Multipoint dixon technique for water and fat proton and susceptibility imaging

Abstract

Extensions to a previously described three‐point Dixon magnetic resonance imaging technique are presented that use alternative water/fat phase‐encoding strategies. The technique is generalized to phase encoding of (−θ,0,θ) or (0,θ,2θ) radians, and the signal‐to‐noise ratio (S/N) performance is evaluated. It was found that a θ of 2π/3 radians has optimal S/N but that a θ of π radians is a good compromise and that phase encoding of (O,π, 2π) radians offer an advantage over the previous method, which used (−π, O, π) increments, in that a T2′ (intravoxel susceptibility dephasing) image may be obtained in addition to the usual water, fat, and B 0 images. A new four‐point method with phase encoding of (O, π, 2π, 3π) radians that can also provide a measure of the spectral width of the fat resonance is suggested. The disadvantages of the method are the extra imaging time and low S/N efficiency.