UHF probes for functional MRI: optimisation of performance for human brain imaging at 300 MHz

Principal Investigator: Dr P M Glover (Sch of Physics & Astronomy )

Starts: 1 March 2004
Ends: 30 June 2007

Value: £237,635

Magnetic Resonance Imaging systems directed towards advancing our understanding of brain function are now being developed at operating static magnetic field strengths of 7 Tesla and above, corresponding to a proton resonant frequency of over 300 MHz. At these high frequencies, a number of hitherto ignored effects dominate the performance of the transmitter and receiver probes. These include: dielectric effects (losses and tuning stability), wavelength effects (phase retardation) and radiative losses. In general these effects lead to RF inhomogeneities within the head and therefore poor imaging performance. This research aims to develop an understanding of these problems which will inform the design of a range of probes to compensate for these effects. Numerical (Transmission Line Modelling) and analytic techniques will be employed to model the head-probe interactions for a range of probe types including TEM probes, surface coils and multi-coil arrays. Novel designs which exploit the short wavelength will also be explored. A range of optimised probes (some specifically designed for the SENSE technique) will be developed and tested with the goal of delivering the signal-to-noise ratio performance necessary for single shot functional imaging paradigms.