[18F-FDG PET cerebral imaging for localizing epileptogenic foci and its relation to predicting operative outcome]

To find out the relationship between FDG PET image pattern and epileptogenic focus localization and predict prognosis by comparing pre- and post-surgical FDG images with operative effects.

72 patients with epilepsy who underwent surgery (49M, 23F, aged 24.3 years on average) were studied with pre-surgical FDG PET cerebral imaging and followed up (av. 15 months, 3-24 months) for assessment of seizure control. 20 of them were studied with post-surgical FDG PET. The accuracy of localization of epileptogenic foci of FDG PET was compared with that of VEEG and MRI. The relationship between pre- and post-surgical FDG metabolic image pattern and surgical outcome was evaluated.

(1) 71 patients showed pre-surgical interictal focal hypometabolism. 1 patient with continuous seizure showed ictal hypermetabolic focus. (2) FDG PET could localize the seizure foci in patients whose EEG showed bilateral or no definite epileptoform discharge. The rate of detection of epileptogenic foci with FDG PET was much higher than that with MRI. Since hypometabolic foci were non-specific, not all hypometabolic foci were epileptogenic. The correlation between postoperative FDG PET and surgical effect could help determine the nature of metabolic focus. (3) Hypometabolism of ipsilateral thalamus and/or contralateral cerebellum with temporal lobe lesion was secondary functional change. (4) The patternization of cerebral images was helpful to surgical planning and helped predict operative outcome.

Comparison of pre-surgical with post-surgical FDG PET images help determine the nature of hypometabolic foci. The patternization of FDG PET images help the surgeon select patients, plan type of operation and predict surgical effect.