Jason Peter Stockmann1, Robert Todd Constable2
1Biomedical Engineering, Yale University, New Haven, CT, USA; 2Diagnostic Radiology, Neurosurgery, and Biomedical Engineering, Yale University, New Haven, CT, USA
Field mapping is typically used to map B0 inhomogeneities but there are cases where it is desireable to map the imaging gradients themselves. This work introduces a modification to conventional field mapping to widen the range of gradient strengths over which reliable field maps may be obtained. Rather than apply a constant test field over the duration of each TR, the field is pulsed through dephasing and then rephrasing lobes so as to thereby avoid the signal loss at the time t = TE. This allows shim and imaging gradient coil performance to be calibrated at strengths for which conventional field mapping is rendered inaccurate by dephasing.