Magnetic field gradient imaging for material classification by magnetic resonance imaging

Issue title: Selected Papers from the 15th International Symposium on Applied Electromagnetics and Mechanics (ISEM 2011)

Article type: Research Article

Authors: Pei, Cuixiang^a | Zhu, Haitao^{a; *} | Demachi, Kazuyuki^a | Sekino, Masaki^b | Uesaka, Mitsuru^a

Affiliations: [a] Department of Nuclear Engineering and Management, The University of Tokyo, Tokyo, Japan | [b] Department of Electronic Engineering and Information System, The University of Tokyo, Tokyo, Japan

Correspondence: [*] Corresponding author: Haitao Zhu, Department of Nuclear Engineering and Management, The University of Tokyo, Tokyo, Japan. Tel.: +81 3 5841 2958; Fax: +81 3 5841 2917; E-mail: [email protected]

Abstract: In a uniform magnetic field, objects with different magnetic susceptibility may cause magnetic field distortion that can be detected by magnetic resonance imaging (MRI). Conventional MRI techniques focus on magnitude image that shows dark signals at non-uniform magnetic field. However, it is difficult to obtain the magnetic susceptibility information just from the magnitude of signal. A post-processing method is proposed to measure the magnetic field gradient induced by the sample object. Both the polarity and strength of magnetic field gradient can be calculated by this method. The method is proved by MRI experiments with paramagnetic material iron oxide particles at different concentrations, copper, and diamagnetic material graphite.

Keywords: Magnetic resonance imaging, magnetic susceptibility, echo shift, local Fourier transform

DOI: 10.3233/JAE-2012-1479

Journal: International Journal of Applied Electromagnetics and Mechanics, vol. 39, no. 1-4, pp. 335-340, 2012