title: An iterative reconstruction technique for geometric distortion-corrected segmented echo-planar imaging.
abstract: In this article, we present a modified interleaved segmented echo-planar imaging (SEPI) sequence with a center-out k-space trajectory that is especially designed for susceptibility-weighted imaging applications. We introduce a simple and efficient technique to phase correct the acquired SEPI data in the presence of moderate field inhomogeneities. This phase correction reduces the distortion in the phase-encoding direction without requiring an extra reference scan. With the use of a center-out k-space trajectory and a low-spatial-frequency phase map, phase discontinuities between segments can be eliminated, in principle, iteratively using a fast Fourier transform from the center segment to the outermost segment in k-space. With an extra echo added in front of the echo train, neither phase unwrapping nor an extra reference scan is required to obtain a low-spatial-frequency phase map. The method is shown to remove blurring and reduce geometric distortion caused by phase changes from echo to echo in both phantom and human data. The method is most useful for high-resolution imaging applications and moderate factors of speed improvement.
authors.affiliation: Department of Electric and Computer Engineering, McMaster University, Hamilton, Ontario, Canada. am4229@wayne.edu
authors.forename: Yingbiao
authors.initials: Y
authors.lastname: Xu
authors.forename: E Mark
authors.initials: EM
authors.lastname: Haacke
mesh_terms: D016477:Artifacts; D001931:Brain Mapping / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging
references.citation: IEEE Trans Med Imaging. 1999 Jun;18(6):481-95
references.pmid: 10463127
references.citation: Magn Reson Med. 1999 Nov;42(5):963-9
references.pmid: 10542356
references.citation: Magn Reson Med. 1997 Jun;37(6):932-42
references.pmid: 9178246
references.citation: Magn Reson Med. 1995 Jul;34(1):65-73
references.pmid: 7674900
references.citation: IEEE Trans Med Imaging. 1991;10(4):629-37
references.pmid: 18222870
references.citation: Magn Reson Med. 1994 Oct;32(4):535-9
references.pmid: 7997122
references.citation: Magn Reson Med. 1997 Mar;37(3):436-47
references.pmid: 9055235
references.citation: Radiology. 1986 Feb;158(2):521-9
references.pmid: 3941881
references.citation: Magn Reson Med. 2004 Sep;52(3):612-8
references.pmid: 15334582
references.citation: Magn Reson Med. 2001 Apr;45(4):623-9
references.pmid: 11283990
references.citation: Magn Reson Med. 2001 Mar;45(3):525-8
references.pmid: 11241714
references.citation: IEEE Trans Med Imaging. 1996;15(6):893-7
references.pmid: 18215968
references.citation: Magn Reson Med. 1999 Jun;41(6):1206-13
references.pmid: 10371453
references.citation: Magn Reson Med. 1998 Feb;39(2):328-30
references.pmid: 9469719