Evaluation
for Distant Disease: Imaging Tests
When prostate cancer spreads outside the prostate gland, it may not only
involve nearby organs and structures such as the seminal vesicles
or the bladder. It may also spread, or metastasize,
to areas distant from the prostate gland. The most common
areas of metastasis are pelvic or abdominal lymph nodes (bean-shaped collections
of white blood cells that fight infection or disease) and
the bones, especially of the pelvis, spine and ribs. Prostate
cancer may also spread to the lungs.
Imaging tests take pictures of the inside of the body
using various forms of energy. They are able to see whether
cancer has spread outside the prostate gland and help determine
the clinical stage of the cancer. Imaging tests are conducted
only when metastasis is suspected. Otherwise, imaging tests
are not recommended.
Several imaging tests are available:
- Bone
Scan
A bone
scan shows whether prostate cancer has spread to the
bones. A tiny amount of low-level radioactive material is
injected into the patient's bloodstream. This radioactive
material attaches itself to diseased bone cells throughout
the entire skeleton and shows up as "hot spots" on the bone
scan. Hot spots may mean bone metastasis, but they can also
indicate the presence of arthritis, an old injury, or other
bone diseases. Additional testing may need to be done to
distinguish among those conditions.
- CT
scan
Computed tomography, more commonly known as a CT
or CAT scan, is used to look for abnormally enlarged
lymph nodes where cancer may have spread. The technique
uses a rotating x-ray beam to create a series of pictures
of the body from many angles. A computer combines the information
from all these pictures to produce a detailed cross-sectional
image.
- Magnetic
Resonance Imaging (MRI)
Magnetic resonance imaging (MRI) is used to
see abnormal areas of bone or lymph nodes where prostate
cancer may have spread. An MRI is similar to a CT scan,
except that magnetic fields are used instead of x-rays to
create cross-sectional images of the body.
- ProstaScint
Scan
A ProstaScint scan is similar to a bone scan, but with some
important differences. Instead of looking only at bone,
it can see whether the prostate cancer has spread to other
organs and lymph nodes. In addition, a prostascint scan
can distinguish prostate cancer from other cancers and benign
disorders. A tiny amount of low-level radioactive material,
called a monoclonal antibody, is injected into the
bloodstream. This antibody attaches itself to prostate-specific
membrane antigen, a substance found only in normal and cancerous
prostate cells, turning up "hot spots" on the scan.
The
Prostate Cancer pages of this Web site are part of the Comprehensive
Prostate Cancer Awareness Program (CPCAP), a major regional
effort to reduce the rates of death and illness caused by
prostate cancer in southwestern Pennsylvania. Funding for
CPCAP is provided by a grant from the Commonwealth of Pennsylvania.
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