title: Alpha-methyl-L-tryptophan PET detects epileptogenic cortex in children with intractable epilepsy.
abstract: BACKGROUND
  In children with tuberous sclerosis, the PET tracer alpha[11C]methyl-L-tryptophan (AMT) has been shown to be selectively taken up by epileptogenic tubers, thus allowing differentiation from nonepileptogenic tubers in the interictal state.
  
  
  OBJECTIVE
  To determine whether cortical areas showing increased AMT uptake in children without tuberous sclerosis complex with intractable neocortical epilepsy indicate the epileptogenic zone, and to assess the relative contributions of AMT and 2-deoxy-2[18F]fluoro-D-glucose (FDG) PET abnormalities to the localization of epileptogenic cortical regions.
  
  
  METHODS
  Areas of increased AMT and decreased FDG uptake were marked objectively as regions with abnormal asymmetry using an in-house written software in 27 children who underwent comprehensive evaluation for resective epilepsy surgery. The marked PET abnormalities were compared to the locations of scalp and subdural EEG epileptiform abnormalities, as well as histology and surgical outcome.
  
  
  RESULTS
  Focal cortical increases of AMT uptake were found in 15 patients. The lobar sensitivity (39.0%) of AMT PET for seizure onset was lower, but its specificity (100%) was higher (p < 0.0001) than that of hypometabolism on FDG PET (sensitivity 73.2%, specificity 62.7%). AMT PET abnormalities were smaller than corresponding FDG PET hypometabolic regions (p = 0.002), and increased AMT uptake occurred in two patients with nonlocalizing FDG PET. Histologically verified cortical developmental malformations were associated with increased AMT uptake (p = 0.044). Subdural electrodes adjacent to the area of increased AMT uptake were most often involved in seizure onset.
  
  
  CONCLUSIONS
  Focal increase of cortical AMT uptake in children is less sensitive but more specific for the lobe of seizure onset than corresponding FDG PET hypometabolism, and it is often associated with epileptogenic cortical developmental malformations. AMT PET can assist placement of subdural electrodes even when MRI and FDG PET fail to provide adequate localizing information. Cortical areas adjacent to increased AMT uptake should be carefully addressed by intracranial EEG because these regions often show a high degree of epileptogenicity.
authors.affiliation: Department of Pediatrics, Children's Hospital of Michigan, Detroit Medical Center, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: C
authors.initials: C
authors.lastname: Juhász
authors.forename: D C
authors.initials: DC
authors.lastname: Chugani
authors.forename: O
authors.initials: O
authors.lastname: Muzik
authors.forename: A
authors.initials: A
authors.lastname: Shah
authors.forename: E
authors.initials: E
authors.lastname: Asano
authors.forename: T J
authors.initials: TJ
authors.lastname: Mangner
authors.forename: P K
authors.initials: PK
authors.lastname: Chakraborty
authors.forename: S
authors.initials: S
authors.lastname: Sood
authors.forename: H T
authors.initials: HT
authors.lastname: Chugani
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography; D004734:Energy Metabolism; D004827:Epilepsy / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D019579:Neocortex / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D012701:Serotonin / Q000378:metabolism; D014055:Tomography, Emission-Computed; D016896:Treatment Outcome; D014364:Tryptophan / Q000031:analogs & derivatives*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; C020774:alpha-methyltryptophan; D012701:Serotonin; D014364:Tryptophan