title: Ictal SPECT in neocortical epilepsies: clinical usefulness and factors affecting the pattern of hyperperfusion.
abstract: BACKGROUND
  The aims of this analysis were to: (1) determine the value of ictal SPECT in the localization of neocortical epileptogenic foci, (2) evaluate the relationships between the results of ictal SPECT and other potential affecting factors, and (3) compare traditional visual analysis and the subtraction method.
  
  
  METHODS
  We retrospectively analyzed 81 consecutive patients with neocortical epilepsy who underwent epilepsy surgery and achieved a favourable surgical outcome, including 36 patients with normal MRI. Side-by-side visual analysis and subtraction images were classified as correctly localizing,correctly lateralizing, or non-localizing/non-lateralizing images according to the resected lobe.
  
  
  RESULTS
  Side-by-side visual analysis and subtraction SPECT correctly localized the epileptogenic lobe in 58.9% and 63.0% of patients, respectively. The two methods were complementary and the diagnostic sensitivity of ictal SPECT using the two methods was 79.0%. Ictal SPECT using the visual method correctly localized the epileptogenic lobe more frequently in patients with a localizing pattern of ictal scalp EEG at the time of radioligand injection. When using subtraction images, an injection delay of less than 20 s after seizure onset was significantly correlated with correct localization. The subtraction method was superior to the visual method for localizing frontal lobe epilepsy (FLE) and parietal lobe epilepsy (PLE), and in patients with non-localizing/non-lateralizing EEG at onset.
  
  
  CONCLUSIONS
  Ictal SPECT analyses using visual and subtraction methods are useful and complementary for the localization of the epileptogenic foci of neocortical epilepsy. Early radioligand injection and ictal EEG patterns are related to ictal SPECT localization. The subtraction method may be more useful in some epileptic syndromes.
authors.affiliation: Department of Neurology, Seoul National University Hospital, 28, Yongon-Dong, Jongno-Gu, 100-744, Seoul, South Korea. sangunlee@dreamwiz.com
authors.forename: Sang Kun
authors.initials: SK
authors.lastname: Lee
authors.forename: Seo-Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Chang-Ho
authors.initials: CH
authors.lastname: Yun
authors.forename: Ho-Young
authors.initials: HY
authors.lastname: Lee
authors.forename: Jae-Sung
authors.initials: JS
authors.lastname: Lee
authors.forename: Dong-Soo
authors.initials: DS
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D002540:Cerebral Cortex; D002648:Child; D004569:Electroencephalography; D004827:Epilepsy / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D019579:Neocortex / Q000000981:diagnostic imaging*; D009778:Occipital Lobe / Q000000981:diagnostic imaging; D010296:Parietal Lobe / Q000000981:diagnostic imaging; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D013702:Temporal Lobe / Q000000981:diagnostic imaging; D015899:Tomography, Emission-Computed, Single-Photon