title: Quantifying the impact of underlying measurement error on cervical spinal cord diffusion tensor imaging at 3T.
abstract: To empirically characterize and quantify the impact of gradient weighting schemes on the appearance and fidelity of diffusion tensor imaging of the human spinal cord in vivo in clinically relevant scan time equivalents (STE).
  
  
  
  In five healthy controls at 3T, we evaluated test-retest reproducibility and performed voxelwise analysis of diffusion tensor imaging (DTI)-derived indices (fractional anisotropy [FA], mean [MD], axial [AD], and radial [RD] diffusivity) in the cervical spinal cord to assess spatial dependencies of measurement error and differences across three different sampling schemes (6, 15, and 32 directions) at STE of 4.5, 9, and 18 minutes. A subjective assessment was also performed.
  
  
  
  With six directions, column-specific errors are highest (effect size = 2.9%, 4.4%, 7.2% for FA in dorsal column, lateral column, and gray matter) and different than the 15-direction scheme (P < 0.05). STE sequences with 15 and 32 directions exhibited small differences in error (P > 0.05). For FA and AD, measurement errors are prevalent in gray matter, while partial volume effects with cerebrospinal fluid heavily influence RD. Measurement errors decreased with increasing scan time (P < 0.01), albeit with diminishing returns at scan times longer than 9 minutes (P < 0.05).
  
  
  
  A 15-direction scheme of 9 minutes yields measurements of the cervical spinal cord with low error. J. Magn. Reson. Imaging 2016;44:1608-1618.
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.|Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Samantha
authors.initials: S
authors.lastname: By
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.|Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Alex K
authors.initials: AK
authors.lastname: Smith
authors.affiliation: Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.|Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Lindsey M
authors.identifier: 0000-0002-2070-6663
authors.initials: LM
authors.lastname: Dethrage
authors.affiliation: Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Bailey D
authors.initials: BD
authors.lastname: Lyttle
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.|Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.|Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.|Department of Electrical Engineering, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Bennett A
authors.initials: BA
authors.lastname: Landman
authors.affiliation: Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Creasy
authors.affiliation: Department of Neurology, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Siddharama
authors.initials: S
authors.lastname: Pawate
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.|Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.|Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Seth A
authors.initials: SA
authors.lastname: Smith
mesh_terms: D000328:Adult; D000465:Algorithms; D016880:Anisotropy; D002555:Cerebrospinal Fluid / Q000000981:diagnostic imaging*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013116:Spinal Cord / Q000000981:diagnostic imaging*
keywords: diffusion tensor imaging; magnetic resonance imaging; spinal cord