title: Evaluation of preprocessing steps to compensate for magnetic field distortions due to body movements in BOLD fMRI.
abstract: Blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is currently the dominant technique for non-invasive investigation of brain functions. One of the challenges with BOLD fMRI, particularly at high fields, is compensation for the effects of spatiotemporally varying magnetic field inhomogeneities (DeltaB(0)) caused by normal subject respiration and, in some studies, movement of the subject during the scan to perform tasks related to the functional paradigm. The presence of DeltaB(0) during data acquisition distorts reconstructed images and introduces extraneous fluctuations in the fMRI time series that decrease the BOLD contrast-to-noise ratio. Optimization of the fMRI data-processing pipeline to compensate for geometric distortions is of paramount importance to ensure high quality of fMRI data. To investigate DeltaB(0) caused by subject movement, echo-planar imaging scans were collected with and without concurrent motion of a phantom arm. The phantom arm was constructed and moved by the experimenter to emulate forearm motions while subjects remained still and observed a visual stimulation paradigm. These data were then subjected to eight different combinations of preprocessing steps. The best preprocessing pipeline included navigator correction, a complex phase regressor and spatial smoothing. The synergy between navigator correction and phase regression reduced geometric distortions better than either step in isolation and preconditioned the data to make them more amenable to the benefits of spatial smoothing. The combination of these steps provided a 10% increase in t-statistics compared to only navigator correction and spatial smoothing and reduced the noise and false activations in regions where no legitimate effects would occur.
authors.affiliation: Centre for Functional and Metabolic Mapping, Robarts Research Institute, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Barry
authors.forename: Joy M
authors.initials: JM
authors.lastname: Williams
authors.forename: L Martyn
authors.initials: LM
authors.lastname: Klassen
authors.forename: Jason P
authors.initials: JP
authors.lastname: Gallivan
authors.forename: Jody C
authors.initials: JC
authors.lastname: Culham
authors.forename: Ravi S
authors.initials: RS
authors.lastname: Menon
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001931:Brain Mapping / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009068:Movement; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
references.citation: Magn Reson Med. 2004 Jan;51(1):16-21
references.pmid: 14705040
references.citation: Magn Reson Med. 2005 Aug;54(2):411-8
references.pmid: 16032665
references.citation: J Neurophysiol. 2004 Oct;92(4):2428-43
references.pmid: 15163677
references.citation: Magn Reson Med. 1995 Aug;34(2):201-12
references.pmid: 7476079
references.citation: Magn Reson Med. 1995 Jul;34(1):65-73
references.pmid: 7674900
references.citation: Magn Reson Med. 1992 Feb;23(2):311-23
references.pmid: 1549045
references.citation: Neuroimage. 2005 Sep;27(3):624-34
references.pmid: 15975828
references.citation: Exp Brain Res. 2003 Nov;153(2):180-9
references.pmid: 12961051
references.citation: Neuroimage. 2008 Feb 1;39(3):1142-50
references.pmid: 18024159
references.citation: IEEE Eng Med Biol Mag. 2006 Mar-Apr;25(2):27-41
references.pmid: 16568935
references.citation: Magn Reson Med. 2001 Jul;46(1):198-201
references.pmid: 11443728
references.citation: PLoS One. 2007 May 09;2(5):e424
references.pmid: 17487272
references.citation: Neuroimage. 2003 Jan;18(1):10-27
references.pmid: 12507440
references.citation: Magn Reson Med. 1996 Mar;35(3):346-55
references.pmid: 8699946
references.citation: Hum Brain Mapp. 1999;7(2):106-14
references.pmid: 9950068
references.citation: Proc Natl Acad Sci U S A. 1992 Jul 1;89(13):5951-5
references.pmid: 1631079
references.citation: Magn Reson Med. 2001 Aug;46(2):344-53
references.pmid: 11477639
references.citation: AJNR Am J Neuroradiol. 2000 Sep;21(8):1388-96
references.pmid: 11003269
references.citation: Magn Reson Med. 1997 Dec;38(6):1029-34
references.pmid: 9402206
references.citation: Magn Reson Med. 2004 May;51(5):881-7
references.pmid: 15122668
references.citation: Proc Natl Acad Sci U S A. 1992 Jun 15;89(12):5675-9
references.pmid: 1608978
references.citation: Neuroimage. 2004;23 Suppl 1:S196-207
references.pmid: 15501090
references.citation: Neuroimage. 2007 Aug 1;37(1):177-88
references.pmid: 17560130
references.citation: AJNR Am J Neuroradiol. 1996 Jun-Jul;17(6):1005-9
references.pmid: 8791907
references.citation: Neuroimage. 2001 May;13(5):903-19
references.pmid: 11304086
references.citation: Magn Reson Med. 2000 Jul;44(1):162-7
references.pmid: 10893535
references.citation: Neuroimage. 2005 Apr 15;25(3):802-14
references.pmid: 15808981
references.citation: Magn Reson Med. 1998 Jul;40(1):55-60
references.pmid: 9660553
references.citation: Magn Reson Med. 2002 Feb;47(2):344-53
references.pmid: 11810679
references.citation: Comput Biomed Res. 1996 Jun;29(3):162-73
references.pmid: 8812068
references.citation: Neuroreport. 1994 Mar 21;5(7):813-6
references.pmid: 8018855
references.citation: Magn Reson Med. 1992 Jun;25(2):390-7
references.pmid: 1614324
references.citation: Magn Reson Med. 1994 Mar;31(3):283-91
references.pmid: 8057799
references.citation: Neuroimage. 2001 Sep;14(3):709-22
references.pmid: 11506543
references.citation: Neuroimage. 2005 Nov 15;28(3):529-43
references.pmid: 16099178
references.citation: Magn Reson Med. 2002 Jan;47(1):1-9
references.pmid: 11754436
references.citation: Magn Reson Med. 1994 May;31(5):495-503
references.pmid: 8015402
references.citation: Magn Reson Med. 1996 Mar;35(3):290-8
references.pmid: 8699939