Skeletal MRI Scan
uses a strong magnetic field combined with radiofrequency waves
to create highly detailed, cross-sectional
images of selected bones and surrounding tissues. These scans,
which appear as two-dimensional slices through the bone, are
then examined for abnormalities. For certain studies, an
MRI contrast dye such as gadolinium may be injected to provide
better definition of soft tissues and blood vessels and thus
enhance the images.
Purpose of the Test
tumors of the bone or the soft tissue inside or around the bone,
such as muscles and ligaments.
any changes in the bone marrow cavity.
To assess various
disorders of the spine, spinal cord, spinal nerves, or intervertebral
discs, and to evaluate the spine before surgery.
To help diagnose meniscal
tears in the knee, as well as injuries of the knee and shoulder
Who Performs It
A radiologist or a qualified technician.
MRI is more
expensive and less widely available than x-rays or CT scans,
but is preferable in most cases where differentiation of the
soft tissue in and around bones is necessary.
experience claustrophobia may find it difficult to undergo an
MRI, which takes place in a narrow, tunnel-like structure. In
some cases, an open MRIa larger unit that is open on several
sidesmay be used as an alternative.
This test may
not be possible for severely overweight individuals (over 300
lbs), although some open MRI scanners can now accommodate larger
MRI generates a strong magnetic field, it cannot be performed
on people who have certain types of internally placed metallic
devices, including pacemakers, inner ear implants, or intracranial
test is not commonly done in pregnant women because the long-term
effects of MRI on the fetus are unknown.
Before the Test
Tell your doctor
if you suffer from claustrophobia. He or she may prescribe a
sedative that can help you tolerate the procedure.
You will be
advised to empty your bladder before the test.
magnetic cards or metallic objects, including watches, hair clips,
belts, credit cards, and jewelry. You may be asked to disrobe
and put on a hospital gown.
What You Experience
You will lie
down on a narrow, padded bed that slides into a large, enclosed
cylinder containing the MRI magnets.
You must remain
very still throughout the procedure because any motion can distort
In some cases,
you will receive an injection of contrast dye such as gadolinium
before or during the procedure.
There is a
microphone inside the imaging machine, and you may talk to the
technician performing the scan at any time during the procedure.
You will hear
loud thumping sounds as the scanning is performed. To block out
the noise, you can request earplugs or listen to music on earphones.
usually takes from 60 to 90 minutes.
Risks and Complications
MRI does not involve exposure to ionizing radiation
and is not associated with any risks or complications.
After the Test
can go home right after the scan and resume their usual activities.
may be monitored for a short period until the effects of the
sedative have worn off.
The MRI scans
are displayed on a video monitor and then recorded on film. The
doctor will examine the images for signs of any skeletal abnormality.
If a definitive
diagnosis can be made, appropriate treatment will be initiated,
depending on the specific problem.
In some cases,
additional tests, such as a bone biopsy, may be required to establish
a diagnosis or determine the extent of a problem.
From The Johns Hopkins Consumer Guide to Medical
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