MR Current Density and MREIT Data Acquisition

Magnetic resonance electrical impedance tomography (MREIT) can provide internal conductivity distributions at low frequency (below 1 kHz) induced by an external injecting current. In MREIT, we inject current I using at least one pair of electrodes into an object to produce internal current density J = (J_x, J_y, J_z) and magnetic flux density B = (B_x, B_y, B_z) in the object. An MRI scanner with its main magnetic field pointing the z direction is used to measure the induced magnetic flux density (B_z) caused by external current injection. To avoid the interaction of external current injection with MRI acquisitions, it is important to synchronize the current injection with MRI sequence. In the first part of this chapter, we will discuss the practical aspects of a successful MREIT experiment. Following a brief introduction to the experiment setup, we will then summarize various MRI sequences used for MREIT, magnetic flux density measurement, and image reconstructions for MREIT experiments.