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Achieving plane‐wise uniform B 1 amplitude in a 3D volume for high‐field MRI: A computer simulation study
Author(s) -
Wang Zhiyue J.,
Chu Zili
Publication year - 2006
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.20617
Subject(s) - amplitude , excitation , physics , electromagnetic coil , plane (geometry) , field (mathematics) , parallel communication , sagittal plane , acoustics , computational physics , optics , geometry , computer science , mathematics , telecommunications , transmission (telecommunications) , medicine , quantum mechanics , pure mathematics , radiology
Purpose To demonstrate the possibility of achieving plane‐wise uniform B 1 field amplitude for human head imaging with an array coil configuration by using computer simulations. Materials and Methods We considered the use of an excitation array coil that employed composite excitation elements. Each composite excitation element consisted of three small current loops centered close to each other with axes along the x, y, and z directions, respectively. The excitation elements were distributed to surround a model human head. The vector B 1 field from each current loop was calculated using the FDTD numerical method at 170 MHz. Analytical target RF field patterns with plane‐wise uniform B 1 field amplitude were derived and approximately constructed from the fields of individual current loops through a least‐squares procedure. Results The RF field patterns generated by the computer simulations closely followed the target field patterns. Highly uniform B 1 field amplitude was obtained within parallel sagittal planes or parallel axial‐to‐coronal oblique planes in the brain with the expected plane‐to‐plane variations. Conclusion In principle, patterns of B 1 amplitude distribution with a high degree of plane‐wise homogeneity can be achieved simultaneously in multiple parallel planes in a 3D volume. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.