title: Increased radial diffusivity in spinal cord lesions in neuromyelitis optica compared with multiple sclerosis.
abstract: BACKGROUND
  Multiple sclerosis (MS) and neuromyelitis optica (NMO) both affect spinal cord with notable differences in pathology.
  
  
  OBJECTIVE
  Determine the utility of diffusion tensor imaging (DTI) to differentiate the spinal cord lesions of NMO from MS within and outside T2 lesions.
  
  
  METHODS
  Subjects greater than or equal to 12 months from a clinical episode of transverse myelitis underwent a novel transaxial cervical spinal cord DTI sequence. Ten subjects with NMO, 10 with MS and 10 healthy controls were included.
  
  
  RESULTS
  Within T2 affected white matter regions, radial diffusivity was increased in both NMO and MS compared with healthy controls (p<0.001, respectively), and to a greater extent in NMO than MS (p<0.001). Axial diffusivity was decreased in T2 lesions in both NMO and MS compared with controls (p<0.001, p=0.001), but did not differ between the two diseases. Radial diffusivity and fractional anisotropy within white matter regions upstream and downstream of T2 lesions were different from controls in each disease.
  
  
  CONCLUSIONS
  Higher radial diffusivity within spinal cord white matter tracts derived from diffusion tensor imaging were appreciated in NMO compared with MS, consistent with the known greater tissue destruction seen in NMO. DTI also detected tissue alterations outside T2 lesions and may be a surrogate of anterograde and retrograde degeneration.
authors.affiliation: Department of Neurology, Washington University School of Medicine, St Louis, USA. eklawiter@partners.org
authors.forename: Eric C
authors.initials: EC
authors.lastname: Klawiter
authors.forename: Junqian
authors.initials: J
authors.lastname: Xu
authors.forename: Robert T
authors.initials: RT
authors.lastname: Naismith
authors.forename: Tammie L S
authors.initials: TL
authors.lastname: Benzinger
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Shimony
authors.forename: Samantha
authors.initials: S
authors.lastname: Lancia
authors.forename: Abraham Z
authors.initials: AZ
authors.lastname: Snyder
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; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology*; D009410:Nerve Degeneration; D009471:Neuromyelitis Optica / Q000473:pathology*; D011237:Predictive Value of Tests; D013116:Spinal Cord / Q000473:pathology*; D055815:Young Adult