Positron emission tomography (PET) scan 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.
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.
Compared to CT scans and magnetic resonance imaging (MRI), the
pictures from a PET scan do not show as much detail.
