A computer-implemented method for post-processing images of a region of interest of the liver of a subject to obtain determined parameters, the images being acquired with a magnetic resonance imaging technique, the magnetic resonance imaging technique involving successive echoes of a multiple-gradient echo sequence, each image associating to each pixel of the image the amplitude of the measured signal in the magnetic resonance imaging technique and the phase of the measured signal in the magnetic resonance imaging technique, the method for post-processing comprising at least the step of: - obtaining in each image the heterogeneous magnetic field, the heterogeneous magnetic field being the sum of an internal magnetic field and an external magnetic field, by: - unwrapping the phase of each image, to obtain unwrapped images, - extracting the first-order phase from the unwrapped images, - calculating the heterogeneous magnetic field based on the extracted first-order phase, - separating the internal magnetic field from the external magnetic field in the heterogeneous magnetic field by: - calculating the external magnetic field by decomposing the heterogeneous magnetic field into a field generated by dipoles outside the region of interest; and - subtracting the calculated external magnetic field from the heterogeneous magnetic field using a projection onto dipole field method, to obtain the internal magnetic field, the reconstructed map being a determined parameter, - reconstructing a map of the internal magnetic susceptibility based on the internal magnetic field, the reconstructed map being a determined parameter the method being characterized in that the map of the internal magnetic susceptibility is reconstructed by using a Bayesian regularization approach to inverse the internal magnetic field. - obtaining in each image the heterogeneous magnetic field, the heterogeneous magnetic field being the sum of an internal magnetic field and an external magnetic field, by: - unwrapping the phase of each image, to obtain unwrapped images, - extracting the first-order phase from the unwrapped images, - calculating the heterogeneous magnetic field based on the extracted first-order phase, - unwrapping the phase of each image, to obtain unwrapped images, - extracting the first-order phase from the unwrapped images, - calculating the heterogeneous magnetic field based on the extracted first-order phase, - separating the internal magnetic field from the external magnetic field in the heterogeneous magnetic field by: - calculating the external magnetic field by decomposing the heterogeneous magnetic field into a field generated by dipoles outside the region of interest; and - subtracting the calculated external magnetic field from the heterogeneous magnetic field using a projection onto dipole field method, to obtain the internal magnetic field, the reconstructed map being a determined parameter, - calculating the external magnetic field by decomposing the heterogeneous magnetic field into a field generated by dipoles outside the region of interest; and - subtracting the calculated external magnetic field from the heterogeneous magnetic field using a projection onto dipole field method, to obtain the internal magnetic field, the reconstructed map being a determined parameter, - reconstructing a map of the internal magnetic susceptibility based on the internal magnetic field, the reconstructed map being a determined parameter