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Updated: Dec 27, 2025
Author Spotlight: Advancing Pediatric Epilepsy Surgery in Children Through Novel Biomarkers and Enhanced Localization
Published on: September 20, 2024
Subtraction Ictal SPECT coregistered to MRI (SISCOM) as a guide in localizing childhood epilepsy
Thomas Foiadelli1, Lieven Lagae2, Karolien Goffin3
1Pediatric Clinic Fondazione IRCCS Policlinico San Matteo University of Pavia Pavia Italy.
Insights
Subtraction ictal SPECT coregistered to MRI (SISCOM) is a feasible and effective tool for localizing the epileptogenic zone in children undergoing epilepsy surgery evaluation. This method provides valuable presurgical information, particularly for patients with non-informative MRI or unclear video-EEG findings.
Area of Science:
- Neurology
- Nuclear Medicine
- Radiology
Background:
- Epilepsy surgery requires precise localization of the epileptogenic zone (PEZ).
- Subtraction ictal SPECT coregistered to MRI (SISCOM) is a neuroimaging technique used to aid PEZ localization.
Purpose of the Study:
- To evaluate the feasibility and efficacy of SISCOM for epilepsy localization in pediatric patients considered for resective surgery.
- To compare SISCOM's localization accuracy with other neuroimaging modalities and video-EEG findings.
Main Methods:
- Retrospective review of 44 pediatric patients (≤16 years) with drug-resistant epilepsy undergoing epilepsy surgery screening.
- Analysis of 51 SISCOM studies, assessing feasibility variables and comparing SISCOM localization with presumed epileptogenic zone (PEZ) determined by video-EEG.
Main Results:
- SISCOM was feasible in pediatric epilepsy surgery candidates, with timely radiotracer injection and imaging.
- SISCOM accurately localized the PEZ in 51.0% of cases and improved localization compared to ictal SPECT, FDG-PET, and MRI (P < .01).
- SISCOM was particularly useful in MRI-negative (27.8%) and poorly localizing video-EEG cases (25%), with a localizing SISCOM associated with better seizure freedom rates post-surgery (66.7%).
Conclusions:
- SISCOM is a reliable, feasible, and useful tool for localizing the epileptogenic zone in pediatric epilepsy surgery candidates.
- SISCOM provides critical presurgical information, especially when MRI is non-informative or video-EEG is poorly localizing.
- Successful SISCOM localization correlates with improved seizure outcomes following resective surgery.
Objective:
To assess feasibility and efficacy of subtraction ictal SPECT coregistered to MRI (SISCOM) for epilepsy localization in children who are candidates for resective surgery.
Methods:
We retrospectively reviewed all patients ≤16 years with drug-resistant epilepsy screened for epilepsy surgery in the University Hospital of Leuven from January 2009 to January 2018. Fifty-eight hospitalizations for ictal SPECT and 51 SISCOM analyses in 44 patients were included. Mean age was 9.1 years. Hospitalizations for SISCOM were analyzed in terms of multiple variables affecting feasibility and efficacy. The localization of SISCOM was compared with the localization of the presumed epileptogenic zone (PEZ) as determined by video-EEG.
Results:
SISCOM was feasible in terms of chronic medication management, rescue antiepileptic therapy during hospitalization, and operative timings. Radiotracer injection occurred within 30 seconds from seizure onset in 91.4% of the patients. ictal SPECT imaging was performed within two hours from injection in 100% of the patients (mean: 40 minutes). SISCOM was able to localize the PEZ in 51.0% (26/51) and to additionally lateralize the PEZ in 17.6% (9/51), achieving better localizations than ictal SPECT, FDG-PET, and MRI (P < .01). SISCOM was useful to localize the PEZ in 25% of patients with poorly localizing video-EEG and in 27.8% of MRI-negative cases. The occurrence of habitual seizures during injection for ictal SPECT and the temporal localization of the PEZ both correlated with a better SISCOM localization (P < .05). 36.4% (16/44) patients were finally selected for resective surgery, with a 87.5% seizure-free rate at 12 months. A localizing SISCOM was associated with seizure freedom in 66.7% and with a Engel I-II in 75.0% of our patients.
Significance:
SISCOM is a reliable tool to localize the epileptogenic zone in clinical practice and is both feasible and useful in children, adding precious presurgical information especially in patients with noninformative MRI or a poorly localizing video-EEG.
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