title: Spinal cord tract diffusion tensor imaging reveals disability substrate in demyelinating disease.
abstract: OBJECTIVE
  This study assessed the tissue integrity of major cervical cord tracts by using diffusion tensor imaging (DTI) to determine the relationship with specific clinical functions carried by those tracts.
  
  
  METHODS
  This was a cross-sectional study of 37 patients with multiple sclerosis or neuromyelitis optica with remote cervical cord disease. Finger vibratory thresholds, 25-foot timed walk (25FTW), 9-hole peg test (9HPT), and Expanded Disability Status Scale were determined. DTI covered cervical regions C1 through C6 with 17 5-mm slices (0.9 × 0.9 mm in-plane resolution). Regions of interest included posterior columns (PCs) and lateral corticospinal tracts (CSTs). Hierarchical linear mixed-effect modeling included covariates of disease subtype (multiple sclerosis vs neuromyelitis optica), disease duration, and sex.
  
  
  RESULTS
  Vibration thresholds were associated with radial diffusivity (RD) and fractional anisotropy (FA) in the PCs (both p < 0.01), but not CSTs (RD, p = 0.29; FA, p = 0.14). RD and FA in PCs, and RD in CSTs were related to 9HPT (each p < 0.0001). 25FTW was associated with RD and FA in PCs (p < 0.0001) and RD in CSTs (p = 0.008). Expanded Disability Status Scale was related to RD and FA in PCs and CSTs (p < 0.0001). Moderate/severe impairments in 9HPT (p = 0.006) and 25FTW (p = 0.017) were more likely to show combined moderate/severe tissue injury within both PCs and CSTs by DTI.
  
  
  CONCLUSIONS
  DTI can serve as an imaging biomarker of spinal cord tissue injury at the tract level. RD and FA demonstrate strong and consistent relationships with clinical outcomes, specific to the clinical modality.
authors.affiliation: Department of Neurology, Washington University, St. Louis, MO, USA. naismithr@neuro.wustl.edu
authors.forename: Robert T
authors.initials: RT
authors.lastname: Naismith
authors.forename: Junqian
authors.initials: J
authors.lastname: Xu
authors.forename: Eric C
authors.initials: EC
authors.lastname: Klawiter
authors.forename: Samantha
authors.initials: S
authors.lastname: Lancia
authors.forename: Nhial T
authors.initials: NT
authors.lastname: Tutlam
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Wagner
authors.forename: Peiqing
authors.initials: P
authors.lastname: Qian
authors.forename: Kathryn
authors.initials: K
authors.lastname: Trinkaus
authors.forename: Sheng-Kwei
authors.initials: SK
authors.lastname: Song
authors.forename: Anne H
authors.initials: AH
authors.lastname: Cross
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D056324:Diffusion Tensor Imaging / Q000379:methods*; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology*; D009471:Neuromyelitis Optica / Q000473:pathology*; D013116:Spinal Cord / Q000473:pathology*