Abstracts

To determine the sensitivity and specificity of alpha[11C]methyl-L-tryptophan (AMT) PET in identifying the epileptic focus in children with intractable neocortical epilepsy associated with and without malformations of cortical development (MCDs)., Seventy children with medically refractory epilepsy were divided into classified into lesional (MCDs) group (n = 26) and non-lesional group (n = 44) based upon MRI and neuropathological diagnoses. Focal increased AMT uptake was determined by asymmetry index with measurement of AMT uptake asymmetries of small homotopic cortical regions. The incidence and magnitude of focal increased AMT uptake were examined and compared between the lesional and non-lesional group., The lobar specificity of AMT PET for seizure onset was equally high in both groups (97% vs 100%), while its sensitivity was significantly higher in the lesional group (47%) than in the non-lesional group (29%) (p = 0.047). Focal increased AMT uptake was found in 27% of the non-localizing MRI group. The incidence of the focal increased AMT uptake was significantly higher in the lesional group (58%) than the non-lesional group (19%)(p [lt] 0.01). Patients with focal cortical dysplasia had a significantly higher value of the asymmetry index (18.5 [plusmn] 7.1%) in comparison with the non-lesional patients (12.1 [plusmn] 3.1%) (p = 0.04) and with those with other types of MCDs (12.1 [plusmn] 2.8%) (p = 0.03)., Patients with MCDs showed a significantly higher incidence of focal cortical AMT PET abnormalities, with a greater magnitude of increased AMT uptake being identified in patients with focal cortical dysplasia. These result suggests that altered tryptophan metabolism is more frequent and pronounced in focal cortical dysplasia compared to other types of MCDs.,