Multiparametric and longitudinal MRI characterization of mild traumatic brain injury in rats

J Neurotrauma. 2015 Apr 15;32(8):598-607. doi: 10.1089/neu.2014.3563. Epub 2015 Jan 22.


This study reports T2 and diffusion-tensor magnetic resonance imaging (MRI) studies of a mild open-skull, controlled cortical impact injury in rats (n=6) from 3 h to up to 14 d after traumatic brain injury (TBI). Comparison was made with longitudinal behavioral measurements and end-point histology. The impact was applied over the left primary forelimb somatosensory cortex (S1FL). The major findings were: 1) In the S1FL, T2 increased and fractional anisotropy (FA) decreased at 3 h after TBI and gradually returned toward normal by Day 14; 2) in the S1FL, the apparent diffusion coefficient (ADC) increased at 3 h, peaked on Day 2, and gradually returned toward normal at Day 14; 3) in the corpus callosum underneath the S1FL, FA decreased at 3 h to Day 2 but returned to normal at Day 7 and 14, whereas T2 and ADC were normal throughout; 4) heterogeneous hyperintense and hypointense T2 map intensities likely indicated the presence of hemorrhage but were not independently verified; 5) lesion volumes defined by abnormal T2, ADC, and FA showed similar temporal patterns, peaking around Day 2 and returning toward normal on Day 14; 6) the temporal profiles of lesion volumes were consistent with behavioral scores assessed by forelimb placement and forelimb foot fault tests; and 7) at 14 d post-TBI, there was substantial tissue recovery by MRI, which could either reflect true tissue recovery or reabsorption of edema. Histology performed 14 d post-TBI, however, showed a small cavitation and significant neuronal degeneration surrounding the cavitation in S1FL. Thus, the observed improvement of behavioral scores likely involves both functional recovery and functional compensation.

Keywords: TBI; behavioral assessments; controlled cortical impact; diffusion tensor imaging; immunohistochemistry; quantitative magnetic resonance imaging.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Behavior, Animal
  • Brain Injuries / pathology*
  • Brain Injuries / physiopathology
  • Longitudinal Studies
  • Magnetic Resonance Imaging / methods*
  • Male
  • Rats
  • Rats, Sprague-Dawley
  • Recovery of Function