Developing and Assessing Wearable MEG for Children

Project Summary/Abstract Childhood epilepsy accounts for 470,000 cases in the US and 10.5 million cases worldwide. Approximately 30% of children with epilepsy have seizures that are pharmacologically intractable, making these patients candidates for surgical intervention. In adults with intractable epilepsy, pre-surgical workup involves source localization of interictal epileptiform discharges (IEDs) from magnetoencephalography (MEG). Source locali- zation of IEDs on MEG are increasingly utilized as a routine component of the presurgical evaluation to local- ize epileptic tissue. However, although many surgical epilepsy programs have an MEG center, this technology is not routinely available for use in children because current SQUID-based MEG systems use fixed adult- sized sensor helmets not appropriate for pediatric head sizes that vary with age. A new MEG technology based on optically pumped magnetometers (OPM) is emerging that can overcome this challenge because it can accommodate variable head sizes. However, to translate this sensor technology to pediatric populations, a system that is age-appropriate and robust to movement artifacts must be developed. In Aim 1, We will de- velop and optimize an OPM-MEG recording system for use in children. We have already developed a weara- ble OPM-MEG helmet for use in adults. We will extend this method by designing age-matched helmets that can be comfortably worn by children with optimized fit. Moreover, in children, head movements create addi- tional artifacts due to the movement of sensors within the background field gradients. We will develop addi- tional nulling coils to fully cancel the background gradient fields and software to adaptively cancel drifting fields thereby suppressing these artifacts. In Aim 2, we will evaluate the system first on healthy children using somatosensory evoked responses. We will compare the estimated dipole locations during natural head movements in OPM-MEG and SQUID-MEG. Then, we will apply it on pediatric patients for the detection of IEDs and compare the confirmed IED locations from intracranial EEG to the estimated source locations from OPM-MEG and SQUID-MEG.