Spatially Selective RF Quadratic Fields Excitation

Yi-Cheng Hsu¹, I-Liang Chern¹, Fa-Hsuan Lin², ³

Using one single transmitter and quadratic magnetic fields, we propose the spatially selective RF quadratic field excitation (QEF) to 1) efficiently excite small FOV and 2) to generate a distribution of Mxy to compensate the B1 inhomogeneity in high field MRI. Specifically, compared to using linear gradients and 25 spokes, QFE is more than 2 times faster to complete the 1/3 FOV excitation with the improved accuracy of the excitation profile by 2.2-fold. In addition, QFE is 2.5 times faster than fast-Kz to excite a slice with in-plane circular symmetric flip angle distribution complementary to high field B1 inhomogeneity.