P.E.T.

Found this at www.radiologyinfo.org :

What is Positron Emission Tomography (PET) Scanning

Sample image obtained using a combination of PET and CT imaging technology.
Positron emission tomography, also called PET imaging or a PET scan, is a type of nuclear medicine imaging.
Nuclear medicine is a subspecialty within the field of radiology that uses very small amounts of radioactive material to diagnose or treat disease and other abnormalities within the body.
Nuclear medicine imaging procedures are noninvasive and usually painless medical tests that help physicians diagnose medical conditions. These imaging scans use radioactive materials called a radiopharmaceutical or radiotracer.
Depending on the type of nuclear medicine exam you are undergoing, the radiotracer is injected into a vein, swallowed by mouth or inhaled as a gas and eventually collects in the area of your body being examined, where it gives off energy in the form of gamma rays. This energy is detected by a device called a gamma camera, a (positron emission tomography) PET scanner and/or probe. These devices work together with a computer to measure the amount of radiotracer absorbed by your body and to produce special pictures offering details on both the structure and function of organs and other internal body parts.
In some centers, nuclear medicine images can be superimposed with computed tomography (CT) or magnetic resonance imaging (MRI) to produce special views, a practice known as image fusion or co-registration. These views allow the information from two different studies to be correlated and interpreted on one image, leading to more precise information and accurate diagnoses.
A PET scan measures important body functions, such as blood flow, oxygen use, and sugar (glucose) metabolism, to help doctors evaluate how well organs and tissues are functioning.