Nuclear medicine is imaging that uses small amounts of radioactive material to diagnose or treat a variety of diseases, including many types of cancers, heart disease and other abnormalities within the body.
Nuclear medicine imaging is unique, because it provides information about both structure and function. Nuclear medicine imaging procedures often identify abnormalities very early in the progress of a disease, long before many medical problems are apparent with other diagnostic tests.
About nuclear medicine
- Nuclear medicine is a safe and painless way to gather information that may be unavailable from other types of tests.
- Radiopharmaceuticals are introduced into the patient’s body by injection, swallowing or inhalation. They give off energy in the form of gamma rays.
- A gamma camera detects these emissions in the organ, bone or tissues.
- 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.
What can a nuclear medicine exam tell my doctor?
A unique aspect of nuclear medicine is that it can both detect structure and function of the area being studied. This sensitivity often enables a nuclear medicine test to show an abnormality very early in the progression of some diseases, even before the problem would become apparent with other examinations.
Nuclear medicine imaging scans are performed to:
- Analyze kidney function
- Visualize heart blood flow and function, including after a heart attack
- Scan lungs for respiratory and blood flow problems
- Identify gallbladder obstructions
- Evaluate bones for fractures, infection, arthritis, density and tumors before they can be seen on an X-ray
- Investigate abnormalities in the esophagus and intestines
- Study abnormal lesions
- Look at whether brain cells function properly, including the sites of seizures, Parkinson’s disease and Alzheimer’s disease
- Determine the presence or spread of cancer in various parts of the body
- Identify bleeding into the bowel
- Evaluate the openness of tear ducts and shunts in the brain and heart
- Locate infections
Nuclear medicine therapies are also available. They include treatment of:
- Hyperthyroidism (overactive thyroid gland, for example, Graves' disease) and thyroid cancer
- Blood disorders
- Painful tumor metastases to the bones
- Adrenal gland tumors in adults and nerve tissue tumors in children
How do I prepare for my exam?
Instructions vary for each nuclear medicine scan, so you will be given detailed instruction during pre-registration.
Tell the tech if you have any allergies, recent illnesses and other medical conditions. If so, adjustments may need to be made for the procedure. Also, be sure to tell the tech if you are pregnant or are breastfeeding. Nuclear medicine tests usually are not recommended for pregnant women.
You should also inform your physician and the tech performing your exam of any medications you are taking, including vitamins and herbal supplements. You may be asked to remove jewelry and other metallic accessories that can interfere with images.
What should I expect during my exam?
Most nuclear medicine procedures are painless and are rarely have any significant discomfort or side effects.
If your scan requires an IV, the tech will insert an IV line into a vein in your hand or arm. Depending on the type of nuclear medicine exam, the dose of radiotracer is then injected intravenously, swallowed or inhaled as a gas. 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.
It can take anywhere from several seconds to several days for the radiotracer 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.
Once in the body, tracers give off emissions that can be detected by a device called a gamma camera. The camera transforms the emissions into images that provide information about the anatomy and function of the body part being imaged.
You will be positioned on an examination table. When it’s time for 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. 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.
If a probe is used, this small hand-held device will be passed over the area of the body being studied to measure levels of radioactivity. Other nuclear medicine tests measure radioactivity levels in blood, urine or breath.
Actual scanning time for nuclear imaging exams can take from 20 minutes to several hours and may be conducted over several days. However, most tests take from 30 to 60 minutes.
When the examination is completed, you may be asked to wait until the tech checks the images in case additional images are needed. Occasionally, more images are obtained for clarification or better visualization of certain areas or structures.
After the scan it is best to drink lots of fluids and urinate as often as possible because this removes any left over radioactivity from the body. You may be instructed to take special precautions after urinating, to flush the toilet twice and to wash your hands thoroughly.
You will be informed by your medical team about further instructions.
Are there risks?
Nuclear medicine is a safe and painless way to gather information that may be otherwise unavailable from other types of tests. Often, physicians will pair information gathered from nuclear medicine with images from other exams, such as an MRI, CT scan or X-ray to better diagnose their patient.
The radiation that patients are exposed to during a nuclear medicine procedure is equal to or less than a standard X-ray or CT scan covering the same body area.
Through the natural process of radioactive decay, the radiotracer 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.
Speak to your tech for instruction about any restrictions following your exam.
How will I find out the results?
After the exam, your nuclear medicine scans will be reviewed by a radiologist, a physician who specializes in the interpretation of diagnostic medical images. Your personal physician will receive a report of the radiologist's findings.