Insert Dome Gradient Coils for Brain Imaging

J. Leggett, D. Green, R. Bowtell Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom Introduction Insert gradient coils offer significant advantages for brain imaging as a result of the large increase in gradient performance that is achieved as the coil size is reduced. It has been shown previously that head-sized hemispherical gradient coils offer further improvements in performance compared with cylindrical insert coils [1], allowing very large gradients to be generated with short rise-times. However the enhanced performance is compromised when torque-balancing is incorporated into the design of transverse hemispherical coils. Here, we show how the addition of a short, cylindrical coil section to the open end of the hemisphere, overcomes this problem, allowing the design of torque-balanced gradient coils suitable for brain imaging, which have significantly higher efficiency at fixed inductance than conventional cylindrical insert coils. Using this approach, a full three-axis, dome gradient coil set has been designed, built and subsequently used in brain imaging experiments at 3 T.