Nuclear medicine/PET (positron emission tomography) is specialty of its own as well as a subspecialty within the field of radiology. Nuclear medicine imaging differs from most other types of imaging in that the tests mainly show the physiological and metabolic processes of the body as opposed to the anatomy. Nuclear medicine, which produces images without invasive techniques, is often used with other types of imaging and tests.
Froedtert & The Medical College of Wisconsin are unique in having three full time, board-certified nuclear medicine physicians.
Nuclear medicine/PET provides information about the structure and function of virtually every major organ system within the body. It is this ability to characterize and quantify organ function that separates nuclear medicine and PET/CT from other types of imaging.
In nuclear medicine and PET/CT diagnosis, a tiny amount of a radioactive substance is given to a patient, and the radiation emitted is measured. Nuclear medicine is also an important tool for treating certain diseases such as hyperthyroidism (overactive thyroid) as well as thyroid cancer, lymphoma and other cancers.
Nuclear medicine images are based on the detection of energy emitted from a short-acting radioactive substance (tracer) given to the patient, usually through a vein (IV) or by mouth. In general, the small amount of radiation given to the patient is similar to or less than that of a standard X-ray exam. The tracer disappears from the body within a few days.
The tracer attaches to or is absorbed by the tissues in the body. Certain tracers accumulate more in certain organs. The type of radioactive tracer used depends on the part of the body being examined. For example, to evaluate bones, a tracer is used that is absorbed by new bone cells. To image blood flow and heart function, a specific tracer is used that reflects blood flow.
Depending on the type of tracer used, it may take 30 minutes, a few hours, or a few days for the tracer to accumulate in the appropriate organ. During longer periods, patients are able to resume their normal activities after receiving the tracer and return later for the imaging.
A gamma camera or PET/CT scanner (special detection devices) trace the radioactive substances in the body to see where they concentrate. The gamma camera can acquire two-dimensional (planar) images or three-dimensional images (in SPECT imaging). Computers create the final images.
Nuclear medicine is used to diagnose a wide range of disorders such as abnormal tissue (cancer), problems with heart function, blood flow in the brain, infections and how the body responds to disease. Nuclear medicine can also used to evaluate kidney function, thyroid function, lung problems, bleeding in the bowels, a poorly functioning gallbladder, bone fractures and arthritis.
The two major types of technology used in nuclear imaging are SPECT scanners and PET/CT scanners.
Bone density scanning is another type of nuclear medicine test done to assess the strength of the bones and the probability of fracture in people at risk for osteoporosis.
Author: Marla Fraunfelder
Last Review Date: Aug. 10, 2007