title: Usefulness of ictal and interictal 99mTc ethyl cysteinate dimer single photon emission computed tomography in patients with refractory partial epilepsy.
abstract: OBJECTIVE
  Ictal perfusion single photon emission computed tomography (SPECT), using HMPAO, has been shown to localize epileptic foci in approximately 90% of studies. Unfortunately, HMPAO decomposes rapidly, precluding the performance of ictal studies. Ethyl cysteinate dimer (ECD) is a SPECT perfusion agent recently approved by the Food and Drug Administration. After preparation, this compound is stable for approximately 6 h. facilitating the performance of ictal studies.
  
  
  METHODS
  In a prospective, open-label, uncontrolled, non randomized study, we evaluated the potential benefits of the use of 99mTc-ECD SPECT for lateralization of the epileptic focus. Ten consecutive adult epilepsy surgery candidates were studied with ictal and interictal 99mTc-ECD SPECT.
  
  
  RESULTS
  The mean delay between seizure onset and ictal SPECT injection was 23.2 s. The mean seizure duration was 84.1 s. Ictal studies agreement between the epilepsy focus and area of hyperperfusion was evident in 8 of 10 cases. In one case, SPECT was lateralized in a patient with bilateral temporal lobe epilepsy (TLE); however, hyperperfusion was observed on the same side of that particular seizure. In another case, there was location disagreement. Interictal SPECT showed focal hypoperfusion in three cases.
  
  
  CONCLUSIONS
  99mTc-ECD proved to be an optimal tracer for ictal studies. Although this is a small series, the results of ictal and interictal findings using 99mTc-ECD are similar to those reported with 99mTc-HMPAO. Because 99mTc-ECD has a longer decomposition time, true ictal studies are easier to obtain. This new tracer will probably allow the use of ictal SPECT to become widely accepted in most epilepsy centers.
authors.affiliation: Section of Epilepsy and Sleep Disorders, The Cleveland Clinic Foundation, Ohio, U.S.A.
authors.forename: M E
authors.initials: ME
authors.lastname: Lancman
authors.forename: H H
authors.initials: HH
authors.lastname: Morris
authors.forename: S
authors.initials: S
authors.lastname: Raja
authors.forename: M J
authors.initials: MJ
authors.lastname: Sullivan
authors.forename: G
authors.initials: G
authors.lastname: Saha
authors.forename: R
authors.initials: R
authors.lastname: Go
mesh_terms: D000328:Adult; D017668:Age of Onset; D002540:Cerebral Cortex / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000175:diagnosis / Q000000981:diagnostic imaging*; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000000981:diagnostic imaging; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D011446:Prospective Studies; D012039:Regional Blood Flow; D017556:Technetium Compounds; D013702:Temporal Lobe / Q000098:blood supply / Q000000981:diagnostic imaging / Q000503:physiopathology; D015899:Tomography, Emission-Computed, Single-Photon; D014743:Videotape Recording
chemical_list: D015609:Organotechnetium Compounds; D017556:Technetium Compounds