Structural and metabolic changes in the traumatically injured rat brain: high-resolution in vivo proton magnetic resonance spectroscopy at 7 T

The understanding of microstructural and metabolic changes in the post-traumatic brain injury is the key to brain damage suppression and repair in clinics. Ten female Wistar rats were traumatically injured in the brain CA1 region and above the cortex. Next, diffusion tensor magnetic resonance imaging (DTI) and proton magnetic resonance spectroscopy (H-1 MRS) were used to analyze the microstructural and metabolic changes in the brain within the following 2 weeks. Anisotropy fraction (FA) and axial diffusivity (AD) of the corpus callosum (CC) began to decrease significantly at day 1, whereas radial diffusivity (RD) significantly increased immediately after injury, reflecting the loss of white matter integrity. Compared with day 3, RD decreased significantly at day 7, implicating the angioedema reduction. In the hippocampus, FA significantly increased at day 7; the choline-containing compounds (Cho) and myo-inositol (MI) remarkably increased at day 7 compared with those at day 3, indicating the proliferation of astrocytes and radial glial cells after day 7. No significant differences between DTI and H-1 MRS parameters were observed between day 1 and day 3. Day 1-3 after traumatic brain injury (TBI) may serve as a relatively appropriate time window for treatment planning and the following nerve repair.