title: Error analysis of nonconstant admittivity for MR-based electric property imaging.
abstract: Magnetic resonance electrical property tomography (MREPT) is a new imaging modality to visualize a distribution of admittivity γ = σ+iωε inside the human body where σ and ε denote electrical conductivity and permittivity, respectively. Using B1 maps acquired by an magnetic resonance imaging scanner, it produces cross-sectional images of σ and ε at the Larmor frequency. Since current MREPT methods rely on an assumption of a locally homogeneous admittivity, there occurs a reconstruction error where this assumption fails. Rigorously analyzing the reconstruction error in MREPT, we showed that the error is fundamental and may cause technical difficulties in interpreting MREPT images of a general inhomogeneous object. We performed numerical simulations and phantom experiments to quantitatively support the error analysis. We compared the MREPT image reconstruction problem with that of magnetic resonance electrical impedance tomography (MREIT) to highlight distinct features of both methods to probe the same object in terms of its high- and low-frequency conductivity distributions, respectively. MREPT images showed large errors along boundaries where admittivity values changed whereas MREIT images showed no such boundary effects. Noting that MREIT makes use of the term neglected in MREPT, a novel MREPT admittivity image reconstruction method is proposed to deal with the boundary effects, which requires further investigation on the complex directional derivative in the real Euclidian space [Formula: see text].
authors: Department of Computational Science and Engineering, Yonsei University, Seoul 120-749, South Korea. seoj@yonsei.ac.kr
authors: Jin Keun
authors: JK
authors: Seo
authors: Min-Oh
authors: MO
authors: Kim
authors: Joonsung
authors: J
authors: Lee
authors: Narae
authors: N
authors: Choi
authors: Eung Je
authors: EJ
authors: Woo
authors: Hyung Joong
authors: HJ
authors: Kim
authors: Oh In
authors: OI
authors: Kwon
authors: Dong-Hyun
authors: DH
authors: Kim
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D017097:Electric Impedance; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008954:Models, Biological; D019047:Phantoms, Imaging; D010992:Plethysmography, Impedance / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique