1Department of Biometry & Medical Informatics, OvG University Magdeburg, Magdeburg, Saxony-Anhalt, Germany; 2Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Korea, Republic of
Inhomogeneous B1+ fields are still challenging at 7T. To evaluate new approaches to reduce B1+ inhomogeneity a 16-channel transmit head-array was constructed and connected to a 16x16 and an 8x8 Butler Matrix network by a pTx system with 8 RFPA for excitation. This served for sequential excitation of different circularly polarized (CP) phase modes. The CP+1 (first-order clockwise CP) as the dominant mode proved to be the most important mode to get a homogeneous image. Weighted combinations of CP+1 mode and selected clockwise higher CP modes images were found to additionally mitigate B1+ field inhomogeneity.