1st supervisor: David Carmichael, King’s College London
2nd supervisor: Ozlem Ipek, King’s College London
Industry Supervisor: Tracy Warbrick, Brain Products
Clinical Champion: Alexander Hammers, King’s College London
Aim of the PhD Project:
To optimise simultaneous EEG and fMRI recordings at 7T, requiring us to:
- Characterise image quality minimising any impact of the EEG equipment
- Characterise and improve EEG data quality
- Assess safety risks and define safe modes of operation
- Demonstrate feasibility for clinical studies in children and/or adults with focal epilepsy
Project Description / Background:
Epilepsy is the most common neurological condition in children. For adults and children with focal epilepsy, surgical removal of the brain region responsible for seizure generation is the only possible complete cure. This can potentially remove dependence on medication, and dramatically improve quality of life. Surgical success relies on accurate localisation of the generators of epileptic activity via imaging techniques such as MRI and electroencephalography (EEG). These two key modalities can be combined; epileptic activity measured in EEG is used as a model of expected changes in functional MRI timeseries. This provides a high spatial resolution map showing the areas with signal changes associated with the epileptic activity, as such simultaneous EEG-fMRI has been shown to be a useful localisation method(1).
However, EEG-fMRI is limited by fMRI sensitivity that typically measures signal changes of 1-2%, while the fact that the epileptic activity occurs spontaneously further limits sensitivity (i.e. due to the unpredictable number and distribution of events). Ultra high-field 7T MRI offers a solution because fMRI signal changes are substantially increased in magnitude to 5-10% and this could dramatically improve the technique’s sensitivity and spatial specificity.
However, simultaneous EEG-fMRI at 7T MRI scanner is a significant challenge that needs to be overcome to enable patient benefit. This project is needed to design and test a new optimal EEG configuration for use at 7T. This will include investigating the risk of tissue heating and EEG system design solutions to mitigate this. Further, the impact of each modality on the other in terms of data quality will be characterised and the EEG system hardware configuration redesigned to optimise signal quality. This may also encompass potential algorithmic development to improve image quality, including AI methods to improve upon current denoising approaches. Having optimised 7T EEG-fMRI an initial pilot investigation of its utility in epilepsy is envisaged.
This project benefits from being sponsored by, and involving close collaboration with an industry partner (Brain Products, GmBH) the market leader in research EEG-fMRI equipment. In addition to providing hardware and expertise via PhD supervision they will also provide a unique opportunity for a placement embedded within their technical team. This will be designed to maximise the students experience and development with opportunities to work with the brain computer interface (BCI) Brain Products team in Germany.
Students from a wide range of engineering or physical science or certain neuroscience backgrounds would be suitable for this project with the potential to focus on the aspects most relevant to these subjects.
Alpha power variation when an eyes-open/eyes-closed task captured during simultaneous EEG-fMRI (top image and right image acquired by EEG and brain images below acquired by 7T fMRI).
References:
- Centeno M, Tierney TM, Perani S, Shamshiri EA, St Pier K, Wilkinson C, Konn D, Vulliemoz S, Grouiller F, Lemieux L, Pressler RM, Clark CA, Cross JH, Carmichael DW. Combined electroencephalography-functional magnetic resonance imaging and electrical source imaging improves localization of pediatric focal epilepsy. Ann Neurol. 2017 Aug;82(2):278-287