title: Mapping traumatic axonal injury using diffusion tensor imaging: correlations with functional outcome.
abstract: BACKGROUND
  Traumatic brain injury is a major cause of morbidity and mortality worldwide. Ameliorating the neurocognitive and physical deficits that accompany traumatic brain injury would be of substantial benefit, but the mechanisms that underlie them are poorly characterized. This study aimed to use diffusion tensor imaging to relate clinical outcome to the burden of white matter injury.
  
  
  RESULTS
  Sixty-eight patients, categorized by the Glasgow Outcome Score, underwent magnetic resonance imaging at a median of 11.8 months (range 6.6 months to 3.7 years) years post injury. Control data were obtained from 36 age-matched healthy volunteers. Mean fractional anisotropy, apparent diffusion coefficient (ADC), and eigenvalues were obtained for regions of interest commonly affected in traumatic brain injury. In a subset of patients where conventional magnetic resonance imaging was completely normal, diffusion tensor imaging was able to detect clear abnormalities. Significant trends of increasing ADC with worse outcome were noted in all regions of interest. In the white matter regions of interest worse clinical outcome corresponded with significant trends of decreasing fractional anisotropy.
  
  
  CONCLUSIONS
  This study found that clinical outcome was related to the burden of white matter injury, quantified by diffusivity parameters late after traumatic brain injury. These differences were seen even in patients with the best outcomes and patients in whom conventional magnetic resonance imaging was normal, suggesting that diffusion tensor imaging can detect subtle injury missed by other techniques. An improved in vivo understanding of the pathology of traumatic brain injury, including its distribution and extent, may enhance outcome evaluation and help to provide a mechanistic basis for deficits that remain unexplained by other approaches.
authors.affiliation: University Division of Anaesthesia, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Virginia
authors.initials: V
authors.lastname: Newcombe
authors.forename: Doris
authors.initials: D
authors.lastname: Chatfield
authors.forename: Joanne
authors.initials: J
authors.lastname: Outtrim
authors.forename: Sarah
authors.initials: S
authors.lastname: Vowler
authors.forename: Anne
authors.initials: A
authors.lastname: Manktelow
authors.forename: Justin
authors.initials: J
authors.lastname: Cross
authors.forename: Daniel
authors.initials: D
authors.lastname: Scoffings
authors.forename: Martin
authors.initials: M
authors.lastname: Coleman
authors.forename: Peter
authors.initials: P
authors.lastname: Hutchinson
authors.forename: Jonathan
authors.initials: J
authors.lastname: Coles
authors.forename: T Adrian
authors.initials: TA
authors.lastname: Carpenter
authors.forename: John
authors.initials: J
authors.lastname: Pickard
authors.forename: Guy
authors.initials: G
authors.lastname: Williams
authors.forename: David
authors.initials: D
authors.lastname: Menon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001930:Brain Injuries / Q000473:pathology*; D016022:Case-Control Studies; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult