Sascha Brunheim1,2, Stephan Orzada1, Soeren Johst1, Marcel Gratz1,2, Maximilian N. Voelker1, Oliver Kraff1, Martina Floeser3, Andreas K. Bitz3, Mark E. Ladd1,3, and Harald H. Quick1,2
1Erwin L. Hahn Institute for Magentic Resonance Imaging, University Duisburg-Essen, Essen, Germany, 2High Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany, 3Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
With current methods the mitigation of transmit field inhomogeneity at ultrahigh field by multi-channel RF shimming with conventional methods is relatively time consuming. This applies in particular for parallel transmit/receive in-vivo body imaging within breath-hold and during organ motion. Therefore, we propose a new technique merging fast acquired relative single channel maps and the spatial-dependent flip-angle distribution of two complementary shims to define absolute transmit coil maps for fast and accurate RF shim calculation. The performance of this technique is validated against established methods in phantom measurements and its reliability is shown in comparison to simulation data serving as reference.
