Removal of chemical-shift effects in NMR imaging.
A simple and fast method is introduced which eliminates the effects of a distribution of chem. shifts in NMR imaging. When the gradient induced shift is not much larger than the distribution of chem. shifts, distortions are obsd. which smear the image and degrade the resoln. To restore the image, it is deconvoluted by the NMR spectrum of the sample. Provided that all of the resonances have the same spatial distribution, this procedure results in a correct image with a significantly higher signal-to-noise. The demands of spectral processing are minimized by performing the deconvolution in the time domain where it corresponds to division. The applications of this technique to back-projection (BP) reconstruction and 2-dimensional Fourier imaging methods are discussed, and examples are shown of a BP image of polybutadiene. The polybutadiene image was acquired with magic-angle sample spinning to av. chem.-shift anisotropies.
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