What is Nuclear Medicine?
A nuclear medicine procedure is sometimes described as an “inside-out” x-ray because it records radiation emitting from the patient’s body rather than radiation that is directed through the patient’s body. Nuclear medicine procedures use small amounts of radioactive materials, called radiopharmaceuticals, to create images of anatomy. Radiopharmaceuticals are substances that are attracted to speciﬁc organs, bones, or tissues. They are introduced to the patient’s body by injection, swallowing, or inhalation. As the radiopharmaceutical travels through the body, it produces radioactive emissions. A special type of camera detects these emissions in the organ, bone or tissue being imaged and then records the information on a computer screen or on ﬁlm.
Nuclear medicine is unique because it documents function as well as structure. For example, nuclear medicine allows physicians to see how a kidney is functioning, not just what it looks like. Most other diagnostic imaging tests, in comparison, reveal only structure. Nuclear medicine procedures are performed to assess the function of nearly every organ. Common nuclear medicine procedures include thyroid studies, brain scans, bone scans, lung scans, cardiac stress tests, and liver and gallbladder procedures.
Although nuclear medicine is primarily used for diagnosis, it can be used to treat disease as well.
During your examination
For most nuclear medicine examinations, the patient is positioned on a scanning table underneath a scintillation or gamma camera. A radiopharmaceutical then is administered intravenously, orally or through inhalation. It travels through the patient’s bloodstream to a speciﬁc area where it selectively accumulates. The camera then detects and records the radioactive emissions from the patient’s body.
For some nuclear medicine studies, imaging takes place immediately. For others, images are taken an hour, two hours, or even the following day after administration of the radiopharmaceutical. In most cases, the patient is permitted to leave the facility and return later for the imaging procedure.
Most nuclear medicine procedures require several different images from different angles, and the technologist may ask you to change positions during the examination. You will need to lie still during each scan.
A thyroid uptake study shows how well the thyroid gland is functioning. If the radiopharmaceutical is administered orally, you will be asked to return the next day for scanning. If it is injected, the scans are performed immediately. You may be asked to avoid all foods and medicines that contain iodine for several days before the test, because they can distort test results.
Lung scans usually are performed to detect blood clots in the lungs.
For gallbladder imaging, images usually are taken within an hour of administration of a radiopharmaceutical. For imaging requiring an ejection fraction, you will be asked to drink a high caloric liquid, with additional imaging taken immediately afterwards. The study can detect gallbladder disease and reveal how well the liver is functioning.
Bone scans detect fractures, tumors, and infections. Imaging may be performed immediately, although it is usually performed several hours after the radiopharmaceutical is injected. If your entire body needs to be scanned, the imaging portion of the procedure can last two to four hours.
After your examination
After the examination, 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. Your physician will then advise you of the results and discuss what further procedures, if any, are needed.
The radiation that you 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. In general, the radiopharmaceutical administered during the examination will be eliminated naturally from your body in one or two days. Drinking ﬂuid will help clear the radiopharmaceuticals from your system more quickly.