Comparison of various imaging modalities in localization of epileptogenic lesion using epilepsy surgery outcome in pediatric patients

PURPOSE: We employed the results of imaging modalities from pediatric patients who received successful epilepsy surgery to determine the accuracy of each imaging tool in identifying epileptic zones in youngsters.

METHODS: All Engel class I pediatric patients who received epilepsy surgery between October 2003 and April 2008 were selected. Their pathology, EEG, MRI, PET, and subtraction ictal SPECT coregistered to MRI (SISCOM) results were compared for accuracy in locating the epileptic foci, defined as "area that resulted in seizure ablation after resection".

RESULTS: Forty-two patients were enrolled (23 temporal lobectomy, 19 extratemporal resections). MRI showed concordance in 84.2% of extratemporal cases, all of which had precise localization of lesions. In temporal cases, lateralization was 91.3% and localization was 82.6%. PET showed a concordance rate of 95.5% and localization was 72.7% for temporal lesions. For extratemporal lesions, concordance was only 68.4%. SISCOM showed concordance in 100% of temporal and 92.3% of extratemporal cases, with localization in 66.7% of temporal and 84.6% of extratemporal cases. Most temporal lobe cases had hippocampal sclerosis, and cortical dysplasia was observed in extratemporal cases.

DISCUSSION: MRI was invariably reliable in all cases. PET results were as reliable in lateralizing the temporal epileptic area, while its efficacy was lower for extratemporal cases. SISCOM effectively localized lesions in extratemporal cases, but its efficacy was lower in temporal lesions. In cases of conflicting pre-surgical results, MRI, with supplementary data from PET, helped to establish correct decisions in temporal epilepsies, while utilization of SISCOM and MRI data is advised for extratemporal cases.