MRI and Quantum Physics

MRI and Quantum Physics

Dr Timothy Stait-Gardner

National Imaging Facility Fellow and Post Doctoral Fellow at UWS. 

Qualifications:

BSc (Honours, Class 1) with major in Physics and sub major in Mathematics, PhD, Theoretical Physics (UWS). 

Short Biography:

  • 2006 – I joined  the Nanoscale Organisation and Dynamics Group and began research in NMR/MRI pulse sequence development and theory, particularly in relation to the development of fast diffusion sequences.
  • I co-supervise PhD and Honours students:
      • Abhishek Gupta - PhD
      • Amninder Virk - PhD
      • Ben Moroney – PhD
      • Dale Codling - PhD
      • Ryan Dean – PhD
      • Yanurita Dwi Hapsari – PhD
  • I have given Tutorials in the following
      • 1st Year Nanotechnology II
      • 2nd Year Quantum Properties of Chemical Systems
      • 3rd Year Fabrication of Nanomaterials  
  • 2002 – 2006 –  My PhD involved both general relativity and quantum mechanics to show that there are fundamental differences between the Unruh effect and Hawking radiation. My thesis also incorporated work on spin physics which was later directly applicable to research conducted in the field of Nuclear Magnetic Resonance (NMR).
  • 2000 – 2003 – I worked as part of the Fusion Research Group at the University of Western Sydney which studied laser confinement, where I examined the form of the electromagnetic field of Laguerre-Gaussian beams.

Awards & Scholarships:

  • UWS Symposium & Workshop on NMR Imaging and Diffusion 2006 Best Poster Prize
  • New South Wales Australian Institute of Physics Prize (Best Honours Student 2001)
  • The Australian Postgraduate Award (2001-2004)

National Imaging Facility (NIF)

National Imaging Facility (opens in a new window) provides state-of-the-art very high resolution magnetic resonance imaging (MRI) of animals, plants and materials for the Australian research community. NIF's grid of imaging facilities with nodes in New South Wales, Queensland, South Australia and Victoria provide a range of leading-edge imaging instrumentation and advice and assistance in the optimal use of imaging to the research community.

As the Facility Fellow at the UWS node of the NIF, I oversee external use of the 11.7 T MRI and 7 T Animal MRI located respectively at UWS's Campbelltown and Hawkesbury campuses.     

Examples of Projects carried out by NIF can be found through NIF Projects (opens in a new window).

Past & Present Collaborations: 

Brain and Mind Research Institute - 2011 - ongoing
This collaboration is a study of the effect of stress on the brain. We are taking very high resolution images of mice brains using MRI and our collaborators are quantifying gray matter loss.

CSIRO - 2011 - ongoing
This collaboration involves the study of supra-molecular nanoparticle based T1 contrast agents on live mice. I co-supervised an honours student who synthesises the nanoparticles and conducts NMR experiments to determine how they affect relaxation. The student is continuing this research project for their PhD.

National Wine and Grape Research Centre - 2010 - ongoing
This collaboration is a wide ranging investigation of the application of MRI to grapes and viniculture and viticulture in general. Our research currently involves is the characterisation of Shiraz berries in various stages of development using MRI including diffusion weighted and diffusion tensor techniques.
We hope to be able to determine the underlying causes of berry split in Shiraz berries. A PhD student is also currently working on this project.

UWS Medical School - 2010 - ongoing
This collaboration is on the flow of blood in the placenta with the aim of studying preeclampsia. Preeclampsia is a medical condition which occurs during pregnancy and is diagnosed when hypertension arises.
This project has resulted in (to our knowledge) the first ever MRI image of a mouse umbilical cord.

University of Sydney Medical School - 2006 - ongoing
Collaborating with Dr Roger Bourne of Sydney University, we have obtained images at 11.7 T of diseased human tissue with resolution an order of magnitude greater than that obtainable from a hospital grade MRI. A new NHMRC grant awarded in 2011 ensures that this research will continue.  

Prince of Wales Hospital via UNSW - 2008 - 2011
This collaboration is with the Oncology Research Centre at the PoW Hospital. The collaboration involves the study of nanoparticle-based contrast agents (such as iron oxide nanoparticles and gadolinium nanoparticles) for detecting tumours.

UNSW via UWS Medical School - 2006 - 2009
With this collaboration we have been looking at the mechanical properties of skin (opens in a new window) (PDF, 1045KB).

Centre for Plant and Food Science (PAFS) - 2006 - 2007
From October 2006 until March 2007 I worked in collaboration with the PAFS on a project investigating whether inorganic phosphorus (31P) regulates the rate of leaf photosynthesis and growth during phosphorus starvation.

Many of the images produced of fruit with the 11.7 T spectrometer have appeared in official UWS publications, a number of presentations and appear in a video circulated among local schools.

Research Interests:

Intermolecular dipolar coupling
The physics of intermolecular dipolar coupling between molecules separated by macroscopic distances and the observable effects of such couplings during specially tailored NMR experiments. These long-range dipolar couplings may account for some anomalous variations in the measured diffusion coefficient when the SS-PGSE experiment (opens in a new window) (PDF, 499Kb) is run very quickly. A thorough investigation of the effects of intermolecular multiple quantum coherences may allow significant improvements to sequences like SS-PGSE resulting in new very fast, accurate and precise diffusometry techniques. In addition I believe there is a vast range of untapped potential applications for intermolecular dipolar couplings.

NMR pulse shaping and theoretical techniques
I am interested in pulse shaping in NMR, particularly with regard to genetic algorithmic methods. It is very straightforward to go from a shaped RF pulse which can be both frequency and amplitude modulated to the resulting excitation profile but the reverse is more difficult—finding the RF pulse shape needed to give a particular excitation profile. The problem is almost perfect for solution using genetic algorithms which fits under the evolutionary engineering umbrella although surprisingly such a technique has not yet been utilised.
 
Diffusion
Diffusion for a number of reasons. Specially tailored NMR sequences (PGSE and PGSTE) can be used to determine the diffusion coefficient of molecules in solution and hence can be used as a means to assign resonances to molecules in a mixture. The technique works when the mixture has only a few species of significantly different diffusion coefficient but does not perform well in other situations. NMR diffusion measurements can also be used, among other things, to examine the binding of drugs to proteins, which is the primary means of drug action. Diffusion measurements are quite slow and can sometimes take many hours.

The possibility of speeding up diffusion measurements significantly while still retaining other information such as chemical shifts is extremely exciting. Such fast diffusion sequences will not only allow for much more efficient use of NMR spectrometers but will also extend the application of diffusion measurements into previously inaccessible time domains. Current diffusion measurements start from a static equilibrium and their speed is limited by the need to wait for equilibrium after each scan before a new scan can begin. I am looking at the possibility of creating a well-defined dynamic equilibrium reducing or eliminating the need to wait for full relaxation after each scan. A number of difficulties arise such as the effects of multiple quantum coherence's and the possibility of distant dipolar couplings which make this far from straightforward and connect this work to my other interest in intermolecular dipolar couplings.

Computer methods
The construction of symbolic algebra systems and numerical simulations for use in NMR pulse sequence design is an extremely important part of pulse sequence design. I have long had an interest in the application of computers to solving physical problems or running simulations of complex physical systems intractable to an analytical approach. My current intention is to write a symbolic algebra package which will add the ability to model intermolecular dipolar couplings to the product operator description of NMR experiments. This will, of course, greatly facilitate my research into the effects of intermolecular dipolar couplings.