Nuclear medicine is a subspecialty within 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. Radiation to the patient is, generally, 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
- Identify blockage or chronic disease of the gallbladder
- Evaluate bones for fracture, infection, arthritis or tumor
- Determine the presence or spread of cancer
- Locate the presence of infection
- Measure thyroid uptake to detect hyperthyroidism or hypothyroidism
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 the meal immediately 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?
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 gamma camera used during the procedure. It is enclosed in metallic housing designed to facilitate imaging of specific parts of the body. It looks like a large square metallic apparatus with a metal arm that hangs over the examination table.
A nearby computer console processes the data from the procedure.
How does the procedure work?
You are given a compound, usually intravenously but sometimes orally, containing a small amount of a radioactive substance that localizes in specific body organ systems. This compound, called a radiopharmaceutical 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?
A radiopharmaceutical is administered into a vein. Depending on which type of scan is being performed, the imaging will be done either immediately or a few hours or even two 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.
You must remain as still as possible during imaging. If the gamma camera is moved slowly along the body, the resulting image is called a planar scan. Sometimes sequential images are obtained to show how an organ functions over time.
What will I experience during the procedure?
Some discomfort during a nuclear medicine procedure may arise from the intravenous injection, usually done with a small needle. Lying still on the examining table may be unpleasant for some patients.
The radiopharmaceutical loses its radioactivity generally over 24 hours. It passes out of the body in the urine or stool.
Who interprets the results and how do I get them?
Most patients undergo a nuclear medicine examination because a referring physician has recommended it. Our radiologist will interpret the images and fax a report to the referring physician.
What are the benefits of Nuclear Medicine?
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.
Nuclear medicine is much less traumatic than exploratory surgery.
Nuclear Medicine procedures will result in exposure to a small dose of radiation. However, the doses of radiopharmaceutical administered are the smallest possible. Nuclear medicine has been used for more than three 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 Nuclear Medicine?
Nuclear medicine procedures are time-consuming. They involve administration of a radiopharmaceutical, obtaining images, and interpreting the results. It can take hours to days for the radiopharmaceutical to accumulate in the part of the body under study. Imaging can take one to two hours to perform.