A comparative study on the detection and localization of interictal epileptiform discharges in magnetoencephalography...

Superconducting quantum interference device (SQUID)-based magnetoencephalography (MEG) holds substantial clinical value in epilepsy examination but is limited by the high costs. The optically pumped magnetometer (OPM)-based MEG appears promising in overcoming these limitations. This study aims to explore the consistency of interictal epileptiform discharge (IED) detection and source localization between OPM-MEG and SQUID-MEG in a large cohort of patients with epilepsy.

Patients with epilepsy underwent SQUID-MEG and 128-channel whole-scalp OPM-MEG examinations. IED detection, amplitude, signal-to-noise ratio (SNR), sensor-scalp distance, and source localization results were compared between OPM-MEG and SQUID-MEG through statistical analysis.

The cohort comprised 46 patients with epilepsy (mean age, 23.7 ± 8.7 [SD] years; 29 male). McNemar χ² test indicated no significant difference for IED detection between two systems. OPM-MEG achieved a detection accuracy of 91.3 % compared with SQUID-MEG; a Gwet's first-order agreement coefficient (AC₁) of 0.892 suggested good consistency. Among 39 patients with IEDs detected by both systems, OPM-MEG demonstrated closer sensor-scalp distance (p < 0.001), higher IED amplitude (p < 0.001) and SNR (p = 0.003) compared with SQUID-MEG. At the sublobar level, OPM-MEG and SQUID-MEG exhibited nearly consistent source localization results. Among 24 patients with single dipole clusters, the average centroid distance between dipole clusters of OPM-MEG and SQUID-MEG was 12.16 ± 5.90 mm.

This real-world study demonstrated that OPM-MEG had comparable applicability in IED detection and source localization, compared with SQUID-MEG. Additionally, OPM-MEG performed better in terms of IED amplitude and SNR. Lower costs and user-friendly features highlight the clinical potential of OPM-MEG in epilepsy assessments.