Degenerate mode band-pass birdcage coil for accelerated parallel excitation.

Degenerate mode band-pass birdcage coil for accelerated parallel excitation. Research Abstract Details 

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Degenerate mode band-pass birdcage coil for accelerated parallel excitation. Abstract Text:

Vijayanand Alagappan,Juergen Nistler,Elfar Adalsteinsson,Kawin Setsompop,Ulrich Fontius,Adam Zelinski,Markus Vester,Graham C Wiggins,Franz Hebrank,Wolfgang Renz,Franz Schmitt,Lawrence L Wald,

An eight-rung, 3T degenerate birdcage coil (DBC) was constructed and evaluated for accelerated parallel excitation of the head with eight independent excitation channels. Two mode configurations were tested. In the first, each of the eight loops formed by the birdcage was individually excited, producing an excitation pattern similar to a loop coil array. In the second configuration a Butler matrix transformed this "loop coil" basis set into a basis set representing the orthogonal modes of the birdcage coil. In this case the rung currents vary sinusoidally around the coil and only four of the eight modes have significant excitation capability (the other four produce anticircularly polarized (ACP) fields). The lowest useful mode produces the familiar uniform B(1) field pattern, and the higher-order modes produce center magnitude nulls and azimuthal phase variations. The measured magnitude and phase excitation profiles of the individual modes were used to generate one-, four-, six-, and eightfold-accelerated spatially tailored RF excitations with 2D and 3D k-space excitation trajectories. Transmit accelerations of up to six-fold were possible with acceptable levels of spatial artifact. The orthogonal basis set provided by the Butler matrix was found to be advantageous when an orthogonal subset of these modes was used to mitigate B(1) transmit inhomogeneities using parallel excitation.

Degenerate mode band-pass birdcage coil for accelerated parallel excitation. Publishing Authors By Initials

V Alagappan,J Nistler,E Adalsteinsson,K Setsompop,U Fontius,A Zelinski,M Vester,GC Wiggins,F Hebrank,W Renz,F Schmitt,LL Wald,

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Degenerate mode band-pass birdcage coil for accelerated parallel excitation. Journal Published:

PUBLICATION TYPE: Research Support, Non-U.S. Gov

Journal: Magnetic resonance in medicine : official journal

VOLUME: 57

Page Numbers: 1148-58

Journal Abbreviation:

ISSN: 0740-3194

DAY: 3

MONTH: Jun

YEAR: 2007

Degenerate mode band-pass birdcage coil for accelerated parallel excitation. Information

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LANGUAGE: eng

NlmUniqueID: 8505245

Degenerate mode band-pass birdcage coil for accelerated parallel excitation. Keywords Mesh Terms:

KEYWORDS: Phantoms, Imaging

MESH TERMS: instrumentation

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Grant and Affiliation Information for Degenerate mode band-pass birdcage coil for accelerated parallel excitation.

AFFILIATION: AA Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA. vijay243@nmr.mgh.harvard.edu

Country: United States

AGENCY: United States NCRR

GRANT: P41 RR14075

ACRONYM: RR

MEDLINETA: Magn Reson Med

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