Glucose Metabolic Profile by Visual Assessment Combined with Statistical Parametric Mapping Analysis in Pediatric Patients with Epilepsy

PET with F-18-FDG has been used for presurgical localization of epileptogenic foci; however, in nonsurgical patients, the correlation between cerebral glucose metabolism and clinical severity has not been fully understood. The aim of this study was to evaluate the glucose metabolic profile using F-18-FDG PET/CT imaging in patients with epilepsy. Methods: One hundred pediatric epilepsy patients who underwent F-18-FDG PET/CT, MRI, and electroencephalography examinations were included. Fifteen age-matched controls were also included. F-18-FDG PET images were analyzed by visual assessment combined with statistical parametric mapping (SPM) analysis. The absolute asymmetry index (jAIj) was calculated in patients with regional abnormal glucose metabolism. Results: Visual assessment combined with SPM analysis of F-18-FDG PET images detected more patients with abnormal glucose metabolism than visual assessment only. The jAIj significantly positively correlated with seizure frequency (P < 0.01) but negatively correlated with the time since last seizure (P < 0.01) in patients with abnormal glucose metabolism. The only significant contributing variable to the vertical bar AI vertical bar was the time since last seizure, in patients both with hypometabolism (P = 0.001) and with hypermetabolism (P = 0.005). For patients with either hypometabolism (P < 0.01) or hypermetabolism (P = 0.209), higher jAIj values were found in those with drug resistance than with seizure remission. In the post-1-y follow-up PET studies, a significant change of jAIj (%) was found in patients with clinical improvement compared with those with persistence or progression (P < 0.01). Conclusion: F-18-FDG PET imaging with visual assessment combined with SPM analysis could provide cerebral glucose metabolic profiles in nonsurgical epilepsy patients. jAIj might be used for evaluation of clinical severity and progress in these patients. Patients with a prolonged period of seizure freedom may have more subtle (or no) metabolic abnormalities on PET. The clinical value of PET might be enhanced by timing the scan closer to clinical seizures.