PET Scan

Overview

Positron Emission Tomography (PET) is a test that combines computed tomography (CT) and nuclear scanning. During a PET scan, a radioactive substance called a tracer is combined with a chemical (such as glucose); this mixture is generally injected into a vein (usually in the arm) but on occasion may be inhaled. The tracer emits tiny positively charged particles (positrons) that produce signals. The chemical substance and radioactive tracer chosen for the test vary according to which area of the body is being studied.

A 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.

Compared to CT scans and magnetic resonance imaging (MRI), PET produces less-detailed pictures of an organ.

A PET scan is often used to detect and evaluate cancer, such as of the lung or breast. It also can be used to evaluate the heart's metabolism and blood flow and examine brain function.