MRI with dixon-type water/fat separation and prior knowledge about inhomogeneity of the main magnetic field

摘要

A method and an apparatus for MR imaging of at least two chemical species having different MR spectra enables Dixon water/fat separation in cases in which a large field-of-view is required. The method includes the steps of: a) generating at least one echo signal by subjecting a body placed in the examination volume of a MR device to an imaging sequence of RF pulses and switched magnetic field gradients; b) acquiring the at least one echo signal; c) separating signal contributions of the at least two chemical species to the at least one acquired echo signal on the basis of a spectral model and prior knowledge about the spatial variation of the main magnetic field Bo in the examination volume; and d) reconstructing a MR image from the signal contributions of at least one of the chemical species.