During the intraictal phase, FDG uptake in epileptic foci shows what kind of change?

During the intraictal phase of epilepsy, there is a distinct increase in cerebral metabolism within the epileptic foci. This is often reflected in the uptake of fluorodeoxyglucose (FDG), a radiotracer used in PET imaging. During an ictal event, which is characterized by active seizure activity, the brain regions involved in the seizure exhibit heightened metabolic activity due to the increased neuronal demand for glucose. This heightened activity is associated with increased perfusion; as neurons fire more during seizures, they consume more glucose, leading to higher FDG uptake.

The metabolism of the affected brain regions not only increases because of the greater energy demands, but this increase is also visible on the PET scan as a higher signal where the FDG accumulates. This is why during the intraictal phase, enhanced FDG uptake corresponds with increased perfusion, distinguishing the affected areas from those that are functioning normally, where perfusion and metabolic demands do not reach these elevated levels.

Therefore, the correct interpretation of FDG uptake in epileptic foci during the intraictal phase is that it demonstrates increased uptake correlated with heightened perfusion and metabolic activity.