1. A method of determining a susceptibility gradient map, the method comprising acquiring a magnetic resonance k-space dataset, said dataset comprising magnetic resonance echo data, and transforming the acquired k-space dataset into an image dataset wherein for a given k-space direction, the method comprises a) performing a 1D discrete Fourier transform of the image dataset along the given k-space direction, said 1D Fourier transform resulting in a set of Fourier terms, each Fourier term of said set being associated to a k-space index along the given k-space direction, b) selecting a truncation value steadily varying between −N/2 and N/2 along said k-space direction, where N is the size of the k-space dataset in said k-space direction, c) generating recursively an updated image dataset by determining the Fourier term of the set of Fourier terms which associated k-space index number corresponds to said truncation value and subtracting the determined Fourier term from an image dataset generated in an immediate previous image dataset generation step, said subtraction resulting in a new updated image dataset, d) calculating a magnitude of the new updated image dataset, e) repeating steps b) to d) with increasing or decreasing truncation value, f) calculating for the given k-space direction an echo shift from the magnitude variations between the new updated image datasets, g) calculating a susceptibility gradient along the given k-space direction from said echo shift.