What is a nuclear medicine scan?
A nuclear medicine scan is a type of imaging exam that uses radioactive material to evaluate activity inside your body. Other types of imaging exams produce pictures of structures like bones and organs, so we see what your body looks like. But a nuclear scan produces pictures of chemical reactions, so we see how your body works.
We can use nuclear medicine and molecular imaging to diagnose and treat a wide range of conditions, including cancer, heart disease, and thyroid disease. Nuclear scans can often help us detect and diagnose diseases in their early stages, before signs would be visible on other imaging scans. Nuclear medicine imaging is also useful for planning certain surgeries and evaluating the effectiveness of treatment.
How a nuclear medicine scan works
A nuclear scan works by using radioactive tracers to pinpoint areas of your body that contain a high or low amount of biochemical activity, which often indicates disease. The tracer contains radioactive molecules. We usually inject the tracer into your body, or you may swallow or inhale it. We track where and how the tracer interacts with your cells, called “uptake.” Diseased cells absorb the tracer (either high uptake or low uptake) and release gamma rays (a type of energy). A special camera detects the gamma rays and produces images, highlighting areas of abnormal chemical activity.
For example, cancer cells are highly active because they’re dividing rapidly. This results in a higher-than-normal uptake of the tracer, appearing as a “hot spot” on a nuclear scan. On the other hand, hypothyroidism (underactive thyroid) can usually be diagnosed by “cold spots” on a nuclear scan, indicating a lower-than-normal uptake of the tracer.
There are many types of radioactive tracers, also called radiopharmaceuticals or radionuclides. Your health-care provider selects the right tracer for your needs.
Types of nuclear medicine scans
Nuclear medicine scans are often combined with other types of imaging, such as X-ray, CT scan, or MRI, to get more detailed pictures. There are many types of nuclear scans for different parts of the body, including:
- Bone scan: detects tumors, infections, and fractures in bones, as well as cancer that has spread to the bones
- Cardiac scan: measures heart muscle function, heart damage, and evaluates coronary artery disease
- Gallium scan: helps diagnose cancer, inflammation, and infections using a tracer called gallium citrate
- Gastric emptying scan: measures how long it takes for food to leave your stomach, which can help diagnose gastroparesis
- Gastrointestinal bleeding scan: finds the source of internal bleeding in the stomach or intestines
- Multigated acquisition (MUGA) scan: measures ejection fraction (how well your heart pumps blood) to diagnose heart failure
- PET scan: uses a tracer that acts like glucose (sugar) to find areas of high metabolic activity such as cancer
- Single photon emission computed tomography (SPECT) scan: evaluates blood flow to the heart and brain to diagnose vascular and neurological disorders
- Thyroid scan: checks for an overactive or underactive thyroid gland to diagnose thyroid nodules or cancer
Who might need a nuclear medicine scan?
We may recommend a nuclear scan to diagnose:
- Blood flow problems in your lungs, brain, or heart
- Bone diseases and trauma
- Brain diseases such as Alzheimer’s disease, epilepsy, or dementia
- Cancer that has spread or returned after treatment
- Coronary artery disease and blocked blood vessels
- Gallbladder inflammation
- Gastrointestinal bleeding
- Lung conditions and breathing problems
- Neurological disorders such as Parkinson’s disease
What to expect during a nuclear medicine scan
Most nuclear medicine scans take place at hospitals and some outpatient imaging facilities. A nuclear medicine technologist performs your scan. A radiologist with specialized training in nuclear medicine and molecular imaging interprets the results.
Your care team will tell you how to prepare for your nuclear scan. There may be special instructions about taking medication, eating, or drinking depending on the type of exam you need.
Be sure to tell your technologist if you’re pregnant or breastfeeding. Some types of scans pose a risk to the fetus (unborn baby). You may need to pump breastmilk before the exam and wait for the radiotracer to leave your system before breastfeeding again.
The scan itself typically takes between 30 minutes and one hour. However, it can take anywhere from a few minutes to several hours for the radioactive tracer to travel through your body. Some scans even take place in stages over several days. The total time depends on the type of scan you need.
During a nuclear imaging exam, here’s what you can expect:
- You remove all clothing and jewelry, put on a gown, and lie down on a padded table.
- A nurse or technologist gives you the radioactive tracer as an injection, pill, liquid, or inhaler.
- You wait for the tracer to travel through your body, which may make you feel cold.
- The camera or scanner may be donut-shaped, or it might have a head or arm that passes over or rotates around your body.
- Your technologist steps into another room and takes a series of images.
After a nuclear medicine scan
There’s usually no recovery time after a nuclear medicine scan. Your arm may feel sore if you receive the radioactive tracer as an injection. Side effects from tracers aren’t common, but can include nausea, vomiting, or an allergic reaction, such as a rash or itchy skin.
Does a nuclear medicine scan have risks?
Nuclear scans are safe and use a very small amount of radioactive material in the tracer. Your health-care provider only recommends a nuclear scan if it’s medically necessary and uses the lowest possible radiation dose. The main benefit of nuclear scans—finding diseases early, before they’re detectable with other diagnostic tests—outweighs the risk of radiation exposure.
Nuclear medicine scans tailored to your health at Penn Medicine
At Penn Medicine, we combine the most sophisticated nuclear medicine and molecular imaging technology with the skills and expertise of a world-renowned radiology team. Specialists across multiple areas work together to deliver accurate diagnoses and effective treatment. We offer:
- Focus on quality: We are fully accredited in nuclear medicine and PET by the American College of Radiology (ACR). ACR accreditation is the gold standard for imaging safety and quality. We also use the most up-to-date equipment and ensure our staff is well trained.
- Expert team: Our team includes physicians certified by the American Board of Nuclear Medicine, as well as biologists, pharmacists, physicists, and chemists. We also have a nuclear radiology fellowship program, which means we provide advanced training to the next generation of nuclear radiologists.
- Research and innovation: Penn Medicine has long been an international leader in nuclear imaging and is often the first to introduce new techniques. We participate in clinical trials and research to make the latest advances in nuclear medicine available to our patients.
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