In recent years, the technologies based on the electrical properties (EPs) of human tissue, such as electrical impedance tomography (EIT) and magnetic resonance electrical impedance tomography (MREIT), have become one of the most popular research subjects in biomedicine. Compared with EIT and MREIT, the magnetic resonance electrical property tomography (MR-EPT) is a new technique using nondestructive EPs method. MR-EPT reconstructs the electrical conductivity and permittivity of the biological tissues based on the radio frequency field of the magnetic resonance imaging (MRI) system. It can obtain an accurate and high resolution image without current injection. In this paper, several methods for the EPs are reviewed, especially the MR-EPT. The theory, advantages and prospects of MR-EPT's are elaborated. The method of specific absorption rate (SAR) based on it is also introduced. MR-EPT is deserved further research and should be given more attention by the researchers. All this evolution based on MREPT can give new energy to the medical diagnosis.
Through magnetic resonance electrical properties tomography (MR-EPT), electrical conductivity and permittivity of biological tissues could be reconstructed based on radio frequency field of magnetic resonance imaging (MRI) system. High precision and high resolution image could be obtained without current injection. In this study, XFDTD software was used to establish a finite element model of the human breast. Simulation was delivered at the Larmor frequency of 128 MHz by a 16-channel radio frequency coil. Conductivity and permittivity of the mammary tissue was reconstructed according to the B1+ field's amplitude and phase of forward problem. Anti-noise performance of the algorithm was studied by adding noise to B1+ field. The conductivity and permittivity's average relative error between simulation results and dielectric constant was 4.71% and 11.32%, respectively. With a signal-to-noise ratio of >30 dB, the noise added would not affect imaging results. This study demonstrated that high precision and high resolution image could be obtained by MR-EPT without excitation. MR-EPT had excellent feasibility and developing potential in early detection of diseases.