A method for post-processing images of a region of interest in a subject, the images being acquired with a magnetic resonance imaging technique, the method for post-processing comprising at least the step of: unwrapping the phase of each image, extracting a real signal over echo time for at least one pixel of the unwrapped images, and calculating fat characterization parameters by using a fitting technique applied on a model, the model being a function which associates to a plurality of parameters each extracted real signal, the plurality of parameters comprising at least two fat characterization parameters and at least one parameter obtained by a measurement, the fitting technique being a non-linear least-square fitting technique using pseudo-random initial conditions.