What is magnetic resonance imaging (MRI)?

Magnetic resonance imaging (MRI) is a diagnostic procedure that uses a combination of a large magnet, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.

How does an MRI scan work?

The MRI machine is a large, cylindrical (tube-shaped) machine that creates a strong magnetic field around the patient. This magnetic field, along with a radiofrequency, alters the hydrogen atoms' natural alignment in the body. Computers are then used to form two-dimensional (2D) images of a body structure or organ based on the activity of the hydrogen atoms. Cross-sectional views can be obtained to reveal further details. MRI does not use radiation, as do x-rays or computed tomography (CT scans).

A magnetic field is created and pulses of radio waves are sent from a scanner. The radio waves knock the nuclei of the atoms in your body out of their normal position. As the nuclei realign back into proper position, the nuclei send out radio signals. These signals are received by a computer that analyzes and converts them into an image of the part of the body being examined. This image appears on a viewing monitor. Some MRI machines look like narrow tunnels, while others are more open.

Magnetic resonance (MRI) may be used instead of computed tomography (CT) in situations where organs or soft tissue are being studied, because with MRI scanning bones do not obscure the images of organs and soft tissues, as does CT scanning.

New uses and indications for MRI have contributed to the development of additional magnetic resonance technology. Magnetic resonance angiography (MRA) is a new procedure used to evaluate blood flow through arteries in a noninvasive (the skin is not pierced) manner. MRA can also be used to detect intracranial (within the brain) aneurysms and vascular malformations (abnormalities of blood vessels within the brain, spinal cord, or other parts of the body).

Magnetic resonance spectroscopy (MRS) is another noninvasive procedure used to assess chemical abnormalities in body tissues such as the brain. MRS may be used to assess disorders such as HIV infection of the brain, stroke, head injury, coma, Alzheimer's disease, tumors, and multiple sclerosis.

Functional magnetic resonance imaging of the brain (fMRI) is used to determine the specific location of the brain where a certain function, such as speech or memory, occurs. The general areas of the brain in which such functions occur are known, but the exact location may vary from person to person. During functional resonance imaging of the brain, you will be asked to perform a specific task, such as recite the Pledge of Allegiance, while the scan is being done. By pinpointing the exact location of the functional center in the brain, physicians can plan surgery or other treatments for a particular disorder of the brain.

For more in depth information on an MRI procedure, click here to go to INTEGRIS' Health Library.  This link will open in a new window.

What is an electroencephalogram?

An electroencephalogram (EEG) is a test that measures the electrical activity in the brain, called brain waves. An EEG measures brain waves through small button electrodes that are placed on your child's scalp.

What steps should be taken to prepare my child for the EEG?

Consider the following when preparing your child for an EEG:

• Wash your child's hair the night before. Do not put any oil, gel, or hairspray on his/her hair. If your child's hair is long, do not braid or put it up. No hair extensions please.
• To get the maximum information from this test, your child's physician will try to record EEG during wakefulness and sleep.
• Give your child his/her medications as usual. Bring a list of all the medications (dose and schedule) your child takes to the EEG Lab.
  Your child's physicians will give you instructions about when your child can eat before and after the procedure.
• On the day of the EEG, your child should not have any drinks containing caffeine such as caffeinated sodas, coffee, and tea.

For more in depth information on an EEG procedure, click here to go to INTEGRIS' Health Library.  This link will open in a new window.