Constraining the initial phase in water–fat separation

An algorithm is described for use in chemical shift-based water–fat separation to constrain the phase of both species to be equal at an echo time of zero. This constraint is physically reasonable since the initial phase should be a property of the excitation pulse and receiver coil only. The advantages of phase constrained water–fat separation, namely, improved noise performance and/or reduced data requirements (fewer echos), are demonstrated in simulations and experiments.