A PET scan uses a radionuclide (18fluoro-deoxy-glucose; FDG) to investigate the metabolic profile of the whole brain; areas of focal epilepsy exhibit reduced metabolism that can be visually identified. PET scans can be particularly useful in patients who have no visible MRI lesions to identify epileptogenic brain areas, or to grade disease within brain regions when there is more than one brain MRI lesion.
Information for patients
A PET scan may be requested as part of workup for your seizure disorder, especially if epilepsy surgery is being considered for you. PET scans take place following an injection of a radioactive substance into your bloodstream, that travels to the brain and identifies areas of brain that are ‘working’ (metabolizing glucose) as normal, or abnormally. In this way, brain regions that are not metabolically normal are picked up on the scan as ‘cold’ (or occasionally, ‘hot’) regions. Such information can be valuable in diagnosing the brain region producing seizures, and can influence the type of surgery that is offered. Importantly, PET scans can sometimes give information when an MRI scan does not, so both types of scans are important for certain patients.