PET/CT Frequently Asked Questions

Q. How is a PET scan performed?

A. Performing an actual PET scan involves having the patient recline on a table that slides into the middle of an “open-air” scanner. Within the scanner are rings of detectors containing special crystals that produce electronic signals when struck by radiation. The information obtained is then reconstructed into cross-sectional images. During PET/CT, an abbreviated CT examination is performed simultaneously with the PET study, improving the accuracy. The examination itself takes approximately 25 minutes.

Q. What is the injection?

A. The patient’s vein is injected with FDG fluorodeoxyglucose, a sugar tagged with a trace dose of radioactive biochemical (radiopharmaceutical) material approximately 45 minutes before the PET scan. The scanner’s electronics record detected positron rays and maps an image of the area where the radiopharmaceutical is concentrated. Since the radiopharmaceutical is comprised of a chemical commonly processed by the body’s metabolism, like sugar, PET enables the physician to detect the location of the metabolic process.  As an example, a PET study, using fluro-deoxyglucose (FDG) as the radioisotope, will demonstrate where increased glucose uptake is occurring, thereby detecting  certain types of hypermetabolic tumor spread, often even before the spread is visible on standard CT or MRI exams.