title: A longitudinal MRI study of traumatic axonal injury in patients with moderate and severe traumatic brain injury.
abstract: OBJECTIVE
  To study the evolution of traumatic axonal injury (TAI) detected by structural MRI in patients with moderate and severe traumatic brain injury (TBI) during the first year and relate findings to outcome.
  
  
  METHODS
  58 patients with TBI (Glasgow Coma Scale score 3-13) were examined with MRI at a median of 7 days, 3 months and 12 months post injury. TAI lesions were evaluated blinded and categorised into three stages based on location: hemispheres, corpus callosum and brainstem. Lesions in T2* weighted gradient echo (GRE), fluid attenuated inversion recovery (FLAIR) and diffusion weighted imaging (DWI) were counted and FLAIR lesion volumes were estimated. Inter-rater reliability score was calculated. Outcome was assessed 12 months post injury using the Glasgow Outcome Scale Extended.
  
  
  RESULTS
  In the initial MRI, 31% had brainstem lesions compared with 17% at 3 months (p=0.008). In the FLAIR sequences, number and volumes of lesions were reduced from early to 3 months (p<0.001). In T2*GRE sequences, the number of lesions persisted at 3 months but was reduced at 12 months (p=0.007). The number of lesions in DWI and volume of FLAIR lesions on early MRI predicted worse clinical outcome in adjusted analyses (p<0.05).
  
  
  CONCLUSIONS
  This is the first study to demonstrate and quantify attenuation of non-haemorrhagic TAI lesions on structural MRI during the first 3 months after TBI; most importantly, the disappearance of brainstem lesions. Haemorrhagic TAI lesions attenuate first after 3 months. Only early MRI findings predicted clinical outcome after adjustment for other prognostic factors. Hence valuable clinical information may be missed if MRI is performed too late after TBI.
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology (NTNU), Trondheim N-7489, Norway. kent.g.moen@ntnu.no
authors.forename: Kent Gøran
authors.initials: KG
authors.lastname: Moen
authors.forename: Toril
authors.initials: T
authors.lastname: Skandsen
authors.forename: Mari
authors.initials: M
authors.lastname: Folvik
authors.forename: Veronika
authors.initials: V
authors.lastname: Brezova
authors.forename: Kjell Arne
authors.initials: KA
authors.lastname: Kvistad
authors.forename: Jana
authors.initials: J
authors.lastname: Rydland
authors.forename: Geoffrey T
authors.initials: GT
authors.lastname: Manley
authors.forename: Anne
authors.initials: A
authors.lastname: Vik
mesh_terms: D000293:Adolescent; D000328:Adult; D001369:Axons / Q000473:pathology*; D001921:Brain / Q000473:pathology*; D001930:Brain Injuries / Q000473:pathology*; D002648:Child; D003627:Data Interpretation, Statistical; D020833:Diffuse Axonal Injury / Q000473:pathology*; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D016896:Treatment Outcome; D055815:Young Adult