What is Nuclear Medicine?

Nuclear medicine is a branch of medical imaging that uses small amounts of radioactive material, called radionuclides or radiotracers, to create images of the body and study the functionality and appearance of internal organs, tissue, and bone.

How does Nuclear Medicine work?

Normal x-ray examinations create images by passing x-rays through the body from an outside source. In contrast, nuclear imaging involves the use of radiopharmaceuticals to create images of the body. The radiopharmaceuticals (or radiotracers) are injected into the bloodstream, taken by mouth, or inhaled as a gas. The materials accumulate in the area of the body that the physician wishes to visualize, giving off energy in the form of gamma rays. A PET scanner detects this energy and feeds it into a computer, which then creates images of the body.

Unlike x-ray imaging, the primary purpose of nuclear imaging is not to simply picture the internal anatomy of a patient. Nuclear imaging is designed to observe the functionality of the internal processes of the body. Radiologists use nuclear imaging to identify areas where radioactive material has accumulated, these are known as "hot spots" of chemical activity. Some diseases can result in the exclusion of radiotracers, producing what radiologists refer to as a "cold spot". Identification and analysis of these concentrations of radiotracers is what aids in the diagnosis of a multitude of diseases and conditions.

How is Nuclear Medicine used?

Nuclear medicine testing is used for the following diagnostic purposes:

• identify infection: WBC scans - where the patient’s white blood cells(the first line of defense against infection) are extracted from the body, tagged with nuclear material and then re-injected into the patient. The resultant scan shows where the WBC are accumulating, thereby identifying any significant areas of infection.
• Identify active (or inactive) areas of bone growth : Bone scans: here a radio-tagged molecule (the tracer), normally incorporated into any kind of bone growth, is injected into the patient and, two hours later, a scan is performed.   Both normal and abnormal areas of its incorporation reflect sites of activity or inactivity (bone growth, bone reaction, bone destruction, bone death) . Infection, metabolic disturbances, tumor growth, injury and loss of blood supply are the most common causes for abnormal tracer concentrations. 
• visualize heart blood flow
• test kidney function
• diagnose cancer and the spread of cancer to different areas of the body
• diagnose lung issues, including respiratory problems
• identify thyroid problems
• locate abnormalities of the brain

Nuclear medicine can also be used for the following therapeutic purposes:

• treatment of hyperthyroidism and thyroid cancer
• treatment of tumors that have spread to the bone
• treatment of blood disorders
• treatment of lymphoma

What can I expect during a nuclear imaging session?

Nuclear imaging is usually a brief and relatively painless procedure. The testing is performed on an outpatient basis and begins with a technician or radiologist administering the radiotracer via injection or as a pill or gas. When the actual scanning will be performed depends on how long it takes for the radiotracer to accumulate in the area of the body being studied.

WBC Scans: Blood is drawn from the patient and an intravenous catheter secured. The white blood cells are separated from the rest of the blood sample and then mixed with a small amount of a radioactive material (a radioisotope) called indium-111. The cells with the radioactive material are considered "tagged." About 2 or 3 hours later, the tagged cells are returned to the patient through the same venous catheter. The tagged cells are then given time to gather in areas of inflammation or infection.

Approximately 6 to 24 hours later the patient is scanned on a special table. The scanner looks like an x-ray machine.  It detects the radiation given off by the radioactive white blood cells and a computer converts the detected radiation into an image that can be viewed on a screen or recorded on film.

The scan takes about 1 or 2 hours. The scanner is usually located in a hospital, but often the test can be performed on an outpatient basis. After the test is completed, no recovery time or special precautions are necessary.

Bone Scans: A nuclear bone scan is usually administered by a nuclear medicine technician with the help of the nursing staff.  They will simply inject a radioactive tracer substance into a vein in the patient’s arm. It is a simple, relatively painless procedure. The tracer substance is slightly radioactive, which will allow it to show up on the scanning device (camera) and help your doctor evaluate your condition. As the tracer substance circulates, it travels throughout the bloodstream, coming into contact with all the patient’s bones. It usually takes 2 to 3 hours for it to fully circulate and interact, where needed/indicated.  During this time, you can relax, read a book, leave the premises, etc.  

If you have any questions about nuclear imaging, consult your orthopedic surgeon or contact a local radiology center to learn more.