Multiple Area B1 Shimming: An Efficient, Low SAR Approach for T2-Weighted FMRI Acquired in the Visual and Motor Cortices of the Human Brain at Ultra-High Field

Pierre-Francois Van de Moortele¹, Eddie Auerbach¹, Kamil Ugurbil¹, Johannes Ritter¹

B1 heterogeneities are a major challenge at Ultra-High Field[1,2]. B1 shim techniques can mitigate those inhomogeneities but B1 Shim solutions aiming at uniform B1 over the whole brain generally result in poor RF efficiency because of large destructive interferences [3]. A strong case has been made for the need to address B1 inhomogeneities for T2-weighted fMRI at Ultra-High fields. It has been demonstrated that a multi region B1 shim is a very efficient approach to sample T2-weighted contrast in the visual and motor cortices.