Yu-Han Hong1, Yi-Wen Peng2, Yeu-Sheng Tyan1, 3, Jun-Cheng Weng1, 3
1School of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan; 2Department of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan; 3Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung, Taiwan
Characterizing complex anatomy at different stages of brain development not only aids in understanding this highly ordered process but also provides clues to detecting abnormalities caused by genetic or environmental factors. Diffusion tensor tractography allows for the in vivo delineation of white matter tracts in the brain in a manner that is individualized to the particular neuroanatomy of each subject. Diffusion anisotropy and diffusivity change in some brain regions with demyelinating disease and also with neural development. However few studies identify these changes along the white matter tracts. Therefore the goal of this study was to characterize the changes of quantitative diffusion indices along white matter tracts in the developing rabbit brains. Along-tract method analyzes the quantitative diffusion indices associated with these virtual dissections in a way that is parameterized along the curving axes of the tract spines, instead of the more typical method of averaging this variation into a single mean estimate for each tract. In this study, DTI data of in vivo rabbit brains (4 weeks to 40 weeks) were acquired and analyzed. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) in the regions of interest (ROIs) and along tracts were generated and compared across the ages. In our results, DTI tractography of the important white matter tracts, such as hippocampus, corpus callosum, and olfactory tract, showed refinement in regional tract architecture with maturation. Both regional and along-tract diffusion indices revealed these white matter tracts change during mature period.
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