NMR imaging in the presence of magnetic field inhomogeneities and gradient field nonlinearities

The relative merits of the spin-warp method and the multiple-angle projection-reconstruction method are assessed for nuclear magnetic resonance imaging in the presence of magnetic field inhomogeneities. The results of computer modeling studies demonstrate the superiority of the spin-warp method under these conditions. Because the form of the point spread function for the spin-warp approach is insensitive to magnetic field irregularities, simple correction algorithms have been developed to reduce artifacts associated with bias field inhomogeneities. In addition, the formalism developed for magnetic field inhomogeneities can be easily extended to correct for gradient field nonlinearities.