1. A method for identifying the relative contributions of signals of a first substance and a second substance in a magnetic resonance (“MR”) image, the method comprising: selecting an image signal model; selecting a scan parameter; forming a bias field estimate; applying a bias correction to a phase image; estimating the signal fraction of the first substance and the second substance at each of a plurality of voxels; and forming a suppressed image with respect to the first substance or the second substance.