Experimental validations of in vivo human musculoskeletal tissue conductivity images using MR‐based electrical impedance tomography

Abstract

Magnetic resonance (MR)-based electrical impedance tomography (MREIT) is a widely used imaging technique that provides high-resolution conductivity images at DC or below the 1 kHz frequency range. Using an MR scanner, this technique injects imaging currents into the human body and measures induced internal magnetic flux density data. By applying the recent progress of MREIT techniques, such as chemical shift artifact correction, multi-echo pulse sequence, and improved reconstruction algorithm, we can successfully reconstruct conductivity images of the human body. Meanwhile, numerous studies reported that the electrical conductivity of human tissues could be inferred from in vitro or ex vivo measurements of different species. However, in vivo tissues may differ from in vitro and/or ex vivo state due to the complicated tissue responses in living organs. In this study, we performed in vivo MREIT imaging of a human lower extremity and compared the resulting conductivity images with ex vivo biological tissue phantom images. The human conductivity images showed unique contrast between two different types of bones, muscles, subcutaneous adipose tissues, and conductive body fluids. Except for muscles and adipose tissues, the human conductivity images showed a similar pattern when compared with phantom results due to the anisotropic characteristic of muscle and the high conductive fluids in the adipose tissue.

Electrical conductivity-based contrast imaging for characterizing prostatic tissues: in vivo animal feasibility study

“…The difference is even more pronounced in the peripheral zone. This cellular environment is one factor for determining electrical tissue conductivity that can be represented as a macroscopic image with novel contrast [18, 20, 21].…”

“…Specifically, the magnetic flux density information was determined by subtracting the two datasets with positive and negative currents. And the final low-frequency conductivity was reconstructed from the measured magnetic flux density by applying the projected current density method [20]. The detailed image reconstruction for conductivity was described in the work of Sajib et al [21].…”

MR‐Based Electrical Conductivity Imaging of Liver Fibrosis in an Experimental Rat Model

“…To reconstruct the electrical conductivity images of ex vivo and in vivo rats, the magnetic flux densities were generated by eliminating the effects of injected currents on raw datasets 20,21 . The final low‐frequency conductivity image was reconstructed from the measured magnetic flux density by applying the projected current density method 24 . The detailed image reconstruction for conductivity followed the work of Sajib et al 25 For quantitative analysis, the conductivity values were measured at the entire liver block in the phantom image.…”