Superior localizing and prognostic value of statistical parametric SPECT analysis in temporal lobe epilepsy: A comparative study of ISAS and SISCOM.

PURPOSE: This study aimed to compare the localizing accuracy, interobserver reliability, and prognostic value of ictal SPECT analyzed by Statistical Parametric Mapping (ISAS) versus Subtraction Ictal SPECT Co-registered to MRI (SISCOM) in patients with drug-resistant temporal lobe epilepsy (TLE).

METHODS

Sixty consecutive TLE patients who underwent resective epilepsy surgery were analyzed. All ictal SPECT studies were processed by ISAS and SISCOM. Two blinded reviewers independently identified the most prominent hyperperfusion regions across 40 predefined brain subregions. Localization concordance with the actual resection site was scored at both lobar and sublobar levels. Interobserver agreement and the correlation between imaging localization and postsurgical seizure outcomes were analyzed.

RESULTS

ISAS achieved significantly higher interobserver agreement than SISCOM for the localization (κ = 0.34-0.88 vs. 0.14-0.69). ISAS concordance with surgical resection was 88.7% at the lobar level and 79.7% at the sublobar level, compared to 71.7% and 60.9% for SISCOM, respectively. Logistic regression revealed that only ISAS localization at both scales significantly predicted seizure-free outcome, whereas SISCOM did not.

CONCLUSIONS

ISAS outperforms SISCOM in both localizing accuracy and observer reliability, and its concordance with surgical resection robustly predicts postoperative seizure freedom. These findings support the adoption of ISAS as the first-line SPECT postprocessing technique for presurgical evaluation of TLE.