What is Nuclear Medicine?
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?
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?
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.
How is the procedure performed?
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?
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?
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?
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?
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.
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