Isotope study

Injury	Disease	Nutrition	Poison

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Thyroid enlargement - scintiscan

Overview

Risks

Results

Isotope study

Definition:

Nuclear radiology is a sub-specialty of radiology in which radioisotopes (compounds containing radioactive forms of atoms) are introduced into the body for the purpose of imaging, evaluating organ function, or localizing disease or tumors.

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Unlike conventional or computed radiography (such as plain x-rays and CT scans) in which x-ray beams are generated within a machine and projected through the patient, in isotope studies the radiation (gamma rays) originates from within a radiopharmaceutical (material tagged with a radioisotope) in the body.

Special detector cameras are placed close against the area of interest for a period of time, and once enough gamma rays are "seen," a computer creates an image showing where the isotope localized within the organ or body.

Generally, nuclear medicine scans do not provide the level of anatomic detail seen on x-ray, ultrasound, CT, or MR images. However, correlation with other imaging, clinical information, and laboratory results helps identify and confirm disease.

See bone scan, nuclear ventriculography (MUGA or RNV), pulmonary ventilation/perfusion scan, thyroid scan, lung scan, and renal scan.

Alternative Names:

Scintillation; Radionuclide organ imaging; Radioisotope; Radioactive uptake; PET scan; Nuclear radiography; Nuclear medicine scan

How the test is performed:

A radioactive isotope needs to be introduced into the body. This may be done in several ways:

Through a needle into a vein (usually the inside of the elbow)
Through a catheter that is inserted into a vein or artery and is then guided to the organ being tested
Ingestion (for example, to test the thyroid, the patient swallows a pill containing radioactive iodine)
Subcutaneous injection (under the skin)
Collecting a patient's own blood from a vein, adding the radioisotope compound in a laboratory, and then injecting back into the patient

After a certain period of time has passed (ranging from a few hours to a day or more for different exams), you will be placed on a table (called a gantry) under the scanner, which may rotate around the body.

You must remain still to get accurate and useful images. For some tests, a counter is placed over the organ, and the amount of radioactivity or intensity of radioactivity is recorded.

A technician interprets the information as it is transmitted to the computer and can guide the camera to specific locations to improve the imaging.

How to prepare for the test: