title: Local harmonic B(z) algorithm with domain decomposition in MREIT: computer simulation study.
abstract: Magnetic resonance electrical impedance tomography (MREIT) attempts to provide conductivity images of an electrically conducting object with a high spatial resolution. When we inject current into the object, it produces internal distributions of current density and magnetic flux density. By using a magnetic resonance imaging (MRI) scanner, we can measure B(z) data where z is the direction of the main magnetic field of the scanner. Conductivity images are reconstructed based on the relation between the injection current and B(z) data. The harmonic B(z) algorithm was the first constructive MREIT imaging method and it has been quite successful in previous numerical and experimental studies. Its performance is, however, degraded when the imaging object contains low-conductivity regions such as bones and lungs. To overcome this difficulty, we carefully analyzed the structure of a current density distribution near such problematic regions and proposed a new technique, called the local harmonic B(z) algorithm. We first reconstruct conductivity values in local regions with a low conductivity contrast, separated from those problematic regions. Then, the method of characteristics is employed to find conductivity values in the problematic regions. One of the most interesting observations of the new algorithm is that it can provide a scaled conductivity image in a local region without knowing conductivity values outside the region. We present the performance of the new algorithm by using computer simulation methods.
authors.affiliation: Department of Mathematics, Yonsei University, Seoul 120-749, Korea.
authors.forename: Jin Keun
authors.initials: JK
authors.lastname: Seo
authors.forename: Sung Wan
authors.initials: SW
authors.lastname: Kim
authors.forename: Sungwhan
authors.initials: S
authors.lastname: Kim
authors.forename: Ji Jun
authors.initials: JJ
authors.lastname: Liu
authors.forename: Eung Je
authors.initials: EJ
authors.lastname: Woo
authors.forename: Kiwan
authors.initials: K
authors.lastname: Jeon
authors.forename: Chang-Ock
authors.initials: CO
authors.lastname: Lee
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D017097:Electric Impedance; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008954:Models, Biological; D019047:Phantoms, Imaging; D010992:Plethysmography, Impedance / Q000379:methods