SISCOS in focal cortical dysplasia: localization and comparative analysis with MRI.

Area of Science:

• Neuroimaging
• Epilepsy Surgery
• Nuclear Medicine

Background:

• Focal cortical dysplasia (FCD) is a leading cause of drug-resistant epilepsy (DRE).
• Accurate localization of the epileptogenic zone (EZ) is crucial for successful epilepsy surgery.
• Magnetic Resonance Imaging (MRI) is a primary tool, but its sensitivity can be limited in detecting FCD.

Purpose of the Study:

• To evaluate the efficacy of Subtraction ictal-interictal SPECT coregistered to SPECT (SISCOS) in localizing the EZ in FCD.
• To compare SISCOS performance with MRI in predicting post-surgical outcomes.
• To assess the added value of SISCOS in cases with discordant MRI findings.

Main Methods:

• 84 patients with DRE and FCD underwent SISCOS and MRI for EZ localization.
• Ictal and interictal SPECT scans used Tc-99m ECD, analyzed with SPM2 and Bioimage Suite.
• Localization concordance was compared to surgical resection, and outcomes assessed using the International League Against Epilepsy (ILAE) classification.

Main Results:

• SISCOS showed 73.8% concordance for EZ localization, while MRI had 82.1%.
• Overall, 61.9% of patients achieved good surgical outcomes, with 59% having FCD type 2.
• In MRI-discordant cases (15 patients), SISCOS localized the EZ in 86%, leading to good outcomes in 69.2%.

Conclusions:

• SISCOS is effective for EZ localization in FCD, with performance comparable to MRI.
• Integrating SISCOS with MRI improves lesion detection, particularly in MRI-discordant cases.
• A combined diagnostic approach optimizes pre-surgical assessment for DRE, guiding surgical decisions effectively.