Comparative Analysis of SPECT and PET in the Localization of the Epileptogenic Focus During Surgical Planning

Introduction: Neuroimaging studies are fundamental for identifying the epileptogenic focus, which is essential for lesion-concordant resection and successful postoperative outcomes. The concordance of structural, perfusion, and metabolic changes observed through neuroimaging forms the basis of pre-surgical epilepsy evaluation. This study ssess the effectiveness of Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) in locating the epileptogenic focus in patients with mesial temporal sclerosis (MTS).

Methods: A retrospective analysis was conducted on 60 patients who underwent SPECT and 49 who underwent PET, comparing the results with Video-EEG and Magnetic Resonance Imaging (MRI). Surgical outcomes were assessed using the Engel classification immediately post-surgery and at the latest medical evaluation. Kendall's tau correlation and Krippendorf's alpha concordance tests were used to assess agreement between imaging techniques. Additionally, logistic regression was applied to identify key variables for localizing the epileptogenic focus and achieving optimal postsurgical outcomes (Engel I).

Results: PET identified the epileptogenic lesion in 87.8% of cases, compared to 85% identified by SPECT. PET showed a stronger correlation with Video-EEG and MRI (correlation coefficient =0.713 and 0.713 respectively) and greater concordance (alpha = .8171). The longer the duration of the epileptic seizure recorded by neuroimaging techniques, the more precise the localization of the epileptogenic focus (p=0.009). Furthermore, the concordance between the three neuroimaging studies increased the probability of optimal surgical success (Engel I) by 8 times (p=0.041).

Conclusion : Interictal PET is slightly superior to Interictal SPECT in localizing the epileptogenic focus for surgical planning in patients with MTS, showing better correlation when combined with Video-EEG and MRI.