title: Diffuse axonal injury associated with chronic traumatic brain injury: evidence from T2*-weighted gradient-echo imaging at 3 T.
abstract: OBJECTIVE
  Diffuse axonal injury is frequently accompanied by tissue tear hemorrhages. We examined whether high field strength T2*-weighted gradient-echo imaging performed during the chronic stage of traumatic brain injury may have advantages in the evaluation of diffuse axonal injury as compared with T1- and T2-weighted MR imaging.
  
  
  METHODS
  Prospective MR imaging of 66 patients (age range, 17-57 years) was performed using a 3-T system 3 to 292 months (median, 23.5 months) after traumatic brain injury. T1-, T2-, T2*-hypointense and T2-hyperintense foci of 1- to 15-mm diameter were registered in 10 brain regions by two readers separately. Foci that appeared hypointense both on the T1- and T2- and/or on the T2*-weighted images were defined as traumatic microbleeds.
  
  
  RESULTS
  For 46 (69.7%) of the patients, T2*-weighted gradient-echo imaging revealed traumatic microbleeds. Hyperintense foci were observed on the T2-weighted images of only 15 (22.7%) patients. T2*-weighted imaging showed significantly more traumatic microbleeds (P =.000) than did T1- and T2-weighted imaging. Interobserver agreement was strong (kappa = 0.79, tau = 0.749, P =.000). For 14 (21.2%) of the patients, T2*-weighted gradient-echo imaging revealed traumatic microbleeds in the corpus callosum, whereas for only two (3%), hyperintense callosal lesions were seen on the T2-weighted images. Although a significant correlation existed between the total amount and callosal appearance of traumatic microbleeds and Glasgow Coma Scale scores (P =.000), no correlation existed with extended Glasgow Outcome Scale scores.
  
  
  CONCLUSIONS
  T2*-weighted gradient-echo imaging at high field strength is a useful tool for the evaluation of diffuse axonal injury during the chronic stage of traumatic brain injury. Diffuse axonal injury-related brain lesions are mainly hemorrhagic. The relevance of diffuse axonal injury for long-term clinical outcome is uncertain.
authors.affiliation: Day Clinic of Cognitive Neurology, University of Leipzig, Liebigstrasse 22a, 04103 Leipzig, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Scheid
authors.forename: Cristoph
authors.initials: C
authors.lastname: Preul
authors.forename: Oliver
authors.initials: O
authors.lastname: Gruber
authors.forename: Christopher
authors.initials: C
authors.lastname: Wiggins
authors.forename: D Yves
authors.initials: DY
authors.lastname: von Cramon
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000473:pathology; D020208:Brain Injury, Chronic / Q000175:diagnosis*; D020202:Cerebral Hemorrhage, Traumatic / Q000175:diagnosis; D003337:Corpus Callosum / Q000473:pathology; D020833:Diffuse Axonal Injury / Q000175:diagnosis*; D017352:Echo-Planar Imaging; D005260:Female; D015600:Glasgow Coma Scale; D023261:Glasgow Outcome Scale; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies