Patent ID: 7141972
Filing Date: 2006-11-28
Classification: G01R

Abstract:
1. A method for magnetic resonance imaging of a object in which two moieties of differing chemical shifts are separated in presence of a non-uniform magnetic field, said method comprising: positioning the object to be imaged in a magnetic resonance imaging (MRI) device; acquiring at least three sets of MRI data of the object by applying a series of fast spin echo (FSE) sequences in which a readout gradient waveform is shifted to produce at least three sets of MRI data that are similarly spatially encoded, wherein the FSE sequences have different signal timing to produce three different phase shifts between two chemically shifted signals w and f in the MRI data sets, and wherein one of the MRI data sets has a phase difference (α generating at least three complex image data sets by reconstructing images from the at least three MRI data sets; using the at least three complex image data sets two at a time to generate two pairs of solutions for separate images of w and f signals having different chemical shifts, the solutions are generated according to equation A below: where α is an induced phase shift between the w and f signals; from the two pairs of solutions for w and f and from equations B and C which are: determining two pairs of solutions ({β 1 1 , β 1 2 } and {β 2 1 , β 2 2 }) for a main magnetic field inhomogeneity (β) wherein the solution {β 1 1 , β 1 2 } is determined using the in-phase MRI data set and an MRI data set having the largest phase shift (α n1 ), and the solution {β 2 1 , β 2 2 } is determined using the in-phase MRI data set and an MRI data set having another the second largest phase shift (α n2 ); determining a unique solution for β from {β and applying the selected β to determine a final result solution for at least one of the w and f signals.