Abstract: A shimming magnetic field control (22) causes shimming magnetic fields for improving uniformity of a main magnetic field generated by main magnets (10). A resonance excitation control (32) selectively applies a resonance excitation pulse (34) and inversion pulse (36) for inverting the spin magnetization of water and lipid dipoles. A phase sensitive detector (30) selectively receives resonance signal components which are transformed by a transform algorithm (70) into a real image (72) and an imaginary image (74). The inversion pulse (36) is shifted by a time such that the water and lipid spin magnetizations are out of phase by a predetermined amount. With a 90.degree. phase difference, the real image represents water and the imaginary represents lipid. A phase image (80) is derived from a reference image pair (76, 78). A phase unwrap circuit (82) removes ambiguities attributable to the spin magnetizations becoming dephased by multiples of 2.pi. to create a phase map (84).