If your doctor suspects that your prostate cancer may have spread to other areas of your body, then a bone scan will likely be one of the tests that you undergo.
What Is a Bone Scan?
A bone scan is a test used to detect areas of bone damage due to cancer, infection, or others causes. It can detect bone damage throughout the skeleton.
Why Is a Bone Scan Done?There are several reasons:
- To detect the spread of cancer to the bones.
- To find bone fractures that do not show up on bone x-rays
- To identify areas of bone that are damaged by infection or other bone conditions
- To further evaluate areas that appear abnormal on another test, such as an x-ray, CT scan, or MRI
How Does a Bone Scan Work?
To begin, a small amount of radioactive tracer material is injected into the bloodstream. This tracer material, which is safe for the patient, will give off low levels of radioactivity that can then be detected by a special type of camera known as a gamma camera.
This tracer material is preferentially absorbed by the bones. It typically takes a few hours for enough of the tracer material to be absorbed by the bones, so it is injected early in the morning and pictures are taken by the gamma camera later in the morning or afternoon.
Other than starting the IV line that is necessary to inject the tracer material into your arm, the test is painless.
What Do the Results Mean?
A normal bone scan image is one in which the tracer is evenly dispersed throughout the bones.
Areas of bone that have increased growth or breakdown compared to normal bone will absorb increased amounts of tracer and will appear as “hot spots” in the pictures taken by the gamma camera. Alternatively, areas of bone that do not absorb the tracer will appear as “cold spots.” Both of these areas are abnormal.
Hot spots can be due to a number of conditions including cancer, fracture, infection, certain types of arthritis, and other chronic bone diseases.
Cold spots are less commonly seen, but can be occur in certain types of cancer (such as multiple myeloma) or in certain metabolic bone conditions.
Brant WE and Helms CA: Fundamentals of Diagnostic Radiology. 3rd ed. 2006.