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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)
Kidney disease
Chronic kidney disease is the slow loss of kidney function over time. The main job of the kidneys is to remove wastes and excess water from the body...
ImageRead Article Now Book Mark Article - Recently placed artificial joint
-
A blood vessel
stent
Stent
A stent is a tiny tube placed into a hollow structure in your body. This structure can be an artery, a blood vessel, or something such as the tube t...
ImageRead Article Now Book Mark Article - 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)
Subarachnoid
Subarachnoid hemorrhage is bleeding in the area between the brain and the thin tissues that cover the brain. This area is called the subarachnoid sp...
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-
Infection, such as
brain abscess
Brain abscess
A brain abscess is a collection of pus, immune cells, and other material in the brain, usually from a bacterial or fungal infection.
ImageRead Article Now Book Mark Article - Tumors (cancerous and noncancerous)
-
Hormonal disorders (such as
acromegaly
,
galactorrhea
, and
Cushing syndrome
)
Acromegaly
Acromegaly is a condition in which there is too much growth hormone in the body.
ImageRead Article Now Book Mark ArticleGalactorrhea
Nipple discharge is any fluid that comes out of the nipple area in your breast.
ImageRead Article Now Book Mark ArticleCushing syndrome
Cushing syndrome is a disorder that occurs when your body has a high level of the hormone cortisol.
ImageRead Article Now Book Mark Article -
Multiple sclerosis
Multiple sclerosis
Multiple sclerosis is an autoimmune disease that affects the brain and spinal cord (central nervous system).
ImageRead Article Now Book Mark Article -
Stroke
Stroke
A stroke occurs when blood flow to a part of the brain stops. A stroke is sometimes called a "brain attack. " If blood flow is cut off for longer th...
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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
Dementia
Dementia is a loss of brain function that occurs with certain diseases. It affects memory, thinking, language, judgment, and behavior.
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A special type of MRI called magnetic resonance angiography ( MRA ) may be done to look at blood vessels in the brain.
MRA
Magnetic resonance angiography (MRA) is an MRI exam of the blood vessels. Unlike traditional angiography that involves placing a tube (catheter) int...
What Abnormal Results Mean
Abnormal results may be due to:
-
Abnormal blood vessels in the brain (
arteriovenous malformations of the head
)
Arteriovenous malformations of the head
A cerebral arteriovenous malformation (AVM) is an abnormal connection between the arteries and veins in the brain that usually forms before birth....
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Tumor of the nerve that connects the ear to the brain (
acoustic neuroma
)
Acoustic neuroma
An acoustic neuroma is a slow-growing tumor of the nerve that connects the ear to the brain. This nerve is called the vestibular cochlear nerve. It...
ImageRead Article Now Book Mark Article - Bleeding in the brain
- Brain infection
-
Bulging of the blood vessel in the brain (
aneurysm
)
Aneurysm
An aneurysm is a weak area in the wall of a blood vessel that causes the blood vessel to bulge or balloon out. When an aneurysm occurs in a blood ve...
ImageRead Article Now Book Mark Article - Brain tissue swelling
-
Brain tumors
Brain tumors
A metastatic brain tumor is cancer that started in another part of the body and has spread to the brain.
ImageRead Article Now Book Mark Article - Damage to the brain from an injury
-
Fluid collecting around the brain (
hydrocephalus
)
Hydrocephalus
Hydrocephalus is a buildup of fluid inside the skull that leads to brain swelling. Hydrocephalus means "water on the brain. "
ImageRead Article Now Book Mark Article -
Infection of the skull bones (
osteomyelitis
)
Osteomyelitis
Osteomyelitis is a bone infection. It is mainly caused by bacteria or other germs.
ImageRead Article Now Book Mark Article - Loss of brain tissue
-
Multiple sclerosis
Multiple sclerosis
Multiple sclerosis is an autoimmune disease that affects the brain and spinal cord (central nervous system).
ImageRead Article Now Book Mark Article -
Stroke or transient ischemic attack (
TIA
)
TIA
A transient ischemic attack occurs when blood flow to a part of the brain stops for a brief time. A person will have stroke-like symptoms for up to ...
ImageRead Article Now Book Mark Article - 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
Head CT scan
A head computed tomography (CT) scan uses many x-rays to create pictures of the head, including the skull, brain, eye sockets, and sinuses.
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Positron emission tomography (
PET
) scan of the brain
PET
A brain positron emission tomography (PET) scan is an imaging test of the brain. It uses a radioactive substance called a tracer to look for disease...
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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 - illustration
The major areas of the brain have one or more specific functions.
Brain
illustration
-
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 - 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 - illustration
The major areas of the brain have one or more specific functions.
Brain
illustration
-
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 - 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
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.
