What Is a Head MRI?
resonance imaging (MRI) of the head is a painless, noninvasive test that
produces detailed images of your brain and brain stem. An MRI machine creates
the images using a magnetic field and radio waves. This test is also known as a
brain MRI or a cranial MRI. You will go to a hospital or radiology center to
take a head MRI.
An MRI is
different from a CT scan or an X-ray in that it doesn’t use radiation to
produce images. An MRI combines images to create a 3-D picture of your internal
structures, so the MRI is more effective than other scans at detecting
abnormalities in the pituitary gland and brain stem.
Why Do I Need a Head MRI?
A head MRI
is a useful tool for detecting a number of brain conditions, including:
(bulging in the blood vessels of the brain)
(a buildup of spinal fluid in the brain cavities)
disorders (such as acromegaly and Cushing syndrome)
with development or structure
A head MRI
can help determine whether you sustained any damage from a stroke or head
injury. Your doctor may also order a head MRI to investigate symptoms such as
dizziness, weakness, seizures, changes in thinking or behavior, blurry vision,
or chronic headaches. These symptoms may be due to a brain issue, which an MRI
can help detect.
MRI, or fMRI, of the brain is useful for people who might have to undergo brain
surgery. An fMRI can pinpoint areas of the brain responsible for speech and
language, and body movement. It does this by measuring metabolic changes that
take place in the brain when you perform certain tasks. During this test, you
may need to carry out small tasks, such as answering basic questions or tapping
your thumb with your fingertips.
there is a type of MRI called magnetic resonance angiography (MRA), which
examines certain blood vessels in the brain.
How Do I Prepare for a Head
staff will need to know if you have inner ear implants, artificial joints, a defibrillator
or pacemaker, particular types of heart valves, vascular stents, brain aneurysm
clips, or if you have ever worked with sheet metal. All of these things can
affect the outcome of an MRI. In the case of implants and pacemakers, those
items can stop working properly due to an MRI’s magnetic field.
wearing anything that contains metal, including jewelry or sunglasses, you will
need to remove these items. Metal interferes with the MRI machine’s ability to
produce a clear image. Braces and dental fillings will typically not pose a
problem, but pocketknives, pens, pins, and certain dental appliances can
interfere. The staff may ask you to wear a hospital gown or clothing that
doesn’t contain metal fasteners. You can’t have electronic devices in the MRI
You may have
to refrain from eating or drinking anything for four to six hours before the
medical staff if you’re pregnant. An MRI’s magnetic field affects unborn
children in a way that isn’t yet fully understood.
it’s important to let the staff know if you have claustrophobia. If you’re
claustrophobic, you might need to use sedatives during the exam or have an
“open” MRI. Open MRI machines have wider tunnels, which tend to be more
tolerable for claustrophobic patients.
What Is the Procedure for a
exam, it’s important to stay still to obtain the clearest images. Children who
have difficulty staying still may need intravenous or oral sedation. Sedation
can also be helpful for adults who are claustrophobic.
You will lie
down on a table that slides into the MRI machine. The table slides through a
large magnet shaped like a tube. You may have a plastic coil placed around your
head. After the table slides into the machine, a technician will take several
pictures of your brain, each of which will take a few minutes. There will be a
microphone in the machine that allows you to communicate with the testing
normally takes 30 to 60 minutes. You may receive a contrast solution, usually
gadolinium, intravenously to allow the MRI machine to see certain parts of the
brain more easily, particularly your blood vessels. The MRI scanner will make
loud banging noises during the procedure. You may wear earplugs or headphones
to block the MRI machine’s noises, or you may listen to music during the test.
There are no
risks associated with the MRI itself. There is a very slight chance that you will
have an allergic reaction to a contrast solution. Tell the medical staff if you
have decreased kidney function; it may not be safe to use contrast solution if
this is the case.
What Happens After a Head
test, you can get dressed and leave the testing facility. If you were sedated
for the exam, staff may move you to a recovery area until you wake up — usually
one to two hours after you received the sedative.
radiologist will analyze your MRI images. They will provide your doctor with
the results. Your results will be available quickly if your head MRI was an
emergency procedure. Next steps will depend on whether the results revealed
anything unusual or discovered the cause of any abnormalities.