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BioMed Research International
Volume 2016 (2016), Article ID 8659298, 11 pages
http://dx.doi.org/10.1155/2016/8659298
Research Article

Development of High-Field Permanent Magnetic Circuits for NMRI/MRI and Imaging on Mice

1College of Science, North China University of Science and Technology, Tangshan 063000, China
2Shanghai Shining Global Science and Education Equipment Corporation, Ltd., Shanghai 201806, China
3Fundamental Medical College, North China University of Science and Technology, Tangshan 063000, China

Received 15 October 2015; Revised 24 January 2016; Accepted 27 January 2016

Academic Editor: Guang Jia

Copyright © 2016 Guangxin Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The high-field permanent magnetic circuits of 1.2 T and 1.5 T with novel magnetic focusing and curved-surface correction are developed. The permanent magnetic circuit comprises a magnetic yoke, main magnetic steel, nonspherical curved-surface magnetic poles, plugging magnetic steel, and side magnetic steel. In this work, a novel shimming method is proposed for the effective correction of base magnetic field () inhomogeneities, which is based on passive shimming on the telescope aspheric cutting, grinding, and fine processing technology of the nonspherical curved-surface magnetic poles and active shimming adding higher-order gradient coils. Meanwhile, the magnetic resonance imaging dedicated alloy with high-saturation magnetic field induction intensity and high electrical resistivity is developed, and nonspherical curved-surface magnetic poles which are made of the dedicated alloy have very good anti-eddy-current effect. In addition, the large temperature coefficient problem of permanent magnet can be effectively controlled by using a high quality temperature controller and deuterium external locking technique. Combining our patents such as gradient coil, RF coil, and integration computer software, two kinds of small animal Micro-MRI instruments are developed, by which the high quality MRI images of mice were obtained.