Positron emission tomography (PET) scan in epilepsy.

ABSTRACT

Positron Emission Tomography (PET) has an advantage in localizing epileptogenic zones for successful surgery in several epileptic syndromes. Among the most radiopharmaceutical used in PET studies in epilepsy are [18F] fluorodeoxyglucose (FDG) and [11C]flumazenil (FMZ). Unilateral temporal hypometabolism (UTH) seen in FDGPET was shown to correlate well with ictal EEG origins in 60-90 % of temporal lobe epilepsy (TLE) patients. PET aids in surgical decision-making in TLE patients with discordant data from initial presurgical evaluation, in bitemporal disease and in nonlesional TLE. However, PET adds little in lesional TLE with congruent data. The extent of glucose hypometabolic area was shown to correlate with post-operative outcomes. PET may reduce the need for invasive EEG in bitemporal epilepsy. Abnormal FMZ binding has been proposed to guide the location of subdural electrode placement in extratemporal epilepsy (ETE). FMZ-PET and FDG-PET were shown to be sensitive in visualizing areas of cortical dysgenesis. Focal FDG-PET abnormality was demonstrated in 20 % of children with West’s syndrome and has provided a revolutionary approach for surgical treatment. Resection of the focal hypometabolism has rendered good control of infantile spasms and restoration of developmental delay. PET use of alpha-[11C] methyl-L-tryptophan (AMT), a serotonin precursor, has been shown to selectively localize epileptogenic tuber in the tuberous sclerosis complex as well as in identifying epileptic residual tissue following surgical failure. PET has potential in determining eloquent brain areas and in studying mechanisms of epilepsy. In epilepsy surgery, PET can be used with worthwhile cost-benefit even in a country with limited resources.