Individual localization value of resting-state fMRI in epilepsy presurgical evaluation: A combined study with stereo-EEG

Abstract

Objective: To examine the individual-patient-level localization value of resting-state functional MRI (rsfMRI) metrics for the seizure onset zone (SOZ) defined by stereo-electroencephalography (SEEG) in patients with medically intractable focal epilepsies.

Methods: We retrospectively included 19 patients who underwent SEEG implantation for epilepsy presurgical evaluation. Voxel-wise whole-brain analysis was performed on 3.0 T rsfMRI to generate clusters for amplitude of low-frequency fluctuations (ALFF), regional homogeneity (ReHo) and degree centrality (DC), which were co-registered with the SEEG-defined SOZ to evaluate their spatial overlap. Subgroup and correlation analyses were conducted for various clinical characteristics.

Results: ALFF demonstrated concordant clusters with SEEG-defined SOZ in 73.7% of patients, with 93.3% sensitivity and 77.8% PPV. The concordance rate showed no significant difference when subgrouped by lesional/non-lesional MRI, SOZ location, interictal epileptiform discharges on scalp EEG, pathology or seizure outcomes. No significant correlation was seen between ALFF concordance rate and epilepsy duration, seizure-onset age, seizure frequency or number of antiseizure medications. ReHo and DC did not achieve favorable concordance results (10.5% and 15.8%, respectively). All concordant clusters showed regional activation, representing increased neural activities.

Conclusion: ALFF had high concordance rate with SEEG-defined SOZ at individual-patient level.

Significance: ALFF activation on rsfMRI can add localizing information for the noninvasive presurgical workup of intractable focal epilepsies.

Keywords: Amplitude of low-frequency fluctuations (ALFF); Epilepsy; Presurgical evaluation; Stereo-electroencephalography (SEEG); resting-state functional magnetic resonance imaging (rsfMRI).