Microstructural Tissue Changes in a Rat Model of Mild Traumatic Brain Injury

Frontiers in Neuroscience

Omar Narvaez¹  Karthik Chary¹  Raimo A. Salo¹  Alejandra Sierra¹  Olli Gröhn¹  Isabel San Martín Molina¹  Jussi Tohka¹  Manisha Aggarwal² 

[1] A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland;Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States;

关键词: traumatic brain injury;    fixel-based analysis;    diffusion tensor imaging;    axonal damage;    gliosis;    histology;   

DOI  :  10.3389/fnins.2021.746214

来源: DOAJ

【 摘 要 】

Our study investigates the potential of diffusion MRI (dMRI), including diffusion tensor imaging (DTI), fixel-based analysis (FBA) and neurite orientation dispersion and density imaging (NODDI), to detect microstructural tissue abnormalities in rats after mild traumatic brain injury (mTBI). The brains of sham-operated and mTBI rats 35 days after lateral fluid percussion injury were imaged ex vivo in a 11.7-T scanner. Voxel-based analyses of DTI-, fixel- and NODDI-based metrics detected extensive tissue changes in directly affected brain areas close to the primary injury, and more importantly, also in distal areas connected to primary injury and indirectly affected by the secondary injury mechanisms. Histology revealed ongoing axonal abnormalities and inflammation, 35 days after the injury, in the brain areas highlighted in the group analyses. Fractional anisotropy (FA), fiber density (FD) and fiber density and fiber bundle cross-section (FDC) showed similar pattern of significant areas throughout the brain; however, FA showed more significant voxels in gray matter areas, while FD and FDC in white matter areas, and orientation dispersion index (ODI) in areas most damage based on histology. Region-of-interest (ROI)-based analyses on dMRI maps and histology in selected brain regions revealed that the changes in MRI parameters could be attributed to both alterations in myelinated fiber bundles and increased cellularity. This study demonstrates that the combination of dMRI methods can provide a more complete insight into the microstructural alterations in white and gray matter after mTBI, which may aid diagnosis and prognosis following a mild brain injury.

【 授权许可】

Unknown