Overcome SQUID & alkali OPM limitations for Epilepsy: 4He OPMs – MEO

The main objective of this highly interdisciplinary and collaborative project is to demonstrate that innovative optically pumped magnetometers (OPM) using helium-4 (4HeOPM) can overcome the limitations of SQUID and alkali OPM sensors to monitor brain activity in epileptic patients including children and to perform long-term recording of epileptic seizures.
Magnetoencephalography (MEG) allows to explore brain activity in real time, by offering millisecond-order temporal resolution to track the magnetic activity at the surface of the scalp, with higher spatial resolution compared to EEG. MEG can be used to non-invasively detect and localise abnormal activity in epileptic patients for surgical purposes, since the irritative zone producing interictal abnormalities is related to the epileptogenic zone (EZ) to be removed to achieve seizure freedom. MEG can help to identify the EZ and thus indicate direct surgical intervention, but also to identify areas to be sampled with deep electrodes when invasive recording is required, ultimately contributing to improve surgical outcome. However, its routine clinical use is limited by excessive cost, the immobility imposed on patients does not allow long term recording of seizures and its rigid helmet is not adapted to the morphology of children's heads.
Innovative optically pumped magnetometers (OPMs) using helium-4 (4HeOPM) have been developed by Mag4Health, which operate at room temperature. These sensors can be placed near the scalp and have a wider dynamic range and bandwidth more suitable for detecting epileptic activities. Our aim is to demonstrate their capability to overcome the limitations of commercially available MEG systems (sMEGs) as well as prototype alkaline OPM, thus opening new horizons for the non-invasive pre-surgical evaluation of epilepsy including recording of seizure onset.
To achieve this objective, a multidisciplinary consortium with very complementary skills and expertise has been set up, including 3 research institutes, 1 University Hospital and 1 SME, which have already established fruitful collaborations in the past. Thanks to the excellent respective expertise of all partners and the continuous interaction, we will tackle several challenges: 1) finalize a 72-channels (24 sensors) 4HeOPM MEG system suitable for patient’s morphology and long-term monitoring; 2) implement software and hardware solutions for movements artefacts correction and signal denoising; 3) validate the sensitivity of 4HeOPM compared to sMEG to brain activity (epileptic spikes and High Frequency Oscillations), by performing simultaneous intracerebral SEEG/sMEG and SEEG/4HeOPM recordings on the same epileptic patients; 4) evaluate the capability of 4HeOPM to record interictal events for presurgical evaluation in epileptic children in comparison with sMEG; 5) take advantage of the wearable He4OPM headset to perform long-term simultaneous He4OPM/HREEG recording to acquire spontaneous seizures in patients. During all the phases of this project, intensive communication and exchange between the researchers, engineers and physicians of the MEO network will feed the technical developments, experimental tests, acquisition, and analysis of high-quality data.
This highly interdisciplinary project combines the development and validation of innovative sensors with their evaluation and application in clinical settings. It will ultimately lead to the final specification of the first industrial version of the whole head 4He OPM MEG system developed by MAG4Health, thus opening new horizons for large-scale clinical application of MEG in epilepsy and beyond.