Analysis of local projected current density from one component of magnetic flux density in MREIT

• Published in: Inverse problems Vol. 29; no. 7; pp. 75001 - 17
• Main Authors: Kim, Hyung Joong, Sajib, Saurav Z K, Jeong, Woo Chul, Kim, Myoung Nyoun, Kwon, Oh In, Woo, Eung Je
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.07.2013
• Subjects: Algorithms; Current density; Density; Imaging; Injection current; Magnetic flux; Mathematical models; Noise; Texts
• ISSN: 0266-5611; 1361-6420
• DOI: 10.1088/0266-5611/29/7/075001

Magnetic resonance electrical impedance tomography is a new modality capable of imaging the static electrical conductivity of an object by measuring Bz data, a component of the magnetic flux density B = (Bx, By, Bz), perturbed by an external injection current. In an imaging area, the current density J induced by the external injection current can be uniquely decomposed into a recoverable component JP and an invisible component from the measured Bz data. In the case of in vivo animal and human imaging experiments, the imaging area frequently includes local defective regions with a low signal-to-noise ratio. As a result, the measured Bz data in the defective regions include serious noise due to rapid T2 decay, a small amount of internal current density and weak MR signals. In this paper, we propose an algorithm to reconstruct a recoverable current density from the measured Bz data in a local region avoiding the defective regions. We estimate the L2-norm of the difference between the induced internal current density J and the locally recovered from the measured Bz data in the local region . The difference only depends on the z-components of J and J0 and the values of Bx and By on the boundary , where J0 is the background current density by the injected current. Numerical simulations and phantom experiments demonstrate that the proposed method directly reconstructs a local current density avoiding noise effects in defective regions.