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Parallel RF transmission with eight channels at 3 Tesla
Author(s) -
Setsompop Kawin,
Wald Lawrence L.,
Alagappan Vijayanand,
Gagoski Borjan,
Hebrank Franz,
Fontius Ulrich,
Schmitt Franz,
Adalsteinsson Elfar
Publication year - 2006
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21042
Subject(s) - flip angle , excitation , parallel communication , radiofrequency coil , electromagnetic coil , scanner , transmission (telecommunications) , radio frequency , pulse (music) , optics , nuclear magnetic resonance , physics , acoustics , materials science , computer science , magnetic resonance imaging , telecommunications , medicine , quantum mechanics , detector , radiology
Spatially selective RF waveforms were designed and demonstrated for parallel excitation with a dedicated eight‐coil transmit array on a modified 3T human MRI scanner. Measured excitation profiles of individual coils in the array were used in a low‐flip‐angle pulse design to achieve desired spatial target profiles with two‐ (2D) and three‐dimensional (3D) k ‐space excitation with simultaneous transmission of RF on eight channels. The 2D pulse excited a high‐resolution spatial pattern in‐plane, while the 3D trajectory produced high‐quality slice selection with a uniform in‐plane excitation despite the highly nonuniform individual spatial profiles of the coil array. The multichannel parallel RF excitation was used to accelerate the 2D excitation by factors of 2–8, and experimental results were in excellent agreement with simulations based on the measured coil maps. Parallel RF transmission may become critical for robust and routine human studies at very high field strengths where B 1 inhomogeneity is commonly severe. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.