中国物理B ›› 2014, Vol. 23 ›› Issue (2): 28703-028703.doi: 10.1088/1674-1056/23/2/028703

• INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY • 上一篇    下一篇

Multi-objective optimization of gradient coil for benchtop magnetic resonance imaging system with high-resolution

王龙庆, 王为民   

  1. Institute of Quantum Electronics, School of Electronic Engineering and Computer Science, Peking University, Beijing 100871, China
  • 收稿日期:2013-04-15 修回日期:2013-05-03 出版日期:2013-12-12 发布日期:2013-12-12
  • 基金资助:
    Project supported by the Natural Science Foundation of the Ministry of Science and Technology of China (Grant No. 2011ZX05008004) and the Science Fund of the Committee of Science and Technology of Beijing, China.

Multi-objective optimization of gradient coil for benchtop magnetic resonance imaging system with high-resolution

Wang Long-Qing (王龙庆), Wang Wei-Min (王为民)   

  1. Institute of Quantum Electronics, School of Electronic Engineering and Computer Science, Peking University, Beijing 100871, China
  • Received:2013-04-15 Revised:2013-05-03 Online:2013-12-12 Published:2013-12-12
  • Contact: Wang Wei-Min E-mail:wmw@pku.edu.cn
  • About author:87.61.-c; 84.32.Hh; 02.30.Zz
  • Supported by:
    Project supported by the Natural Science Foundation of the Ministry of Science and Technology of China (Grant No. 2011ZX05008004) and the Science Fund of the Committee of Science and Technology of Beijing, China.

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摘要： Significant high magnetic gradient field strength is essential to obtaining high-resolution images in a benchtop magnetic resonance imaging (BT-MRI) system with permanent magnet. Extending minimum wire spacing and maximum wire width of gradient coils is one of the key solutions to minimize the maximum current density so as to reduce the local heating and generate higher magnetic field gradient strength. However, maximum current density is hard to optimize together with field linearity, stored magnetic energy, and power dissipation by the traditional target field method. In this paper, a new multi-objective method is proposed to optimize the maximum current density, field linearity, stored magnetic energy, and power dissipation in MRI gradient coils. The simulation and experimental results show that the minimum wire spacings are improved by 159% and 62% for the transverse and longitudinal gradient coil respectively. The maximum wire width increases from 0.5 mm to 1.5 mm. Maximum gradient field strengths of 157 mT/m and 405 mT/m for transverse and longitudinal coil are achieved, respectively. The experimental results in BT-MRI instrument demonstrate that the MRI images with in-plane resolution of 50 μm can be obtained by using the designed coils.

关键词: magnetic resonance imaging, gradient coil, target field method, wire spacing

Abstract: Significant high magnetic gradient field strength is essential to obtaining high-resolution images in a benchtop magnetic resonance imaging (BT-MRI) system with permanent magnet. Extending minimum wire spacing and maximum wire width of gradient coils is one of the key solutions to minimize the maximum current density so as to reduce the local heating and generate higher magnetic field gradient strength. However, maximum current density is hard to optimize together with field linearity, stored magnetic energy, and power dissipation by the traditional target field method. In this paper, a new multi-objective method is proposed to optimize the maximum current density, field linearity, stored magnetic energy, and power dissipation in MRI gradient coils. The simulation and experimental results show that the minimum wire spacings are improved by 159% and 62% for the transverse and longitudinal gradient coil respectively. The maximum wire width increases from 0.5 mm to 1.5 mm. Maximum gradient field strengths of 157 mT/m and 405 mT/m for transverse and longitudinal coil are achieved, respectively. The experimental results in BT-MRI instrument demonstrate that the MRI images with in-plane resolution of 50 μm can be obtained by using the designed coils.

Key words: magnetic resonance imaging, gradient coil, target field method, wire spacing

中图分类号:  (Magnetic resonance imaging)

  • 87.61.-c
84.32.Hh (Inductors and coils; wiring) 02.30.Zz (Inverse problems)