title: 18FDG-PET in different subtypes of temporal lobe epilepsy: SEEG validation and predictive value.
abstract: OBJECTIVE
  The objective of the study was to characterize interictal 18-fluorodeoxyglucose-positron emission tomography ((18) FDG-PET) whole-brain voxel-based metabolic patterns among distinct subtypes of temporal lobe epilepsy (TLE), as defined by stereo-electroencephalography (SEEG) and to determine predictive value of PET result on postoperative outcome.
  
  
  METHODS
  Fifty-four consecutive patients with pharmacoresistant TLE were enrolled retrospectively after a comprehensive presurgical evaluation. This evaluation defined: 7 lateral TLE, 17 mesial TLE, 14 "plus" TLE, and 16 bilateral TLE. Whole-brain voxel-based brain metabolism was studied in each group of patients, in comparison to 23 healthy subjects, and individual classification was evaluated by cross-validation using the found clusters. An (18) FDG-PET index was moreover calculated for each patient, based on the individual Z-score of the most significant cluster extracted on the comparison between patients' subgroup and healthy subjects. Logistic regression analysis was used to estimate factors associated with postoperative outcome (Engel's classes III-IV vs. I-II), including age, gender, disease duration, seizure frequency, as well as magnetic resonance imaging (MRI) and PET findings.
  
  
  RESULTS
  Different patterns of hypometabolism were found inside and outside the epileptogenic zone, among patients with distinct subgroups of TLE, in comparison to healthy subjects (p < 0.001, corrected for the cluster). At individual level, cross-validation showed satisfactory discrimination between the four groups with 71.4-88.2% overall accuracy. Multivariate analysis shows that (18) FDG-PET index was the only significant predictor of postoperative outcome to distinguish between Engel's classes I-II and III-IV (p = 0.037).
  
  
  CONCLUSIONS
  Overall, this whole-brain voxel-based analysis validates specific patterns of hypometabolism, inside and outside the EZ, in distinct subgroups of patients with TLE, as defined by SEEG gold standard, and in relation with postoperative outcome.
authors.affiliation: Nuclear Medicine Department, Timone Hospital, APHM, Marseille, France; CERIMED, Aix-Marseille University, Marseille, France; CNRS, UMR7289, INT, Aix-Marseille University, Marseille, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Guedj
authors.forename: Francesca
authors.initials: F
authors.lastname: Bonini
authors.forename: Martine
authors.initials: M
authors.lastname: Gavaret
authors.forename: Agnès
authors.initials: A
authors.lastname: Trébuchon
authors.forename: Sandrine
authors.initials: S
authors.lastname: Aubert
authors.forename: Mohamed
authors.initials: M
authors.lastname: Boucekine
authors.forename: Laurent
authors.initials: L
authors.lastname: Boyer
authors.forename: Romain
authors.initials: R
authors.lastname: Carron
authors.forename: Aileen
authors.initials: A
authors.lastname: McGonigal
authors.forename: Fabrice
authors.initials: F
authors.lastname: Bartolomei
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D058256:Brain Waves / Q000502:physiology; D016002:Discriminant Analysis; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000145:classification / Q000175:diagnosis / Q000000981:diagnostic imaging; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: Epileptogenic zone; Positron emission tomography; Postoperative outcome; Statistical parametric mapping; Stereoelectroencephalography; Temporal lobe epilepsy