Magnetic resonance imaging (MRI) is a test that uses a magnetic field and pulses of radio wave energy to take pictures of the head. In many cases MRI gives information that cannot be seen on an X-ray, ultrasound, or computed tomography (CT) scan.

For an MRI test, you lie with your head inside a special machine (scanner) that has a strong magnet. The MRI can show tissue damage or disease, such as infection, inflammation, or a tumor. Information from an MRI can be saved and stored on a computer for more study. Photographs or films of certain views can also be made. See MRI images of a person who has had a stroke or a seizure.

In some cases, a dye (contrast material) may be used during the MRI to show pictures of structures more clearly. The dye may help show blood flow, look for some types of tumors, and show areas of inflammation.

MRI of the head may be used to look for the cause of headaches. For more information, see:

Should I have imaging tests to look for the cause of my headaches?

See pictures of a standard MRI machine and an open MRI machine.

Health Tools

Health Tools help you make wise health decisions or take action to improve your health.

Decision Points focus on key medical care decisions that are important to many health problems.

Why It Is Done

Magnetic resonance imaging (MRI) of the head is done to:

• Look for the cause of headaches.
• Help diagnose a stroke or blood vessel problems in the head. Problems with blood vessels may include an aneurysm or abnormal twisted blood vessels that are present at birth (this is called an arteriovenous [AV] malformation).
• Check blood flow or blood clots to the brain. MRI can show bleeding in or around the brain.
• Check symptoms of a known or suspected head injury.
• Check symptoms such as change in consciousness, confusion, or abnormal movements. These symptoms may be caused by brain diseases, such as Huntington's disease, multiple sclerosis (MS), Parkinson's disease, or Alzheimer's disease. See an MRI showing MS in the brain.
• Check for "water on the brain" (hydrocephaly).
• Look for tumors, infections, an abscess, or conditions of the brain or brain stem, such as encephalitis or meningitis.
• Check the eyes, the nerves from the eyes to the brain (optic nerves), the ears, and the nerves from the ears to the brain (auditory nerves).
• Look for problems of the pituitary gland.
• Investigate or follow a finding seen on another test.