Periictal SPECT Localization Verified by Simultaneous Intracranial EEG

Authors

  • Marianna V. Spanaki,

    1. Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, U.S.A.
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  • I. George Zubal,

    1. Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut, U.S.A.
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  • John MacMullan,

    1. Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut, U.S.A.
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  • Susan S. Spencer

    Corresponding author
    1. Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, U.S.A.
      Address correspondence and reprint requests to Dr. S. S. Spencer at Yale University School of Medicine, Department of Neurology, Box 208018, New Haven, CT 06520-8018, U.S.A.
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Address correspondence and reprint requests to Dr. S. S. Spencer at Yale University School of Medicine, Department of Neurology, Box 208018, New Haven, CT 06520-8018, U.S.A.

Abstract

Summary: Purpose: We investigated whether blood-flow changes measured by ictal or immediate postictal single photon emission computed tomography (SPECT) reflect with accuracy the actual location of ictal discharge as measured by simultaneous intracranial EEG. In addition, we evaluated the reliability of ictal SPECT obtained with implanted electrodes by comparing results with those of ictal SPECT performed during scalp EEG monitoring in selected patients.

Methods: Eleven patients with intractable partial epilepsy who had both ictal and interictal SPECT scans during invasive EEG monitoring were studied. We analyzed perfusion differences based on registration, normalization, and subtraction of perüctal and interictal SPECT images. SPECT results were interpreted in relation to location and evolution of ictal EEG change, as reflected by simultaneous intracranial EEG. In five patients, we also compared ictal SPECT results that were obtained during both scalp and intracranial EEG monitoring.

Results: In 10 of 11 patients, localized increases or decreases in blood flow or both were identified in regions of ongoing or prior seizure discharge, respectively, at the time of SPECT brain perfusion. In one patient, SPECT localization could not be verified by the available electrode array.

Conclusions: Localization of ictal discharge during or before SPECT injection accurately determines increase or decrease in perfusion, respectively, and both are of equal validity in reflecting the region of epileptic discharge. SPECT perfusion changes can be reliably obtained during intracranial monitoring.

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