Prof J Hajnal
Applications accepted all year round
About the Project
Neurostimulation is a promising treatment for intractable motor disorders and epilepsy that has huge potential for children, in whom early intervention to modulate neural circuits can dramatically improve function and prevent secondary deterioration that makes later treatment less effective (DOI:10.1212/WNL.0000000000001312). Precise placement of deep brain stimulation electrodes is critical but challenging because the target brain structures can barely be delineated on conventional MRI at clinical field strength, and are even smaller in children than in adults. MRI guided placement of electrodes also has safety implications because the radiofrequency (RF) fields used for exciting the signal in MRI can cause uncontrolled currents to flow in implanted wires, producing local heating and tissue damage. Currently special constraints must be placed on the wires and scanner operation to mitigate this risk.
The project will address key needs for pediatric neurostimulator placement and planning by deploying a common core of electromagnetic simulation and RF design. First, it seeks to explore systematic safety solutions for electrode placement under real time MRI guidance using the emerging platform technology approach of Parallel Transmit (PTx). It has recently been shown that PTx can make MRI systematically safe without the need to compromise performance by actively ensuring minimal currents flow on any wires present (DOI:10.1002/mrm.25543). We have demonstrated that PTx can also safely visualize the exact wire locations (Padormo et al proc ISMRM 2016). The student will investigate PTx approaches for systematically safe MRI guided neurostimulator placement, including candidate designs for RF coils, required sensors, and imaging methodology. Verification on test phantoms will be performed on our existing PTx research 3T scanner.
The other key challenge is to visualize the precise locations and contextual anatomy in individual patient brains’ prior to surgery planning. Ultrahigh field MRI (7T) has been shown to provide clear delineation of deep grey nuclei and at higher resolution (DOI:10.1002/ima.20143). However, there has been little or no work on visualizing these nuclei in the pediatric brain, or on imaging pediatric subjects at 7T in general. The student will apply EM simulation methods to determine safe and efficient operating regimes for pediatric brain imaging at 7T, including use of PTx.
A core of the project will involve electromagnetic simulation of coils and electrodes placed within digital human phantoms. Strength in maths, physics and simulation will be highly advantageous.
The project is funded by the UK Medical Research Council CASE studentship scheme in collaboration with an industrial partner, Rapid Biomedical, who supply and develop RF technology, particularly array coils to the MR sector. The studentship will be aligned with the EPSRC Centre for Doctoral Training (CDT) in Medical Imaging at KCL/ICL).
Funding Notes
The studentship comes with a stipend, which is available for UK Students, and EU students who have lived, worked or studied within the UK for 3 years prior to the funding commencing.