Assessment of localization accuracy and postsurgical prediction of simultaneous 18F-FDG PET/MRI in refractory epilepsy patients

Abstract

Objectives: To evaluate the accuracies of simultaneous ¹⁸F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging ([¹⁸F]-FDG PET/MRI) in preoperative localization and the postsurgical prediction.

Methods: This retrospective study was performed on ninety-eight patients diagnosed with refractory epilepsy whose presurgical evaluation included [¹⁸F]-FDG PET/MRI, with 1-year post-surgery follow-up between August 2016 and December 2018. PET/MRI images were interpreted by two radiologists and a nuclear medicine physician to localize the EOZ using standard visual analysis and asymmetry index based on standard uptake value (SUV). The localization accuracy and predictive performance of simultaneous ¹⁸F-FDG PET/MRI based on the surgial pathology and postsurgical outcome were evaluated.

Results: A total of 41.8% (41/98) patients were found to have a definitely structural abnormality on the MR portion of PET/MRI; 93.9% (92/98) were shown hypometabolism on the PET portion of the hybrid PET/MRI. PET/MRI identified 18 cases with subtle structural abnormalities on MRI re-read. Six percent (6/98) of patients PET/MRI were negative. A total of 65.3% (64/98) patients showed seizure-free at 1-year follow-up after epilepsy surgery. The sensitivity, specificity, and accuracy of [¹⁸F]-FDG PET/MRI was 95.3%, 8.8%, and 65.3% for seizure onset localization based on surgical pathology and postsurgical outcome, respectively. Multivariate regression analysis indicated that concordant of EOZ localization between PET/MRI and surgical resection range, which was a good positive predictor of seizure freedom (Engel I) (OR = 14.741, 95% CI 3.934-55.033, p < 0.001).

Conclusions: [¹⁸F]-FDG PET/MRI used as two combined modalities providing additional sensitivity when detecting possible epileptic foci and will probably improve the surgical outcome.

Key points: • Sensitivity, specificity, and accuracy of [¹⁸F]-FDG PET/MRI were 95.3%, 8.8%, and 65.3% for seizure onset localization based on surgical pathology and postsurgical outcome, respectively. • Concordance of EOZ localization between PET/MRI and surgical resection range was a good positive predictor of seizure freedom; presurgical [¹⁸F]-FDG PET/MRI will probably improve the surgical outcome.

Keywords: Epilepsy; Magnetic resonance imaging; Positron emission tomography; Prognosis; Surgery.