B1 Shimming with a Multi-Mode Travelling Wave Antenna at 9.4T

Daniel Brenner¹, Frank Geschewski¹, Jrg Felder¹, Kaveh Vahedipour¹, Tony Stcker¹, N. Jon Shah¹, ²

Travelling waves have been introduced as an alternative excitation technique for UHF MRI. Recently, the extension to multi-channel excitation was presented at 7T using dielectric fillings of the magnet bore. At 9.4T (~400MHz), to excite multiple modes without the necessity of such a dielectric filing becomes feasible. Building on initial performance measurements of the multi-mode antenna this work shows the prospects of RF shimming with the multi-mode antenna. The RF shimming is capable of reducing localised RF inhomogeneities in a phantom experiment. Though it cannot completely overcome the problem of B1 dropouts.