PET/CT is a diagnostic procedure that combines the principles of two imaging tools, the positron emission tomography (PET) and computed topography (CT). PET administers a radioactive substance into the body, which is taken up by the diseased region and detected by a camera or imaging device. It can identify changes at a cellular level, and measures functions such as blood flow, oxygen use and sugar metabolism. A CT scan uses X-rays to produce multiple detailed cross-sectional images of the structures inside the body. In a PET/CT, the PET and CT images are fused by a computer so that both results can be correlated, and a complete overview of the structure and activities in a part of the body can be understood. It enables your doctor to identify areas of abnormal function and pinpoint their location.
PET/CT scans are used to detect and monitor tumors, assess the structure and function of the heart, brain and other structures of the body, and evaluate the effectiveness of a treatment. PET and CT scans may either be performed one after the other or simultaneously using a special equipment.
You are instructed to stop eating food several hours before the test and encouraged to drink plenty of water.
The PET/CT machines are similar having a short tunnel through which you enter while lying on a bed. For the PET scan, a radioactive substance or tracer is swallowed, injected or inhaled, and accumulates in the organ of interest. Its emissions are perceived by special detectors and used to create pictures and provide molecular information. During the CT, a contrast dye is injected, the scanner spins around you while you lie on and exam table, and multiple X-rays are obtained and assimilated by a computer. You must remain still during the entire procedure and may be asked to hold your breath to avoid blurring of images. The entire procedure takes about 30 minutes. Following the procedure, you are encouraged to drink plenty of fluids to flush out the radioactive tracer.