Abstract
Objective
This study aimed to investigate the quantitative relationship between interictal 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) and interictal high frequency oscillations (HFOs) from stereoelectroencephalography (SEEG) recordings in refractory epilepsy patients.
Methods
We retrospectively included 32 patients. FDG-PET data were quantified through statistical parametric mapping (SPM) t-test modeling with normal controls. Interictal SEEG segments with four 10-min segments were randomly selected. HFO detection and classification procedures were automatically performed. Channel-based HFOs separating ripple (80-250Hz) and fast ripple (FR, 250-500Hz) counts were correlated with the surrounding metabolism T score at individual and group level respectively. The association was further validated across anatomical seizure origins and sleep versus wake states. We built a joint feature FR×T reflecting the FR and hypometabolism concordance to predict surgical outcome in 28 patients who underwent surgery.
Results
We found a negative correlation between interictal FDG-PET and HFOs through the linear mixed effect model (R2 = 0.346 and 0.457 for ripple and FR, respectively, p < 0.001); these correlations were generalizable to different epileptogenic zone lobar localizations and vigilance states. The FR×T inside the resection volume could be used as a predictor for surgical outcomes with an area under the curve of 0.81.
Significance
The degree of hypometabolism is associated with HFO generation rate, especially for the FRs. This relationship would be meaningful for selection of SEEG candidates and optimizing SEEG scheme planning. The concordance between FR and hypometabolism combing surgical information could provide prognostic information regarding surgical outcome.
DIC