PET CT Scanning

Positron Emission Tomography (PET) is a nuclear medicine imaging technique which produces a 3D image or map of functional processes in the body: PET scans are done in conjunction with CT or MRI scans, the combination giving both anatomic and metabolic information (i.e., what the structure is and how it is behaving chemically).

To conduct the scan, a short-lived radioactive tracer isotope is injected into the blood stream. This small amount of radioactivity is not harmful to the patient.

The tracer used (fluorodeoxyglucose, known as FDG) takes around an hour to become concentrated in areas of interest within the body. During this time, the patient must remain quiet and calm in a darkened room to allow the FDG to distribute through the body to give the most accurate results.

After this period, known as the "uptake time", the patient will be moved gradually through the scanner to produce a series of images. The whole process can take two to three hours to complete. The radioactive isotope passes easily through the system via normal bodily functions (the majority is excreted via the bladder so, after the scan, the patient will be advised to drink extra fluids).

PET CT scans are most useful in assessing and identifying some cancers, and in diagnosing blood vessel disease and brain disorders (such as dementia).