title: Radial diffusivity in remote optic neuritis discriminates visual outcomes.
abstract: OBJECTIVE
  Diffusion tensor imaging (DTI) quantifies Brownian motion of water within tissue. The goal of this study was to test whether, following a remote episode of optic neuritis (ON), breakdown of myelin and axons within the optic nerve could be detected by alterations in DTI parameters, and whether these alterations would correlate with visual loss.
  
  
  METHODS
  Seventy subjects with a history of ON > or =6 months prior underwent DTI of the optic nerves, assessment of visual acuities (VA) and contrast sensitivities (CS), and laboratory measures of visual evoked potentials (VEP) and optical coherence tomography (OCT).
  
  
  RESULTS
  Radial diffusivity (RD) correlated with visual acuity (r = -0.61), Pelli-Robson CS (r = -0.60), 5%CS (r = 0.61), OCT (r = -0.78), VEP latency (r = 0.61), and VEP amplitude (r = -0.46). RD differentiated the unaffected fellow nerves from affected nerves in all visual outcome categories. RD also discriminated nerves with recovery to normal from mild visual impairment, and those with mild impairment from profound visual loss. RD differentiated healthy controls from both clinically affected nerves and unaffected fellow nerves after ON. RD differentiated all categories of 5%CS outcomes, and all categories of Pelli-Robson CS with the exception of normal recovery from mildly affected.
  
  
  CONCLUSIONS
  Increased optic nerve radial diffusivity (RD) detected by diffusion tensor imaging (DTI) was associated with a proportional decline in vision after optic neuritis. RD can differentiate healthy control nerves from both affected and unaffected fellow nerves. RD can discriminate among categories of visual recovery within affected eyes. Optic nerve injury as assessed by DTI was corroborated by both optical coherence tomography and visual evoked potentials.
authors.affiliation: Neurology, Washington University, St. Louis, MO 63110, USA. naismithr@neuro.wustl.edu
authors.forename: R T
authors.initials: RT
authors.lastname: Naismith
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: N T
authors.initials: NT
authors.lastname: Tutlam
authors.forename: K
authors.initials: K
authors.lastname: Trinkaus
authors.forename: A H
authors.initials: AH
authors.lastname: Cross
authors.forename: S-K
authors.initials: SK
authors.lastname: Song
mesh_terms: D000328:Adult; D000368:Aged; D016880:Anisotropy; D016001:Confidence Intervals; D015350:Contrast Sensitivity / Q000502:physiology*; D056324:Diffusion Tensor Imaging / Q000379:methods; D004192:Discrimination, Psychological / Q000502:physiology; D005074:Evoked Potentials, Visual / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009900:Optic Nerve / Q000473:pathology; D009902:Optic Neuritis / Q000150:complications* / Q000175:diagnosis*; D010775:Photic Stimulation / Q000379:methods; D013223:Statistics as Topic; D041623:Tomography, Optical Coherence / Q000379:methods; D014786:Vision Disorders / Q000209:etiology*; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult