1. A method for estimating inhomogeneities in a magnetic field of a magnetic resonance imaging (MRI) system, the steps of the method comprising: a) directing the MRI system to acquire k-space data from an imaging volume at a plurality of different echo times; b) reconstructing an image for each of the plurality of echo times using the k-space data acquired at the respective echo time; c) estimating a distribution of magnetic susceptibility values in the imaging volume using information in the images reconstructed in step b); and d) estimating a magnetic field inhomogeneity map from the distribution of magnetic susceptibility values estimated in step c).