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RF B 1 field localization through convex optimization
Author(s) -
Olson Chris,
Yoo Hyoungsuk,
Delabarre Lance,
Vaughan J.Thomas,
Gopinath Anand
Publication year - 2012
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.26456
Subject(s) - human head , imaging phantom , antenna (radio) , finite difference time domain method , microwave , physics , field (mathematics) , phase (matter) , radio frequency , optics , mathematics , electronic engineering , engineering , electrical engineering , quantum mechanics , pure mathematics , absorption (acoustics)
A 9‐cm wavelength in the human brain at the 400‐MHz Larmor frequency for 9.4‐T leads to pronounced B 1 field contours and consequential image inhomogeneity. The objective of this study was to develop a new technique to control this nonuniformity by designing the phase and magnitude of radiofrequency (RF) power emanating from RF coil antenna elements in a multichannel transceiver array. Nonuniformity was used to steer a constructively interfering B 1 field node to spatially correlate with an anatomic region of interest. This work outlines a convex (quadratically constrained quadratic problem) formulation of the B 1 localization problem and the benefits of such a formulation. This convex formulation was used to design antenna excitation magnitude and phase. Localization is demonstrated in simulated finite difference time domain (FDTD) B 1 field human head distributions and human head phantom measurement. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:31–37, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26456
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