Functional Neuroimaging at Ultra-High Magnetic Field.

Functional magnetic resonance imaging (fMRI) is widely used to study brain function. Most fMRI is carried out in magnets of 1.5T or 3T field strength. However, we will shortly be taking delivery of the first 7T MRI scanner in Europe. It will improve substantially the sensitivity of fMRI and open up exciting new areas of research. For instance, instead of studying repeated trials of an event, the increased sensitivity will allow us to study a single trial. This will make it possible to undertake studies of learning and of isolated events such as hallucinations, as well as of the response of the brain to pharmaceutical agents. The increased sensitivity will also be used to produce extremely high resolution images, allowing us to study detailed brain anatomy in vivo. In addition,we will be able to make new and more precise measurements of blood flow and volume, and also metabolism in the brain. This will help us to understand the mechanisms that underpin brain function, enabling us to develop the quantitative MR measures of brain activity that are essential if fMRI is to realise its full potential. However MRI at 7T will not be straightforward, and so we must develop new equipment and methods to exploit the potential of ultra-high magnetic field. We will also develop new methods of analyzing data for single trial and high resolution fMRI. The advantages of 7T will be exploited in studies of hearing, the control of movement and mental disorders, such as schizophrenia.

Through the University we are involved in many outreach and access activities. We give talks to schools, host visits by school children and contribute to schemes aimed at widening University access. We give talks to interested members of the public arranged through professional bodies or directly with local clubs and interest groups. We participate in the Researchers in Residence Scheme, where research scientists are placed in schools. Our web site is accessible to the general public: currently it includes resources for schools, the general public, MR specialists and other scientists. We use the normal scientific channels to disseminate our results, but our links to MR system manufacturers, and other collaborators ensure the transfer of our ideas to a wider user community. We train many research students, and our research informs our undergraduate teaching.

The main thrust of our future development programme will be directed towards functional magnetic resonance imaging at ultra-high magnetic field (7T). These developments will bring unique advantages once the technical challenges involved in scanning at 7T have been addressed. In particular the significantly increased intrinsic signal to noise ratio, along with the enhanced BOLD (blood oxygenation level dependent) contrast at 7T, are expected to yield large gains in BOLD contrast to noise ratio (CNR). These gains will be of particular benefit to event related fMRI, where the sensitivity of single trial paradigms will be greatly enhanced. This will extend the use of fMRI to the study of unique cognitive events, and open up new opportunities for investigating learning, attention and unpredictable events, such as auditory hallucinations, as well as allowing improved monitoring of changes in brain function during pharmacological intervention. The increased CNR will also be used to improve the spatial resolution with which functional domains can be mapped. Our overall aim is to develop a 7T MR facility that maximises the benefits of ultra-high field for functional neuroimaging. To achieve this we will develop novel, specialised radiofrequency, gradient and shim coils, along with acquisition strategies that maximise functional CNR, whilst minimising susceptibility effects and the impact of physiological noise. Quantitative MRI and MRS measures of brain activity based on the haemodynamic and metabolic responses to it, as well as MRI direct detection methods, will be developed. Simultaneous EEG/fMRI and parallel MEG/fMRI studies will be undertaken to identify and improve understanding of the relationship between functional and spontaneous brain networks. We will optimise data acquisition and, in collaboration with FMRIB, data analysis methods, for single trial fMRI. The advantages of 7T will be exploited in studies of audition, sensorimotor function and mental disorders.