Magnetic Resonance Angiography (MRA)
What is it?
Magnetic resonance angiography (MRA) is a painless
diagnostic test that uses a specific sequence of radio
signals to produce extremely detailed images of blood flow
inside the body. It is a type of magnetic resonance
imaging (MRI) that looks at the blood vessels and blood
flow within the brain and head without injecting any
radioactive dyes or inserting a catheter into a blood
vessel.
Who needs this procedure?
MRA is used to detect blood clots and aneurysms in the
brain, as well as arterial aneurysm and abnormalities in
blood vessels that supply the major organs of the body. It
is also used to detect narrowed or blocked carotid
arteries, located on either side of the neck, which is a
leading cause of stroke.
How do I prepare for this procedure?
While there are no special preparations for this
procedure, there are some cases in which MRA/MRI may not
be recommended. You cannot have MRA/MRI if you have any
metal in your body, such as metal plates, pins, or
fragments, which will attract the magnet. You also cannot
have MRA/MRI if you have a pacemaker because the magnetic
waves may damage it. The effects of magnetic waves on an
unborn child have not been determined. For this reason,
you should let your doctor know if you are pregnant before
having this procedure. Also tell your doctor know if you
have difficulty being in small spaces (claustrophobia).
How is this procedure performed?
Before the procedure begins, you will be asked to
remove any clothes that have any metal fasteners, such as
zippers, snaps, or hooks, and put on a gown. You will also
need to remove any metal jewelry. During the procedure,
you may be monitored for vital signs, such as respiration
and heart rate. An MRI machine looks like a large, hollow
tube with a padded table sticking out of it. As you lie on
the table, it moves slowly into the tube. It is very
important that you lie very still during the test or the
pictures will be blurry. You may be gently strapped to the
table to help you lie still. Right outside of the MRI room
is a smaller room with a window in it. The radiologist
sits in this room and controls the MRI equipment. A
microphone allows the radiologist to talk to you
throughout the procedure. During the MRA, the machine
directs magnetic and radio waves at the part of your body
that is being studied. You cannot feel these waves, but as
they pass through your body they create a picture that is
seen on a computer monitor. Many pictures are taken, and
each one provides a view of a different layer of your
body. An MRI machine is noisy. You will be given earphones
to wear so you can listen to music during the procedure.
If you are claustrophobic, your doctor may give you a mild
sedative before the test. Or, you may be able to have an
open MRI, which does not require you to be inside a tube.
If your doctor determines that you need to be injected
with a dye (contrast agent) to provide a better picture,
the type of dye used carries a low risk of allergic
reaction. However, tell your doctor if you have had any
allergic reactions to dyes in the past. In most cases, MRA
takes between 30 and 90 minutes.
What can I expect after the procedure?
MRA has no side effects. Your healthcare provider will
notify you when he or she has received the results.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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