title: Localization of the epileptogenic zone by ictal and interictal SPECT with 99mTc-ethyl cysteinate dimer in patients with medically refractory epilepsy.
abstract: OBJECTIVE
  To evaluate the accuracy, feasibility and clinical value of both ictal and interictal 99mTc-ethyl cysteinate dimer (ECD) single photon emission computed tomography (SPECT) in patients with medically refractory epilepsy.
  
  
  METHODS
  The study included 75 consecutive patients, 48 with temporal lobe epilepsy (TLE group), and 27 with extratemporal epilepsy (ExT group). The accuracy of SPECT was analyzed considering the final diagnosis reached by convergence of clinical, electrophysiologic, structural, pathologic and outcome data.
  
  
  RESULTS
  Ictal SPECT correctly identified the epileptogenic zone in 21 (91.3%) of 23 patients, whereas interictal SPECTs could correctly identify the epileptogenic zone in only 41 (62.1%) of 66 patients (chi2 = 5.56, df = 1, p < 0.05). Results were similar when the two study groups were analyzed separately. Moreover, ictal studies had significantly higher specificity (91.3 vs. 60.6%) and positive predictive value (91.3 vs. 66.2%) than interictal studies for the whole series of patients. Considering all tools used in the preoperative workup of these patients, ictal SPECT significantly contributed to the final topographic diagnosis in seven of 14 patients from TLE group and in six of nine patients from the ExT group. In these patients, ictal SPECT either obviated the need for invasive EEG or helped to define where to concentrate the efforts of invasive investigation.
  
  
  CONCLUSIONS
  These data demonstrate that ictal SPECT can be easily achieved by using 99mTc-ECD and can accurately localize the epileptogenic zone in both temporal and extratemporal epilepsies. Ictal ECD SPECT proved to be significantly more sensitive and specific than interictal ECD SPECT, and clinically useful in the definition of the epileptogenic zone.
authors.affiliation: Porto Allegre Epilepsy Surgery Program, Department of Internal Medicine, Hospital São Lucas, Pontificia Universidade Católica do Rio Grande do Sul, Brazil.
authors.forename: A J
authors.initials: AJ
authors.lastname: Oliveira
authors.forename: J C
authors.initials: JC
authors.lastname: da Costa
authors.forename: L N
authors.initials: LN
authors.lastname: Hilário
authors.forename: O E
authors.initials: OE
authors.lastname: Anselmi
authors.forename: A
authors.initials: A
authors.lastname: Palmini
mesh_terms: D000465:Algorithms; D002540:Cerebral Cortex / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003545:Cysteine / Q000031:analogs & derivatives*; D003663:Decision Trees; D004569:Electroencephalography; D004827:Epilepsy / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D015609:Organotechnetium Compounds; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon / Q000706:statistics & numerical data
chemical_list: D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime; C059659:technetium Tc 99m bicisate; D003545:Cysteine