High-Frequency Oscillation-Based Rotary Saturation: a functional imaging technique for epilepsy lateralization in MRI-negative patients

Motivation: Delineation of the seizure onset zone (SOZ) in surgical planning for drug-resistant epilepsy requires invasive procedures. The Stimulus-Induced Rotary Saturation (SIRS) sequence targets biomagnetic field associated with epileptic discharges. Goal(s): To evaluate the efficiency of SIRS in epilepsy lateralization using high-frequency oscillations (HFOs) as biomarkers and compare it with EEG and clinical seizure semiology. Approach: We investigated 11 epilepsy patients using SIRS at a 120 Hz spin-lock frequency, assessing the localizing value at hemispheric and lobar levels. Results: SIRS-identified activations were above threshold in 8 of 11 patients, offering potential for improved SOZ localization. Hemispheric concordance was found with EEG in 7 cases. Impact: Spin-lock based rotary saturation imaging lateralized brain areas in epilepsy patients with negative MRI findings in concordance with EEG and seizure semiology. Combined with state-of-the-art non-invasive methods such as EEG, it offers potential for improved seizure lateralization.