====== Susceptibility artifact ======

The magnetic field distortions created by [[susceptibility]] effects result in variations in precessional frequency across the patient and even within individual voxels. These frequency changes, in turn, produce signal loss from T2*-dephasing and spatial mismapping of the MR signal.  The MR imaging characteristics reflect both of these physical mechanisms: geometric distortion with focal areas of signal void and regions of very bright signal resulting from "piling up" signal assigned to the wrong areas.