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Virtual frequency encoding: Achieving symmetry in k ‐space
Author(s) -
Hinks R. Scott,
Derbyshire J. Andrew,
Leroux Patrick L.
Publication year - 1998
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910390622
Subject(s) - encoding (memory) , encode , physics , swap (finance) , computer science , phase (matter) , signal (programming language) , nuclear magnetic resonance , algorithm , topology (electrical circuits) , artificial intelligence , chemistry , mathematics , quantum mechanics , biochemistry , finance , economics , combinatorics , gene , programming language
Chemical shift artifacts and other off‐resonance spatial shifts in 2DFT MRI arise from the linear time dependence in the k ‐space data in the readout direction. Introduction of a view‐dependent time shift of the readout window adds a time dependence to the phase‐encoding direction and results in a virtual frequency‐encoding direction that is a linear combination of the phase‐encode and readout axes. By this method, the readout and phase‐encode directions can be made identical in their sensitivity to off‐resonance effects and can be arbitrarily swapped with no change in chemical shift or inhomogeneity effects, improving previously reported methods that swap these axes for signal averaging or reduction of motion artifacts.