Is a Bone Scan?
A bone scan is an imaging test. It safely uses a very small
amount of radioactive dye to help diagnose problems with your bones.
Specifically, this test is done to reveal problems with bone
metabolism. Bone metabolism refers to the process in which bones break down and
rebuild themselves. New bone formation is part of the healing process when bones
are injured or broken. The bone scan is a good way to view and document
abnormal metabolic activity in the bones.
A bone scan can also be used to determine whether cancer has
spread to the bones from another area of the body, such as the prostate or
During a bone scan, a radioactive dye is injected into your
bones. You’ll then be monitored for several hours. A very small amount of
radiation is used in the dye, and nearly all of it is released from your body
within two or three days.
Is a Bone Scan Performed?
Your doctor may order a bone scan if they think you have a problem
in your bones. A bone scan can also help find the cause of any unexplained bone
pain you’re experiencing.
Bone scans may reveal bone problems associated with the following
- avascular necrosis (when bone tissue dies due to
a lack of blood supply)
- bone cancers
- cancer that has spread to the bone from other parts
of the body
- fibrous dysplasia (a condition that causes
abnormal scar-like tissue to grow in place of normal bone
- infection involving the bone
disease of the bone (a disease that causes weak, deformed bones)
Are the Risks of a Bone Scan?
A bone scan carries no greater risk than conventional X-rays. The
tracers in the radioactive dye used in a bone scan produce very little
radiation exposure. Even the risk of having an allergic reaction to the tracers
However, the test may be unsafe for pregnant or breast-feeding
women. There is a risk of injury to the fetus and of contaminating the breast
milk. Make sure to tell your doctor if you’re pregnant or breast-feeding.
Do I Prepare for a Bone Scan?
A bone scan requires no special preparation. Before the scan,
your doctor will ask you to take off jewelry with metal, including body
The actual screening procedure takes about an hour. Your doctor
may give you a mild sedative to help you relax if you think you’ll have
problems sitting still for that amount of time.
Is a Bone Scan Performed?
The procedure begins with an injection of radioactive dye in your
arm. The dye is then allowed to work its way through your body for the next two
to four hours. Depending on the reason for the bone scan, your doctor may begin
As the dye spreads through your body, the bone’s cells naturally gravitate
to areas that need repair. The dye’s radioactive tracers follow these cells and
collect in spots where bone is damaged.
After enough time has passed, your doctor will use a special
camera to scan the bones. The damaged areas — where the dye has settled — appear
as dark spots on the image.
Your doctor may repeat the injection and imaging process if the
first round wasn’t conclusive. They may also order a single-photon emission
computed tomography (SPECT). This is similar to a bone scan, except the imaging
process creates 3-D images of your bones. A SPECT is necessary if your doctor
needs to see deeper into your bones. They may also use it if the original
images weren’t clear in certain areas.
Do the Results Mean?
Test results are considered normal when the dye is spread evenly
throughout the body. This means that you likely don’t have a major bone
Results are considered abnormal when the scan shows darker “hot
spots” or lighter “cold spots” in the bones. Hot spots describe places where an
excess of dye has collected. Cold spots, on the other hand, are areas where the
dye didn’t collect at all. Abnormal results can indicate that you have a bone
disorder, such as cancer or arthritis.
Up After a Bone Scan
A bone scan doesn’t cause any side effects or complications. Most
of the radioactive tracer in the dye is eliminated from your body within 24
hours. Small amounts may remain for as long as three days.
While the test can help identify problems in bone metabolism, it
doesn’t necessarily reveal the reason for them. You may have to undergo more
tests if the bone scan showed abnormalities. Your doctor will explain your
options and help guide you through the process.