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Experimentally verified, theoretical design of dual‐tuned, low‐pass birdcage radiofrequency resonators for magnetic resonance imaging and magnetic resonance spectroscopy of human brain at 3.0 Tesla
Author(s) -
Shen Gary X.,
Wu J.F.,
Boada Fernando E.,
Thulborn Keith R.
Publication year - 1999
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/(sici)1522-2594(199902)41:2<268::aid-mrm9>3.0.co;2-g
Subject(s) - nuclear magnetic resonance , resonator , electromagnetic shielding , physics , magnetic resonance imaging , quadrature (astronomy) , materials science , optics , quantum mechanics , medicine , radiology
Abstract A new theoretical method is presented for designing frequency responses of double‐tuned, low‐pass birdcage coils. This method is based on Kirchhoff's equations through a nonsymmetric matrix algorithm and extended through a modification of the corresponding eigenvalue system from a single‐tuned mode. Designs from this method are verified for sodium/proton, dual‐tuned, double‐quadrature, low‐pass birdcage coils at 1.5 Telsa and 3.0 Tesla and then are used to design dual‐tuned, double‐quadrature, lithium/proton and phosphorus/proton birdcage coils for 3.0 Tesla. All frequencies show experimental deviations of less than 3% from theory under unloaded conditions. The frequency shifts caused by loading and radiofrequency shielding are less than 1 MHz and can be compensated readily by adjustment of variable capacitors. Applications to human neuroimaging and spectroscopy are demonstrated.Magn Reson Med 41:268–275, 1999. © 1999 Wiley‐Liss, Inc.