan (OHIP).

Click here to learn about other types of diagnostic tests.