Characterizing gradient performance and estimating Maxwell fields at 0.55T.

In this work we use a general sequence to characterize gradient imperfections at low field (0.55T) by measuring the gradient impulse response function (GIRF). Maxwell fields become non-negligible at lower field strengths and so we incorporate these into our GIRF calculation to form a single processing pipeline. Once the predictive ability of the GIRF was confirmed, we use our data to estimate the Maxwell phase and compare this to an analytic approach; good agreement is observed. These results will inform future low-field investigations and enable an improved image quality for sequences that are particularly prone to gradient imperfections.