| General Nuclear Medicine
What is General Nuclear Medicine? Back to Top
Nuclear
medicine is a subspecialty within the field of radiology. It comprises
diagnostic examinations that result in images of body anatomy and
function. The images are developed based on the detection of energy
emitted from a radioactive substance given to the patient, either
intravenously or by mouth. Generally, radiation to the patient is
similar to that resulting from standard x-ray examinations.
What are some common uses of the procedure? Back to Top
Nuclear
medicine images can assist the physician in diagnosing diseases.
Tumors, infection and other disorders can be detected by evaluating
organ function. Specifically, nuclear medicine can be used to:
- Analyze kidney function
- Image blood flow and function of the heart
- Scan lungs for respiratory and blood-flow problems
- Identify blockage of the gallbladder
- Evaluate bones for fracture, infection, arthritis or tumor
- Determine the presence or spread of cancer
- Identify bleeding into the bowel
- Locate the presence of infection
- Measure thyroid function to detect an overactive or underactive thyroid
How should I prepare for the procedure? Back to Top
Usually,
no special preparation is needed for a nuclear medicine examination.
However, if the procedure involves evaluation of the stomach, you may
have to skip a meal before the test. If the procedure involves
evaluation of the kidneys, you may need to drink plenty of water before
the test.
What does the equipment look like? Back to Top
During most
nuclear medicine examinations, you will lie down on a scanning table.
Consequently, the only piece of equipment you may notice is the
specialized nuclear imaging camera used during the procedure. It is
enclosed in metallic housing designed to facilitate imaging of specific
parts of the body. It can look like a large round metallic apparatus
suspended from a tall, moveable post or a sleek one-piece metal arm
that hangs over the examination table. The camera can also be located
within a large, doughnut-shaped structure similar in appearance to a
computed tomography (CT) scanner. Sometimes, the camera is beneath the
table out of view.
A nearby computer console, possibly in another room, processes the data from the procedure.
How does the procedure work? Back to Top
You are given a
small dose of radioactive material, usually intravenously but sometimes
orally, that localizes in specific body organ systems. This compound,
called a radiopharmaceutical agent or tracer, eventually collects in
the organ and gives off energy as gamma rays. The gamma camera detects
the rays and works with a computer to produce images and measurements
of organs and tissues.
How is the procedure performed? Back to Top
A
radiopharmaceutical agent is usually administered into a vein.
Depending on which type of scan is being performed, the imaging will be
done either immediately, a few hours later, or even several days after
the injection. Imaging time varies, generally ranging from 20 to 45
minutes.
The radiopharmaceutical that is used is determined by what part of
the body is under study, since some compounds collect in specific
organs better than others. Depending on the type of scan, it may take
several seconds to several days for the substance to travel through the
body and accumulate in the organ under study, thus the wide range in
scanning times.
While the images are being obtained, you must remain as still as
possible. This is especially true when a series of images is obtained
to show how an organ functions over time.
After the procedure, a physician with specialized training in
nuclear medicine checks the quality of the images to ensure that an
optimal diagnostic study has been performed.
What will I experience during the procedure? Back to Top
Some
minor discomfort during a nuclear medicine procedure may arise from the
intravenous injection, usually done with a small needle. With some
special studies, a catheter may be placed into the bladder, which may
cause temporary discomfort. Lying still on the examining table may be
uncomfortable for some patients.
Most of the radioactivity passes out of your body in urine or stool.
The rest simply disappears through natural loss of radioactivity over
time.
Who interprets the results and how do I get them? Back to Top
Most
patients undergo a nuclear medicine examination because their primary
care physician has recommended it. A physician who has specialized
training in nuclear medicine will interpret the images and forward a
report to your physician. It usually takes a day or so to interpret,
report and deliver the results.
What are the benefits vs. risks? Back to Top
Benefits
- The functional information provided by nuclear medicine
examinations is unique and currently unattainable by using other
imaging procedures. For many diseases, nuclear medicine studies yield
the most useful information needed to make a diagnosis and to determine
appropriate treatment, if any.
- Nuclear medicine is
much less traumatic than exploratory surgery, and allergic reaction to
the radiopharmaceutical material is extremely rare.
Risks
- Because the doses of radiopharmaceutical administered are
very small, nuclear medicine procedures result in exposure to a small
dose of radiation. Nuclear medicine has been used for more than five
decades, and there are no known long-term adverse effects from such
low-dose studies.
- As with all radiologic
procedures, be sure to inform your physician if you are pregnant. In
general, exposure to radiation during pregnancy should be kept to a
minimum.
- Allergic reactions to the radiopharmaceutical can occur, but are extremely rare.
What are the limitations of General Nuclear Medicine? Back to Top
Nuclear
medicine procedures are time-consuming. They involve administration of
a radiopharmaceutical, acquisition of images and interpretation of the
results. It can take hours to days for the radiopharmaceutical to
accumulate in the part of the body under study. Imaging can take up to
three hours to perform, though new equipment is available that can
substantially shorten the procedure time. Back to Top |
