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Updated: May 24, 2026
Electromagnetic Source Imaging in Presurgical Evaluation of Children with Drug-Resistant Epilepsy
Published on: September 20, 2024
SISCOM technique with a variable Z score improves detectability of focal cortical dysplasia: a comparative study with
Yukio Kimura1, Noriko Sato, Kimiteru Ito
1Department of Radiology, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi-cyo, Kodaira, Tokyo, 187-8511, Japan.
Objective:
Focal cortical dysplasia (FCD) is one of the causes of epilepsy, but its diagnosis by MRI remains difficult. The purpose of this study was to evaluate the use of subtraction ictal SPECT coregistered to MRI (SISCOM) and MRI to detect the epileptogenic focus in patients with FCD.
Methods:
MRI and SISCOM findings of 20 patients with pathologically proven FCD were retrospectively reviewed. MRI was visually assessed for detecting FCD. SISCOM was evaluated by a new method selecting a higher standard deviation (Z score) area as the epileptogenic focus. We scored the detectability in both SISCOM and MRI while referring to the pathology.
Results:
Sixteen patients agreed with pathology on SISCOM and 14 patients on MRI. Although MRI could not point out foci in two cases of FCD type I, SISCOM could do so in both of them. A combined diagnosis of SISCOM and MRI agreed with the pathology in 18 patients.
Conclusions:
Narrowing the target by elevating the Z score on SISCOM seems to be an appropriate method to detect the foci without the need for expertise of radiologists. We recommend this combined method of SISCOM and MRI for presurgical evaluation in patients with FCD.
Insights
Subtraction ictal SPECT coregistered to MRI (SISCOM) combined with MRI effectively detects the epileptogenic focus in focal cortical dysplasia (FCD) patients. This combined approach improves presurgical evaluation for epilepsy surgery.
Area of Science:
- Neurology
- Radiology
- Epileptology
Background:
- Focal cortical dysplasia (FCD) is a significant cause of epilepsy.
- Diagnosing the epileptogenic focus in FCD using MRI alone can be challenging.
Purpose of the Study:
- To evaluate the efficacy of subtraction ictal SPECT coregistered to MRI (SISCOM) and MRI in detecting the epileptogenic focus in patients with FCD.
- To compare the diagnostic performance of SISCOM and MRI against pathological findings.
Main Methods:
- Retrospective review of MRI and SISCOM findings in 20 patients with pathologically confirmed FCD.
- Visual assessment of MRI for FCD detection.
- Evaluation of SISCOM using a novel method focusing on higher standard deviation (Z score) areas as potential epileptogenic foci.
- Scoring the detectability of foci by both modalities against histopathological results.
Main Results:
- SISCOM correctly identified the epileptogenic focus in 16 out of 20 patients, while MRI identified it in 14 patients.
- SISCOM successfully detected foci in two cases of FCD type I where MRI was unable to.
- The combined use of SISCOM and MRI showed agreement with pathology in 18 patients.
Conclusions:
- Elevating the Z score threshold on SISCOM offers a reliable method for focus detection, potentially reducing the need for specialized radiologist interpretation.
- The combined approach of SISCOM and MRI is recommended for presurgical evaluation in patients with FCD.
- This method enhances the localization of epileptogenic zones for improved surgical outcomes.
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