title: Can we increase the yield of FDG-PET in the preoperative work-up for epilepsy surgery?
abstract: OBJECTIVE
  [(18)F] Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) is a semi-invasive, interictal method of localization of hypometabolic epileptic foci. FDG-PET can be useful in the clinical work-up prior to epilepsy surgery, especially in equivocal cases. We investigated whether we could increase the yield of presurgical FDG-PET in patients with difficult epilepsy requiring chronic subdural electrocorticography (ECoG).
  
  
  METHODS
  We retrospectively studied patients with refractory focal epilepsy in whom there was uncertainty about the focus localization and who underwent FDG-PET and ECoG. Two experts (epileptologist and nuclear medicine radiologist) together systematically re-assessed the scans visually (PETRE), blinded to their initial reports. Scans were also re-analyzed by comparing them to a normal control dataset with Statistical Parametric Mapping (SPM), using a liberal (PETSPM1), and strict (PETSPM2) statistical threshold. Regions with hypometabolism and regions containing the seizure onset zone (SOZ) in ECoG were marked as positive anatomical regions (PARs). We compared the concordance of these PARs for the different PET re-assessments. We calculated the sensitivity, specificity and accuracy of the PET results for the SOZ. The added value of the re-assessments was evaluated with emphasis on scans initially reported as negative.
  
  
  RESULTS
  41 Patients (63% extra-temporal) were included. PETRE identified the SOZ best, with a sensitivity of 62% and specificity of 93%. PETSPM1 had a sensitivity of 62% and specificity 69%, for PETSPM2 this was 35% and 85% respectively. The overlap between PETRE vs. PETSPM1 and vs. PETSPM2 was 71% and 37%. Visual re-assessment and PETSPM1 identified the SOZ in four out of five scans that were initially reported as negative.
  
  
  CONCLUSIONS
  Pre-surgical re-assessment of PET scans is worthwhile in epilepsy patients who undergo ECoG, especially when results were reported as negative before. Visual re-assessment itself has a higher combined specificity, sensitivity and accuracy than SPM analysis alone. SPM analysis could be used as a guide for visual (re-)assessment, because of its high sensitivity.
authors.affiliation: Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands. Electronic address: m.a.vanhetklooster-2@umcutrecht.nl.
authors.forename: Maryse A
authors.initials: MA
authors.lastname: van't Klooster
authors.affiliation: Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Geertjan
authors.initials: G
authors.lastname: Huiskamp
authors.affiliation: Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands; SEIN - Stichting Epilepsie Instellingen Nederland, Heemstede, The Netherlands.
authors.forename: Maeike
authors.initials: M
authors.lastname: Zijlmans
authors.affiliation: SEIN - Stichting Epilepsie Instellingen Nederland, Heemstede, The Netherlands.
authors.forename: René M Chr
authors.initials: RM
authors.lastname: Debets
authors.affiliation: Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Emile F I
authors.initials: EF
authors.lastname: Comans
authors.affiliation: CERMEP - Imagerie du Vivant, Bron, France; Translational and Integrative Group in Epilepsy (TIGER), Lyon Neuroscience Research Center, INSERM U1028 - CNRS UMR5292, Bron, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Bouvard
authors.affiliation: Institute for Child and Adolescent with Epilepsy (IDEE), Hospices Civils de Lyon, Bron, France; Translational and Integrative Group in Epilepsy (TIGER), Lyon Neuroscience Research Center, INSERM U1028 - CNRS UMR5292, Bron, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Ryvlin
authors.affiliation: Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Frans S S
authors.initials: FS
authors.lastname: Leijten
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D002648:Child; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods*; D004828:Epilepsies, Partial / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011300:Preoperative Care / Q000379:methods; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012640:Seizures / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: Cortical dysplasia; Electrocorticography; Epilepsy surgery; Positron emission tomography