Correction of Gradient Echo Images for First and Second Order Macroscopic Signal Dephasing Using Phase Derivative Mapping

Hendrik de Leeuw¹, Chris J.G. Bakker¹

Gradient Echo MRI is frequently applied for its inherent sensitivity to mesoscopic field inhomogeneities, which reflect local tissue properties. Unfortunately, macroscopic field inhomogeneities, such as inhomogeneities invoked by air cavities, interfere with the mesoscopic effects. Compensation methods typically lack flexibility (need precise, object dependent, scan adjustments), lengthen data acquisition (additional reconstructions, acquisitions) or is not generally applicable (multi-echo only). Herein a generally applicable (single, multi-echo) post-processing method is presented which compensates for first and second order macroscopic phase incoherences, while preserving mesoscopic effects. The method is demonstrated on a phantom containing mesoscopic field disturbers and the head of a volunteer.