title: The importance of correcting for signal drift in diffusion MRI.
abstract: To investigate previously unreported effects of signal drift as a result of temporal scanner instability on diffusion MRI data analysis and to propose a method to correct this signal drift.
  
  
  
  We investigated the signal magnitude of non-diffusion-weighted EPI volumes in a series of diffusion-weighted imaging experiments to determine whether signal magnitude changes over time. Different scan protocols and scanners from multiple vendors were used to verify this on phantom data, and the effects on diffusion kurtosis tensor estimation in phantom and in vivo data were quantified. Scalar metrics (eigenvalues, fractional anisotropy, mean diffusivity, mean kurtosis) and directional information (first eigenvectors and tractography) were investigated.
  
  
  
  Signal drift, a global signal decrease with subsequently acquired images in the scan, was observed in phantom data on all three scanners, with varying magnitudes up to 5% in a 15-min scan. The signal drift has a noticeable effect on the estimation of diffusion parameters. All investigated quantitative parameters as well as tractography were affected by this artifactual signal decrease during the scan.
  
  
  
  By interspersing the non-diffusion-weighted images throughout the session, the signal decrease can be estimated and compensated for before data analysis; minimizing the detrimental effects on subsequent MRI analyses. Magn Reson Med 77:285-299, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.
authors.affiliation: Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands.|Translational Imaging Group, Centre for Medical Image Computing, University College London, London, UK.
authors.forename: Sjoerd B
authors.initials: SB
authors.lastname: Vos
authors.affiliation: Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands.
authors.forename: Chantal M W
authors.initials: CM
authors.lastname: Tax
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Luijten
authors.affiliation: Translational Imaging Group, Centre for Medical Image Computing, University College London, London, UK.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Ourselin
authors.affiliation: Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands.
authors.forename: Alexander
authors.initials: A
authors.lastname: Leemans
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands.
authors.forename: Martijn
authors.initials: M
authors.lastname: Froeling
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009412:Nerve Fibers / Q000502:physiology; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted
keywords: artefact correction; diffusion tensor imaging; fiber tractography; high angular resolution diffusion imaging