Development of a lifespan compliant magnetoencephalography system

Epilepsy affects around 1 in every 200 children. It is one of the most serious long-term health conditions in childhood and is highly debilitating, affecting physical and mental health. Unfortunately, whilst epilepsy can be treated using drugs, these are ineffective in ~30% of cases, and many patients experience difficulties in learning and behaviour. In carefully selected children, surgery can be curative, but this requires careful planning, ensuring abnormal brain tissue is removed without damaging healthy tissue surrounding it. Planning requires advanced brain imaging, but existing technologies often prove insufficient. In children, the most common cause of drug resistant epilepsy occurs is abnormal cortical development, a condition known as focal cortical dysplasia (FCD). FCD can sometimes be seen on MRI scans but it is subtle, and often missed, so other techniques are critically required to supplement MRI.

It is possible to measure electrical brain activity, including that resulting in epileptic seizures, directly; either invasively (by putting electrodes into the brain) or non-invasively via electrodes on the scalp with electroencephalography (EEG) or by measuring magnetic fields above the scalp using magnetoencephalography (MEG). Invasive measures precisely pinpoint the source of the seizures, but they require significant surgery and only small regions of brain can be assessed (so we need to have a clear plan for where to put the electrodes). EEG is clinically widely available, covers the whole brain, but it provides a blurred picture of where seizures are generated. MEG offers a more detailed picture of activity across the whole brain and has been shown to significantly increase the chances of surgical success. However, current MEG scanners are extremely expensive and impractical (because patients have to keep still for long periods). They are also not well-suited for use in children.

Recently, we have built a new type of MEG scanner. Unlike traditional devices which are large and heavy, our scanner can be worn on the head like a helmet. Because the scanner moves with the head, scans can still be generated when patients make large movements. In addition, our wearable scanner can measure brain activity with much greater detail and is cheaper and easier to maintain. Thus far, this scanner has only been developed for adults, we now plan to design and build a system for children.

There are a number of major technical barriers that we have to address: We will start by tackling the fundamental problems associated with scanning young children, including questions like how to get the best possible spatial precision and how to ensure magnetic field sensors (the fundamental building block of a MEG system) can work when tightly packed together on a child's head. We will ensure that data are unaffected by subject movement, and we will tailor our array to specifically focus on brain regions known to be vulnerable to FCD. We will address the problem of how to actually build a wearable MEG helmet for infants; making it robust and practical, but also something with which children (and their parents) will happily engage. We will develop the mathematical methods required to form accurate images of brain activity from the MEG data. Finally, we will deploy our system in both healthy children (to validate it) and in infants with epilepsy.

We expect that our system will offer neurologists a window on abnormal brain function with unparalleled accuracy. We will compare our results to high performance MRI (to show concordance with FCD) and with invasive EEG, showing that our system offers similar information to invasive measurements, but without the need for surgery. Ultimately, we aim to show that our device offers new information on abnormal brain function which will be game-changing for youngsters suffering with this highly debilitating disorder.