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Head MRI

Nuclear magnetic resonance - cranial; Magnetic resonance imaging - cranial; MRI of the head; MRI - cranial; NMR - cranial; Cranial MRI; Brain MRI; MRI - brain; MRI - head

 

A head MRI (magnetic resonance imaging) is an imaging test that uses powerful magnets and radio waves to create pictures of the brain and surrounding nerve tissues.

It does not use radiation.

How the Test is Performed

 

Head MRI is done in the hospital or radiology center.

You lie on a narrow table, which slides into a large tunnel-shaped scanner.

Some MRI exams require a special dye, called contrast material. The dye is usually given before the test through a vein (IV) in your hand or forearm. The dye helps the radiologist see certain areas more clearly.

During the MRI, the person who operates the machine watches you from another room. The test most often lasts 30 to 60 minutes, but may take longer.

 

How to Prepare for the Test

 

You may be asked not to eat or drink anything for 4 to 6 hours before the scan.

Tell your health care provider if you are afraid of close spaces (have claustrophobia). You may receive medicine to help you feel sleepy and less anxious. Or your provider may suggest an "open" MRI, in which the machine is not as close to the body.

You may be asked to wear a hospital gown or clothing without metal ties (such as sweatpants and a t-shirt). Certain types of metal can cause blurry images.

Before the test, tell your provider if you have:

  • Brain aneurysm clips
  • An artificial heart valves
  • Heart defibrillator or pacemaker
  • Inner ear (cochlear) implants
  • Kidney disease or dialysis (you may not be able to receive contrast)
  • Recently placed artificial joint
  • A blood vessel stent
  • Worked with sheet metal in the past (you may need tests to check for metal pieces in your eyes)
  • Allergy to iodine, which is used in the contrast material

The MRI contains strong magnets. Metal objects are not allowed into the room with the MRI scanner. This includes:

  • Pens, pocketknives, and eyeglasses
  • Items such as jewelry, watches, credit cards, and hearing aids
  • Pins, hairpins, metal zippers, and similar metallic items
  • Removable dental work

 

How the Test will Feel

 

An MRI exam causes no pain. If you have difficulty lying still or are very nervous, you may be given a medicine to relax. Too much movement can blur the images and cause errors.

The table may be hard or cold, but you can ask for a blanket or pillow. The machine makes loud thumping and humming noises when turned on. You can ask for ear plugs to help reduce the noise.

An intercom in the room allows you to speak to someone at any time. Some MRIs have televisions and special headphones that can help you pass the time or block the scanner noise.

There is no recovery time, unless you were given a medicine to relax. After an MRI scan, you can go back to your normal diet, activity, and medicines.

 

Why the Test is Performed

 

An MRI provides detailed pictures of the brain and nerve tissues.

A brain MRI can be used to diagnose and monitor many diseases and disorders that affect the brain, including:

  • Birth defect
  • Bleeding (subarachnoid bleed or bleeding in the brain tissue itself)
  • Family history of aneurysms
  • Infection, such as brain abscess
  • Tumors (cancerous and noncancerous)
  • Hormonal disorders (such as acromegaly, galactorrhea, and Cushing syndrome)
  • Multiple sclerosis
  • Stroke

An MRI scan of the head can also determine the cause of:

  • Muscle weakness or numbness and tingling
  • Changes in thinking or behavior
  • Hearing loss
  • Headaches when certain other symptoms or signs are present
  • Speaking difficulties
  • Vision problems
  • Dementia

A special type of MRI called magnetic resonance angiography (MRA) may be done to look at blood vessels in the brain.

 

What Abnormal Results Mean

 

Abnormal results may be due to:

  • Abnormal blood vessels in the brain (arteriovenous malformations of the head)
  • Tumor of the nerve that connects the ear to the brain (acoustic neuroma)
  • Bleeding in the brain
  • Brain infection
  • Bulging of the blood vessel in the brain (aneurysm)
  • Brain tissue swelling
  • Brain tumors
  • Damage to the brain from an injury
  • Fluid collecting around the brain (hydrocephalus)
  • Infection of the skull bones (osteomyelitis)
  • Loss of brain tissue
  • Multiple sclerosis
  • Stroke or transient ischemic attack (TIA)
  • Structural problems in the brain

 

Risks

 

MRI uses no radiation. To date, no side effects from the magnetic fields and radio waves have been reported.

The most common type of contrast (dye) used is gadolinium. It is very safe. Allergic reactions to the substance rarely occur. However, gadolinium can be harmful to people with kidney problems who are on dialysis. If you have kidney problems, tell your provider before the test.

The strong magnetic fields created during an MRI can make heart pacemakers and other implants not work as well. It can also cause a piece of metal inside your body to move or shift.

 

Considerations

 

MRI is used more often than CT scan. This is because it can easily find defects in the soft tissue. Also, it is safe during pregnancy.

Tests that may be done instead of an MRI of the head include:

  • Head CT scan
  • Positron emission tomography (PET) scan of the brain

A CT scan may be preferred in the following cases, since it is faster and usually available right in the emergency room:

  • Acute trauma of the head and face
  • Bleeding in the brain (within the first 24 to 48 hours)
  • Early symptoms of stroke
  • Skull bone disorders and disorders involving the bones of the ear

 

 

References

Aygun N, Zinreich SJ. Overview of diagnostic imaging of the head and neck. In: Flint PW, Haughey BH, Lund V, et al, eds. Cummings Otolaryngology. 6th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 8.

Chernecky CC, Berger BJ. M. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. Philadelphia, PA: Elsevier Saunders; 2013:750-809.

Wilkinson ID, Graves MJ. Magnetic resonance imaging. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic Radiology. 6th ed. New York, NY: Elsevier Churchill Livingstone; 2015:chap 5.

 
  • Brain

    Brain - illustration

    The major areas of the brain have one or more specific functions.

    Brain

    illustration

  • Head MRI

    Head MRI - illustration

    MRI stands for magnetic resonance imaging. It allows imaging of the interior of the body without using x-rays or other types of ionizing radiation. An MRI scan is capable of showing fine detail of different tissues of the head.

    Head MRI

    illustration

  • Lobes of the brain

    Lobes of the brain - illustration

    Each lobe of the brain has a different set of functions, so damage to a particular lobe may determine the type of problems that could be expected.

    Lobes of the brain

    illustration

    • Brain

      Brain - illustration

      The major areas of the brain have one or more specific functions.

      Brain

      illustration

    • Head MRI

      Head MRI - illustration

      MRI stands for magnetic resonance imaging. It allows imaging of the interior of the body without using x-rays or other types of ionizing radiation. An MRI scan is capable of showing fine detail of different tissues of the head.

      Head MRI

      illustration

    • Lobes of the brain

      Lobes of the brain - illustration

      Each lobe of the brain has a different set of functions, so damage to a particular lobe may determine the type of problems that could be expected.

      Lobes of the brain

      illustration

    A Closer Look

     

      Talking to your MD

       

        Self Care

         

          Tests for Head MRI

           

           

          Review Date: 7/3/2016

          Reviewed By: Jason Levy, MD, Northside Radiology Associates, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

          The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
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