Imaging the human brain using hyperpolarised xenon-129 in a PET-MR imaging system
Dr Madhwesha Rao
Prof Jim Wild
Prof Nigel Hoggard
No more applications being accepted
Competition Funded PhD Project (European/UK Students Only)
Neuropathological diseases such as stroke, tumour and dementia (Alzheimer’s diseases, MCI) alter both the perfusion in the brain and the integrity of the blood-brain barrier (BBB). Clinically, both abnormalities associated with these diseases are identified using perfusion X-ray CT or DCE MRI, although both methods poorly quantify the integrity of BBB. Another abnormality that may occur with disrupted perfusion and BBB is the irregular gas-exchange between cerebral vasculature and brain tissue. In many cases, the region of irregular gas-exchange may extend beyond the severity of the disease indicated by contemporary imaging methods like X-ray CT or MRI. The severity of regional gas-exchange that may occur with disruptive perfusion and BBB, and the impact of impaired gas-exchange on brain metabolism has not been studied well, and may provide additional insight in to the overall severity of the disease state, progression and treatment response.
Our recent studies with hyperpolarised 129Xe MRI have demonstrated a new method to directly image regional brain gas-uptake in healthy volunteers and pilot studies in stroke. In hyperpolarised 129Xe brain MRI, directly imaging the inhaled xenon dissolved in the brain tissue corroborates both the underlying regional perfusion and gas-exchange across BBB. However, recent efforts have shown that by using quantitative 1H arterial spin labelling methods, the influence of regional perfusion in 129Xe MR image(s) can be compensated such that the image contrast corresponds to regional gas-uptake across BBB. FDG-PET provides an additional unique marker of the brain metabolism, thus combined hyperpolarised 129Xe MR imaging and FDG PET imaging has the potential to uniquely characterise regional brain function.
The proposed PhD project is to further develop HP 129Xe brain PET-MRI hardware and methodology for neuropathological disease assessment through developing necessary radio frequency coils and MR pulse sequences for simultaneous multinuclear PET-MRI exams of the brain. The proposed research builds on the investigators track record with innovative imaging research and EPSRC funding, and also builds on our collaboration with GE Healthcare who have offered to enhance the stipend and provide hardware component support.
Hyperpolarised 129 Xe brain MRI is a newly developed method, demonstrated by the research group hosting this studentship, references: (a) Rao M, et al, Mag Res Med, 75-6:2227-2234, 2016, (b) Rao M, et al, Radiology, Vol. 286, No. 2, 2017 and (c) Rao M, et al, 50-3:1002-1004, 2019. Most aspects of science related to the complicated basis of image contrast and dynamics of xenon uptake in the brain is yet
to be explored and understood. Developing radio frequency coils for 129 Xe brain MRI on a PET-MRI system introduces additional RF engineering challenges such as retaining MR sensitivity when designing for PET radio-translucency. Some of the scientific challenges the PhD candidate can foresee to pursue are: (a) identify and solve RF coil engineering challenges for 129 Xe- 1 H brain MR imaging with a PET-MRI scanner, (b) introduce components that enable PET translucency, (c) establish accurate in vivo NMR properties of 129 Xe in the human brain, (c) evaluate the feasibility to quantify xenon uptake or extraction in the human brain using hyperpolarised 129 Xe brain MRI or/and (d) evaluate the feasibility to quantify regional gas-exchange using xenon uptake along with functional 1 H MRI and FDG-PET
metabolic imaging methods. The candidate is expected to be self-motivated and goal oriented.
RCUK equivalent home stipend rate per annum for 3.5 years
Home tuition fees for 3.5 years
£4,500 Research Training Support Grant
A first class or upper second class honours degree in a biological sciences subject or a related discipline, or a merit or distinction in a suitable MSc. Experience working in a research laboratory is desirable.
You should be applying to start your first year of study on a full-time or part-time PhD with the University in academic year 2020-21 (after 1 October 2020).