how to prepare for PET/CT
Positron emission tomography (or PET scan) is a test that combines computed tomography (CT) and nuclear scanning.
During a PET scan, a radioactive substance called a tracer (18F-FDG) is combined with a chemical substance (such as glucose) and is injected into a vein (usually in the arm). The tracer emits tiny, positively charged particles (called positrons) that produce signals. The chemical substance and radioactive tracer chosen for the test vary according to which area of the body will be studied.
A special camera records the tracer's signals as it travels through the body and collects in organs. A computer then converts the signals into three-dimensional images of the examined organ. The three-dimensional views can be produced from any angle and provide a clear view of an abnormality.
Unlike CT scans and magnetic resonance imaging (MRI), PET scanning doesn't produce as detailed a picture of the structure of an organ. Instead, PET scans provide information about an organ's function (metabolism). PET scanning is more expensive than CT scans and MRI and is not widely available at this time.
A PET scan is often used to evaluate tumors (such as of the lung or breast). It also can be used to evaluate the heart's metabolism and blood flow, detect certain types of tumors (such as lung and breast tumors), and examine brain function.