Large Field-of-View Transmission Line Resonator for High Field MRI

Transmission line resonators is often a preferable choke for coils in high field magnetic resonance imaging (MRI), because they provide a number of advantages over traditional loop coils. The size of such resonators, however, is limited to shorter than half a wavelength due to high standing wave ratio, which leads to inhomogeneous field distribution along the resonator. In this work, it is demonstrated that the resonator length can be extended to over half a wavelength with the help of series capacitors. The approach allows for reduced standing wave ratio and improved field homogeneity. Achieved magnetic field distribution is compared to the conventional transmission line resonator. Imaging experiments are performed using 7 Tesla MRI system. The developed resonator is useful for building coils with large field-of-view.