Synopsis

We will discuss methods to map electrical properties (EP) – conductivity and permittivity - in MRI. The methods include MR Electrical Impedance Tomography (MREIT) and Electrical Properties Tomography (MREPT), each mapping EP in a different frequency range. The first study of MREPT by Haacke in 1991, relied on the Helmholtz-wave-based formulation, but allowed limited resolution. This led to several new methods, including gradient-based EPT (gEPT) and Contrast Source Inversion EPT (CSI-EPT). New studies incorporate deep learning and demonstrate high-resolution imaging of the brain. EPT has the potential of providing new biomarkers for a range of applications and for patient-specific energy estimation.