A method comprises digitally representing a volume of space as a plurality of voxels and assigning real and imaginary values derived from magnetic resonance imaging data of the space to each of the voxels. Furthermore, the method comprises a steps of calculating a first complex summation of the real and imaginary values of a first set of the voxels, and calculating a second complex summation of the real and imaginary values of a second set of the voxels. Each set of voxels represents a different region of the volume of space. The regions are concentric. The method also comprises steps of using the first and second summations, along with another value quantitatively calculated from the magnetic resonance imaging data, to calculate a value that is dependent upon the approximate magnetic moment of an object within the volume of space, and digitally representing and storing said value.