Estimation of the Anisotropy of Electric Conductivity via B1 Mapping

Introduction: The electric conductivity can potentially be used as diagnostic information due to its ability to reflect the grade of tissue damage (see, e.g., [1]). In its general form, the conductivity is given by a rank-2 tensor, including anisotropic cases of conductivity. In vivo, anisotropic conductivities can be found in tissue with preferred cell direction, e.g., in muscles and nerves [2]. Measuring anisotropy of the tissue conductivity, characterizing the underlying cell structure, might increase diagnostic information. The recently presented “Electric Properties Tomography” (EPT) is able to determine tissue conductivity in vivo by post-processing B1 maps [3]. This study investigates the ability of EPT to estimate also the anisotropy of the conductivity. Theory: Tissue conductivity σ and permittivity ε can be estimated via [3] (H/E the magnetic/electric field, ω the Larmor frequency)