title: The promise of subtraction ictal SPECT co-registered to MRI for improved seizure localization in pediatric epilepsies: Affecting factors and relationship to the surgical outcome.
abstract: Ictal SPECT is promising for accurate non-invasive localization of the epileptogenic brain tissue in focal epilepsies. However, high quality ictal scans require meticulous attention to the seizure onset. In a relatively large cohort of pediatric patients, this study investigated the impact of the timing of radiotracer injection, MRI findings and seizure characteristics on ictal SPECT localizations, and the relationship between concordance of ictal SPECT, scalp EEG and resected area with seizure freedom following epilepsy surgery.
  
  
  
  Scalp EEG and ictal SPECT studies from 95 patients (48 males and 47 females, median age=11years, (25th, 75th) quartiles=(6.0, 14.75) years) with pharmacoresistant focal epilepsy and no prior epilepsy surgery were reviewed. The ictal SPECT result was examined as a function of the radiotracer injection delay, seizure duration, epilepsy etiology, cerebral lobe of seizure onset identified by EEG and MRI findings. Thirty two patients who later underwent epilepsy surgery had postoperative seizure freedom data at <1, 6 and 12 months.
  
  
  
  Sixty patients (63.2%) had positive SPECT localizations - 51 with a hyperperfused region that was concordant with the cerebral lobe of seizure origin identified by EEG and 9 with discordant localizations. Of these, 35 patients (58.3%) had temporal and 25 (41.7%) had extratemporal seizures. The ictal SPECT result was significantly correlated with the injection delay (p<0.01) and cerebral lobe of seizure onset (specifically frontal versus temporal; p=0.02) but not MRI findings (p=0.33), epilepsy etiology (p≥0.27) or seizure duration (p=0.20). Concordance of SPECT, scalp EEG and resected area was significantly correlated with seizure freedom at 6 months after surgery (p=0.04).
  
  
  
  Ictal SPECT holds promise as a powerful source imaging tool for presurgical planning in pediatric epilepsies. To optimize the SPECT result the radiotracer injection delay should be minimized to≤25s, although the origin of seizure onset (specifically temporal versus frontal) also significantly impacts the localization.
authors.affiliation: Harvard Medical School, Boston MA 02115, USA; Department of Radiology, Boston Children's Hospital, Boston MA 02115, USA; Department of Neurology, Boston Children's Hospital, Boston MA 02115, USA; Division of Adolescent Medicine, Boston Children's Hospital, Boston MA 02115, USA. Electronic address: caterina.stamoulis@childrens.harvard.edu.
authors.forename: Catherine
authors.initials: C
authors.lastname: Stamoulis
authors.affiliation: Scottsdale Medical Imaging, Scottsdale, AZ 85252, USA.
authors.forename: Nishant
authors.initials: N
authors.lastname: Verma
authors.affiliation: Harvard Medical School, Boston MA 02115, USA; Department of Neurology, Boston Children's Hospital, Boston MA 02115, USA.
authors.forename: Himanshu
authors.initials: H
authors.lastname: Kaulas
authors.affiliation: Department of Neurology, Medical University of South Carolina, Charleston, SC 29425, USA.
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Halford
authors.affiliation: Harvard Medical School, Boston MA 02115, USA; Department of Neurology, Boston Children's Hospital, Boston MA 02115, USA.
authors.forename: Frank H
authors.initials: FH
authors.lastname: Duffy
authors.affiliation: Harvard Medical School, Boston MA 02115, USA; Department of Neurology, Boston Children's Hospital, Boston MA 02115, USA.
authors.forename: Phillip L
authors.initials: PL
authors.lastname: Pearl
authors.affiliation: Harvard Medical School, Boston MA 02115, USA; Department of Radiology, Brigham and Women's Hospital, Boston MA 02115, USA.
authors.forename: S Ted
authors.initials: ST
authors.lastname: Treves
mesh_terms: D000293:Adolescent; D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D001931:Brain Mapping; D002648:Child; D002675:Child, Preschool; D000069279:Drug Resistant Epilepsy / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D064847:Multimodal Imaging; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012640:Seizures / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals
keywords: Ictal SPECT; Pediatric epilepsies; Postsurgical outcome; Radiotracer injection