Inclusion Criteria:  (a) age between 6 and 18 years; (b) 18F-FDG PET examination more than 48 h since the last seizure, (c) no structural abnormalities associated with epilepsy detected on routine MRI  Exclusion Criteria:  (a) any history of other neurological or psychiatric disorders; (b) pre-scan plasma glucose level > 120 mg/dl before 18F-FDG PET/CT examination;(c) any contraindications for MRI examination ; (d) head movement (translation > 3 mm or rotation > 3 degree ) during MRI examination