Yield of MRI, high-density electric source imaging (HD-ESI), SPECT and PET in epilepsy surgery candidates

•High-density electric source imaging (HD-ESI) in combination with MRI are the best predictors of a favorable postoperative outcome, in terms of complete seizure control.•PET and SPECT are also associated with good postoperative outcome, but their predictive value is not as high as HD-ESI.•Our study brings in an important contribution to the validation of HD-ESI as a clinically useful first-line tool.

ObjectivePreoperative workup aims at localizing the epileptogenic focus to achieve postoperative seizure-freedom. We studied the predictive value of non-invasive techniques, i.e. structural magnetic resonance imaging [MRI], high-density electric source imaging [HD-ESI] and metabolic imaging (positron emission tomography [PET]; single-photon emission computed tomography [SPECT]), in surgically treated patients.MethodsA prospective study of 190 epileptic operated patients, with >12 months follow-up and analyzed with state-of-the-art algorithms. 58 patients underwent all techniques. We computed sensitivity, specificity, predictive value and diagnostic odds ratio (OR) in relation to postoperative outcome.ResultsOf 190 patients, 148 (77.9%) were seizure-free at follow-up. Resection of the epileptogenic focus was associated with favorable postsurgical outcome (p < 0.05). Among 58 patients who underwent all tests, only MRI and HD-ESI were favorable outcome predictors (MRI: OR 10.9, p = 0.004; HD-ESI: OR 13.1, p = 0.004). Patients with concordant structural MRI and HD-ESI results had 92.3% (24/26) probability of favorable outcome. When both results were negative, probability was 0% (0/5); and when they disagreed, it was 63.0% (17/27).ConclusionsCombination of MRI and HD-ESI offered the highest predictive value for postoperative seizure-freedom.SignificanceThis finding highlights the added value of HD-ESI in the presurgical workup, in particular in combination with an informative MRI.