 A
bone scan is sometimes performed to rule out an inflammatory process
(such as a tumor or infection) or an occult fracture (small fracture
not seen on an x-ray).
 A
bone scan is performed by injecting a small amount of radioactive
marker into an intravenous line (IV). Three hours later the patient is
placed through a scanner and the radioactive marker will be
concentrated in any region where there is high bone turnover.
A bone scan is a highly sensitive test to pick
up tumors, infections, or very small fractures because these
conditions all result in high bone turnover. It can also be used to
determine if a compression fracture of the vertebral body is old or
new, as an old fracture will not light up and a new one will.
Bone scans, however, cannot distinguish what a
lesion represents, and therefore cannot differentiate between a tumor,
an infection or a fracture. Therefore, this type of imaging study
usually needs to be followed by a CT scan and/or MRI scan to better
characterize the lesion.
The results of the
test reveal 'hot' and 'cold' spots. Hot spots appear darker on the
image and denote an area of high tracer uptake, possibly indicating an
abnormality (e.g. infection). Cold spots appear light and indicate the
bone absorbed less of the tracing element. 
In many departments, the bone scan is one of
the most commonly performed nuclear medicine diagnostic procedure.
X-rays, CT scans and MRI examinations evaluate the structure of the
bone. In contrast, a bone scan evaluates the functional aspect of the
bone diseases. This is very useful in the early diagnosis of a stress
fracture when the changes in bone architecture have not taken place
yet, but the bone scan is frequently abnormal at that stage. This
provides the physician an opportunity to make the diagnosis early,
thereby expediting treatment.
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There are a variety of situations when a
bone scan would be useful. These include but are not limited to,
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Diagnosis of bone infection, known as
osteomyelitis.
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Diagnosis of stress injuries, such as a
stress fracture and shin splints.
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In patients with cancer, to determine
whether the cancer has spread to the bone or not. Therapeutic
options in these patients are often determined by whether or not the
cancer has involved the bones. Bone scanning is particularly useful
because it is possible to evaluate the entire skeleton with a single
examination.
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In the evaluation of unexplained bone pain.
When you come to nuclear medicine department,
you will receive an injection of a radioactive compound (such as
Technetium-99m MDP or Technetium-99m HDP). In certain situations (such
as for diagnosis of osteomyelitis), imaging is performed at the time
of injection. Otherwise, you can leave the department soon after the
injection, and you will be asked to return two hours later for
imaging. This is done to allow time for the injected compound to
localize in the bones. Depending on the type of information desired,
it takes 30 to 90 minutes to perform the scan. When you come to the
department you will be provided with the information that will
include, based on the information desired by your referring physician,
an estimate of how long it will take to perform the scan.
While performing the bone scan, side effects
are not common, and when encountered are usually mild, such as nausea
and vomiting. If you are pregnant, suspect you may be, or are a
nursing mother, please discuss this with your physician before
scheduling the test.
There is no preparation prior to a bone scan. If you are taking any
medications routinely, you can continue to do so on the day of the
bone scan procedure. Unless you are having another procedure that
requires you to avoid food, you can have your regular meals before
coming to the department. You will be encouraged to drink plenty of
fluids (water, soft drinks, juices etc) between the time of injection
and the scan which typically will be performed 2-3 hours later. You
will also be asked to empty your bladder frequently. |
