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Programs & Services
Nuclear Medicine
Definition
Nuclear medicine (also called radionuclide imaging) uses small amounts of radioactive material to diagnose or treat a variety of diseases, including many types of cancers, heart disease and certain other abnormalities within the body.
Nuclear medicine procedures are noninvasive and usually painless medical tests that help physicians diagnose medical conditions. These imaging scans use radioactive materials called radiopharmaceuticals or radiotracers.
Procedure
Depending on the type of nuclear medicine exam you are undergoing, the radiotracer is either injected into a vein, swallowed or inhaled as a gas and eventually accumulates in the organ or area of your body being examined, where it gives off energy in the form of gamma rays. This energy is detected by a device called a gamma camera or probe. These devices work together with a computer to measure the amount of radiotracer absorbed by your body and to produce special pictures offering details on both the structure and function of organs and tissues.
Common Uses
Physicians use these procedures to visualize the structure and function of an organ, tissue, bone or system of the body.
Nuclear medicine imaging scans are performed to:
- analyze kidney function.
- visualize heart blood flow and function (such as a myocardial perfusion scan).
- scan lungs for respiratory and blood flow problems.
- identify inflammation in the gallbladder.
- evaluate bones for fractures, infection, arthritis and tumors.
- determine the presence or spread of cancer in various parts of the body.
- identify bleeding into the bowel.
- locate the presence of infection.
- measure thyroid function to detect an overactive or underactive thyroid.
- investigate abnormalities in the brain, such as seizures, memory loss and abnormalities in blood flow.
- localize the lymph nodes before surgery in patients with breast cancer or melanoma.
Nuclear medicine therapies include:
Radioactive iodine (I-131) therapy used to treat hyperthyroidism (overactive thyroid gland, for example, Graves' disease) and thyroid cancer.
How It Works
With ordinary x-ray examinations, an image is made by passing x-rays through your body from an outside source. In contrast, nuclear medicine procedures use a radioactive material called a radiopharmaceutical, which is injected into your bloodstream, swallowed or inhaled. This radioactive material accumulates in the organ or area of your body being examined, where it gives off a small amount of energy in the form of gamma rays. A gamma camera or probe detects this energy and with the help of a computer creates pictures offering details on both the structure and function of organs and tissues in your body.
Unlike other imaging techniques, nuclear medicine imaging studies are less directed toward picturing anatomy and structure, and more concerned with depicting physiologic processes within the body, such as rates of metabolism or levels of various other chemical activity. Areas of greater intensity, called "hot spots", indicate where large amounts of the radiotracer have accumulated and where there is a high level of chemical activity. Less intense areas, or "cold spots", indicate a smaller concentration of radiotracer and less chemical activity.
In radioactive iodine (I-131) therapy, radioactive iodine (I-131) is swallowed, absorbed into the bloodstream in the gastrointestinal (GI) tract and concentrated from the blood by the thyroid gland where it destroys cells within that organ.
How the procedure is performed
Nuclear medicine imaging is usually performed on an outpatient basis, but is often performed on hospitalized patients as well.
You will be positioned on an examination table. If necessary, a technologist will insert an intravenous (IV) line into a vein in your hand or arm.
Depending on the type of nuclear medicine exam you are undergoing, the dose of radiotracer is then injected intravenously, swallowed or inhaled.
It can take anywhere from several seconds to several days for the radiopharmaceutical to travel through your body and accumulate in the organ or area being studied. As a result, imaging may be done immediately, a few hours later, or even several days after you have received the radioactive material.
How prepare for the test
- You may be asked to wear a gown during the exam or you may be allowed to wear your own clothing.
- Women should always inform their physician or technologist if there is any possibility that they are pregnant or if they are breastfeeding their baby.
- You should inform your physician and the technologist performing your exam of any medications you are taking, including vitamins and herbal supplements.
- You should also inform them if you have any allergies and about recent illnesses or other medical conditions.
- Jewelry and other metallic accessories should be left at home if possible or removed prior to the exam because they may interfere with the procedure.
You will receive specific instructions based on the type of scan you are undergoing.
During the Procedure
- When it is time for the imaging to begin, the gamma camera will take a series of images.
- The camera may rotate around you or it may stay in one position and you will be asked to change positions in between images.
- While the camera is taking pictures, you will need to remain still for brief periods of time. It is important that you remain still while the images are being recorded.
- In some cases, the camera may move very close to your body. This is necessary to obtain the best quality images.
- If you are claustrophobic, you should inform the technologist before your exam begins.
The length of time for nuclear medicine procedures varies greatly, depending on the type of exam. Actual scanning time for nuclear imaging exams can take from 20 minutes to several hours and may be conducted over several days.
After the Procedure
When the examination is completed, you may be asked to wait until the technologist checks the images in case additional images are needed. Occasionally, more images are obtained for clarification or better visualization of certain areas or structures. The need for additional images does not necessarily mean there was a problem with the exam or that something abnormal was found, and should not be a cause of concern for you. You will not be exposed to more radiation during this process.
If you had an intravenous line inserted for the procedure, it will be removed.
During radioactive iodine (I-131) therapy, which is most often an inpatient procedure, the radioactive iodine is swallowed in capsule form.
What will I experience during and after the procedure
Most nuclear medicine procedures are painless and are rarely associated with significant discomfort or side effects.
If the radiotracer is given intravenously, you will feel a slight pin prick when the needle is inserted into your vein for the intravenous line. When the radioactive material is injected into your arm, you may feel a cold sensation moving up your arm, but there are generally no other side effects.
When swallowed, the radiotracer has little or no taste. When inhaled, you should feel no differently than when breathing room air or holding your breath.
With some procedures, a catheter may be placed into your bladder, which may cause temporary discomfort.
Though nuclear imaging itself causes no pain, there may be some discomfort from having to remain still or to stay in one particular position during imaging.
Unless your physician tells you otherwise, you may resume your normal activities after your nuclear medicine scan. If any special instructions are necessary, you will be informed by a technologist before you leave the nuclear medicine department.
Radioactive Material
Through the natural process of radioactive decay, the small amount of radiopharmaceutical in your body will lose its radioactivity over time. It may also pass out of your body through your urine or stool during the first few hours or days following the test. You may be instructed to take special precautions after urinating, to flush the toilet twice and to wash your hands thoroughly. You should also drink plenty of water to help flush the radioactive material out of your body as instructed by the nuclear medicine personnel.