title: Simulated phase evolution rewinding (SPHERE): a technique for reducing B0 inhomogeneity effects in MR images.
abstract: A novel method for reducing field inhomogeneity effects in magnetic resonance images is described in this paper. Observing that image degradation arises from B0 inhomogeneity-induced phase accrual during data acquisition, the present method numerically rewinds the accumulated phase in the k-space data based on an initial estimate of the image and a corresponding field map. The rewinding process generates a corrected k-space data set that is subsequently Fourier transformed to produce the final image. In this paper, a theoretical analysis of the method and applications of the technique to magnetic resonance imaging data are presented. The theoretical analysis of the method indicates that it is a general approach applicable to a variety of sequences. Results obtained by applying the method to experimental data acquired with single-shot echo-planar imaging, segmented echo-planar imaging with centric reordering, and spiral sequences demonstrate that it is robust in reducing image degradation induced by B0 inhomogeneity.
authors.affiliation: Department of Radiology, and Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis 55455, USA.
authors.forename: Y M
authors.initials: YM
authors.lastname: Kadah
authors.forename: X
authors.initials: X
authors.lastname: Hu
mesh_terms: D001921:Brain / Q000033:anatomy & histology; D003198:Computer Simulation; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted