[Neuroimaging for surgical treatment of epilepsy]

Imaging of interictal 18F-FDG PET and ictal SPECT is useful for identifying regions of seizure in epilepsy. Epileptic foci usually show decreased and increased flow/metabolism in the interictal and ictal phase respectively. A fusion technique of high resolution PET and MRI has become indispensable to preoperative evaluation for epileptic surgery. Subtraction ictal SPECT coregistered to MRI (SISCOM) is also an useful technique for localizing significant flow increase in the focus. Central type benzodiazepine receptor imaging using 11C-flumazenil PET or 123I-iomazenil SPECT is an alternative and sensitive technique for localizing epileptogenic regions. This receptor imaging delineates epileptic foci more precisely than 18F-FDG PET. There has been considerable interest in the role that functional magnetic resonance imaging (fMRI) may play in the assessment of patients with epilepsy. The application of fMRI paradigms used in cognitive neuroscience to patients with epilepsy is complicated. Although fMRI is increasingly being used clinically to establish language dominance, further work is required to localize accurately those specific language functions that are most at risk following surgery. Memory paradigms are not yet validated for use in surgical planning, although methodological and technical advances should make this possible in the near future.