Positron Emission Tomography (PET):

Positron Emission Tomography (PET) is a technique for measuring concentrations of positron-emitting radioisotopes within tissues of living subjects.  PET imaging can be used to map biological function of an organ.  It can detect subtle metabolic changes, ascertain whether a disease is active or inactive, and to help determine if a tumor is malignant or benign.  PET scanning may be used to stage certain cancer types. 

PET can be broken down into several stages: (1) the labeling of a selected compound with a positron- emitting radionuclide, (2) the administration of the compound to the patient to be studied, (3) imaging of the distribution of positron activity as a function of time by emission tomography, and (4) evaluation of component distribution and activity in the tissue. 

A PET Scan is an expensive test.  PET facilities require sophisticated computer equipment, a cyclotron, and highly trained specialists.  A cyclotron is an accelerator that propels charged particles, referred to as protons using alternating voltage in a magnetic field.

The test requires the injection of a radionuclide pharmaceutical (known as a “tracerâ€?) specific to the function or category of metabolism to be investigated.  Shortly after injection of the tracer, it accumulates in specific bodily regions.  To perform the study, the patient lies on a scanning table while a ring-shaped machine is properly positioned over the target area.  Sensors pick up gamma rays emitted from internal body tissues.  The computer analyzes this data to produce cross-sectional images on film and/or on a video monitor.  The images are typically color coded according to the concentration of the tracer.