Positron emission tomography, also called PET imaging or a PET scan, is a diagnostic examination that involves the acquisition of physiologic images based on the detection of positrons. Positrons are tiny particles emitted from a radioactive substance administered to the patient. The subsequent views of the human body developed by this technique are used to evaluate a variety of diseases.

    PET scans of the brain are used to evaluate patients who have memory disorders of an undetermined cause; who have suspected or proven brain tumors; or who have seizure disorders that are not responsive to medical therapy and, therefore, are candidates for surgery.