1. A method for determining a concentration of fat within a region of a subject, comprising: acquiring at least three gradient echo images e 1 , e 2 , and e 3 of a region of a subject from at least two different flip angles α 1 and α 2 within a repetition time TR for a total of at least six gradient echo images e 1 α 1 , e 2 α 1 , e 3 α 1 , e 1 α 2 , e 2 α 2 , and e 3 α 2 , wherein gradient echo images e 1 α 1 , e 1 α 2 , e 3 α 1 , and e 3 α 2 occur at an in-phase time when resonance signals of fat and water are in-phase with one another and gradient echo images e 2 α 1 , and e 2 α 2 occur at an opposed-phase time when the resonance signals of fat and water are 180° out of phase with one another; approximating a T2* relaxation time map from the in-phase gradient echo images based on the α 1 flip angle or the α 2 flip angle; approximating a T1 relaxation time map from the in-phase gradient echo images based on the α 1 flip angle and the α 2 flip angle; distinguishing between fat and water signals within the gradient echo images based on observed relative signal phase; modulating the amplitude of the fat and water signal images using the T2* relaxation time and T1 relaxation time maps; determining a ratio between fat and water signals for one or more voxels of the gradient echo images based on the amplitude modulated fat and water signal images; and displaying the deter mined ratio between fat and water for a desired voxel of the gradient echo images.