Fig. 1.

a High-frequency current passes through cells and low-frequency current flows through only the extracellular space. b We may express mobility of a charge carrier in free motion as a scalar or isotropic tensor variable and in restricted or hindered motions as an anisotropic tensor variable. The electrical conductivity is, therefore, expressed as a scalar quantity at high frequency and a tensor quantity at low frequency. c Conductivity tensor images are reconstructed from two separate scans of B1 mapping and multi-b diffusion weighted imaging. d The high-frequency conductivity image is reconstructed from the B1 map. e–g The variables associated with mobility and volume fraction are extracted from the multi-b data sets. h, i These are combined to produce the conductivity tensor image