THE WELLCOME TRUST HIGH FIELD MR RESEARCH LABORATORY
The scope of magnetic resonance in the neurosciences and in clinical neurology has been transformed in recent years by numerous technical and technological developments. New areas of research are opening up in functional brain imaging, and in the investigation of many disorders of the brain, including cerebral ischaemia, epilepsy, multiple sclerosis and Parkinson's disease. However, although the functional MRI results obtained using machines of standard field strength are impressive, there is nevertheless a continued drive towards improvements in temporal and spatial resolution, and higher sensitivity to small changes in signal intensity. Such improvements can now be achieved using the new generation of high field (4 Tesla or greater) systems that are becoming available.
The scientific aims of the new facility which incorporates a 90cm 4.7 Tesla research MR spectrometer are:
The specific techniques that we propose to use include
- to optimise the sensitivity of magnetic resonance to local haemodynamic changes associated with cerebral task activation and improve both temporal and spatial resolution; this is a critical requirement in the further development of functional neuroimaging with MRI to realise the full scientific potential of this method;
- to increase our understanding of the physiological mechanisms underlying these haemodynamic changes;
- to establish and optimise methods for the investigation of pathophysiological processes in brain disease.
- T2*-weighted and flow-weighted MRI for measurement of regional oxygenation status and blood flow;
- diffusion-weighted MRI, which now provides an important new contrast parameter in acute stroke, and may also prove to be of value for functional studies.
- ultra-high resolution MRI of the human brain, with magnetisation transfer contrast, allowing detailed analysis of local brain-activity-related haemodynamic changes, and possibly permitting non-invasive identification of functionally specialised areas;
- T2, T2*, and T2' measurements for the assessment of local magnetic interactions;
- localised magnetic resonance spectroscopy (MRS) for the detection of specific metabolites including GABA, glutamine and glutamate, for mapping brain temperature in brain disorders, and for the rapid measurement of blood oxygenation changes in localised brain regions.
While many of these techniques are already being used on clinical imaging systems, there is little doubt that more thorough analysis of spin physics, coupled with the higher sensitivity provided by a 4 T system, will lead to major improvements in performance, including improved signal-to-noise ratios, improved temporal, spatial and spectral resolution, and better quantification of physiological parameters. We believe that the implementation and evaluation of these techniques on a state-of-the-art 4.7 T system will lead to further important advances in the use of magnetic resonance in clinical neurology and the neurosciences. In particular, they will add greatly to the strength of existing research programmes in the Bloomsbury area in functional neuroimaging and in the investigation of cerebral hypoxia, ischaemia, and epilepsy.