Yi-Wen Peng1, Yong-Jheng Wun2, Cheng-Hung Lai1, Jun-Cheng Weng2,3
1Department of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan; 2School of Medical Imaging & Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan; 3Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung, Taiwan
The brain is extraordinarily complex, and yet its origin is a simple tubular structure. Characterizing its 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 imaging (DTI), a non-invasive method of magnetic resonance imaging (MRI), is sensitive to structural ordering in brain tissue particularly in the white matter tracts. Diffusion anisotropy changes with demyelinating diseases and also with neural development. In the animal studies, however, only ex vivo brains have been studied. Therefore, the goal of this study was to study developmental changes in regional diffusion anisotropy and white matter fiber tract maturation of in vivo rabbit brains. In this study, DTI data of in vivo rabbit brains (4 weeks to 24 weeks) were acquired and analyzed. Normalized trace apparent diffusion coefficient (ADC), generalized fractional anisotropy (GFA), R2 mapping and fiber tracts were generated and compared across the ages. Our results showed that color maps of diffusion indices, R2 mapping, and 3D tractography revealed that important white matter tracts, such as the olfactory tract, corpus callosum and hippocampus, become apparent during mature period. Regional DTI tractography of the white matter tracts showed refinement in regional tract architecture with maturation. The white matter anisotropy and R2 values increased with age, and the diffusion coefficient decreased with age.