Association between local gray matter volume differences and stereo-electroencephalography-defined epileptogenicity.

Area of Science:

• Neuroimaging
• Epilepsy Research
• Quantitative MRI

Background:

• Voxel-based gray matter volume (GMV) quantification has shown moderate success in identifying the epileptogenic zone (EZ).
• The definition of "ground truth" may influence the accuracy of GMV in EZ identification.
• Stereo-electroencephalography (SEEG) provides detailed electrophysiological data for localizing seizure onset.

Purpose of the Study:

• To investigate the association between GMV differences and SEEG-defined epileptogenicity.
• To explore GMV as a potential imaging biomarker for the EZ.
• To evaluate the utility of GMV in differentiating EZ from other brain regions in epilepsy patients.

Main Methods:

• Included 50 SEEG patients and 51 controls, performing voxel-based permutation inference on T1-weighted MRI scans.
• Classified SEEG contacts based on EZ definition (radiofrequency thermocoagulation) and active irritative zones (top 10% HFOs).
• Utilized mixed-effects logistic regressions and performance analysis to assess GMV associations with EZ and irritative zones.

Main Results:

• Increased GMV correlated with EZ contacts in the overall cohort (OR 1.21) and MRI-positive group (OR 1.45), but not MRI-negative.
• Reduced GMV was associated with EZ contacts in mesiotemporal regions (OR 0.53), while increased GMV was found in neocortical areas (OR 1.32).
• Within MRI-visible lesions, increased GMV positively associated with EZ contacts (OR 1.50). Increased GMV linked to neocortical irritative zone contacts in MRI-positive cases.

Conclusions:

• Local GMV differences are associated with EZ contacts in the whole cohort and MRI-positive patients.
• Associations varied by region, with positive links in the neocortex and negative in mesiotemporal structures.
• Increased GMV within MRI-visible lesions is a significant finding associated with EZ contacts.