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Numerical optimization of a three‐channel radiofrequency coil for open, vertical‐field, MR‐guided, focused ultrasound surgery using the hybrid method of moment/finite difference time domain method
Author(s) -
Xin Xuegang,
Wang Di,
Han Jijun,
Feng Yanqiu,
Feng Qianjin,
Chen Wufan
Publication year - 2012
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1811
Subject(s) - finite difference time domain method , radiofrequency coil , electromagnetic coil , acoustics , moment (physics) , physics , electromagnetic field , finite difference method , nuclear magnetic resonance , optics , computer science , classical mechanics , quantum mechanics , thermodynamics
The numerical optimization of a three‐channel radiofrequency (RF) coil with a physical aperture for the open, vertical‐field, MR‐guided, focused ultrasound surgery (MRgFUS) system using the hybrid method of moment (MoM)/finite difference time domain (FDTD) method is reported. The numerical simulation of the current density distribution on an RF coil with a complicated irregular structure was performed using MoM. The electromagnetic field simulation containing the full coil–tissue interactions within the region of interest was accomplished using the FDTD method. Huygens' equivalent box with six surfaces smoothly connected the MoM and FDTD method. An electromagnetic model of the human pelvic region was reconstructed and loaded in the FDTD zone to optimize the three‐channel RF coil and compensate for the lower sensitivity at the vertical field. In addition, the numerical MoM was used to model the resonance, decoupling and impedance matching of the RF coil in compliance with engineering practices. A prototype RF coil was constructed to verify the simulation results. The results demonstrate that the signal‐to‐noise ratio and the homogeneity of the B 1 field were both greatly improved compared with previously published results. Copyright © 2011 John Wiley & Sons, Ltd.