Field inhomogeneity correction and data processing for spectroscopic imaging

To obtain separate NMR images of spatially resolved high-resolution chemical-shift information the effects of magnetic field inhomogeneity must be accounted for. A suitable correction method is described which relies on first generating a plot of the magnetic field distribution. Using these data the spectroscopic imaging data can be processed to display the spatial distributions of separate resonances without distortion from field inhomogeneity. The field plot is obtained by using the same data acquisition sequence while imaging a phantom object or in particular cases the plot may be derived from the spectroscopic imaging data set itself. The correction procedure is illustrated using proton in vivo imaging of a cat. Some additional data processing techniques are presented which offer alternative methods of displaying spectroscopic imaging data.