An effect of chemical shift is that of spatial misregistration. Because the frequency displacement caused by chemical shift cannot be differentiated from intended spatial frequency encoding misregistration of the resultant signal may occur along the frequency-encoding direction.
This artifact can be seen in a FFE or SE sequence as a bright or dark band at the edge of the anatomy.
(FT) The Fourier transformation is a mathematical procedure to separate out the frequency components of a signal from its amplitudes as a function of time, or the inverse Fourier transformation (IFT) calculates the time domain from the frequency domain. The FT is used to generate the spectrum from the free induction decay or spin echo in the pulse MR technique and is essential to most MR imaging techniques. The Fourier transformation can be generalized to multiple dimensions, e.g. to relate an image to its corresponding k-space representation, or to include chemical shift information in some chemical shift imaging techniques. Fourier transformation analysis allows spatial information to be reconstructed from the raw data.
Nuclei can retain their magnetic orientation through a chemical reaction. Thus, if RF radiation is supplied to the spins at a frequency corresponding to the chemical shift of the nuclei in one chemical state so as to produce saturation or inversion, and chemical reactions transform the nuclei into another chemical state with a different chemical shift in a time short compared to the relaxation time, the NMRspectrum may show the effects of the saturation or inversion on the corresponding, unirradiated line in the spectrum. This technique can be used to study reaction kinetics of suitable molecules.
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