The complex structural organization of the white matter bundles in a living human brain can be depicted in great detail with state-of-the-art diffusion magnetic resonance imaging (MRI), presently the only neuroimaging approach that is able to non-invasively map neuroanatomical architectures. In this review article, we introduce several diffusion MRI methods from a technical perspective, and examine topics including their theoretical basis, how fiber orientations are estimated, how white matter tracts are reconstructed, and measures of brain network analysis. In principle, the attenuation of the MR signal after the application of motion-sensitive magnetic gradients is the result of spin diffusion. These direction-dependent diffusion MR signals can be used to estimate fiber orientations by measuring intravoxel diffusion coherence. Continuous white matter tracts can be further reconstructed using fiber-tracking algorithms, also referred to as tractography. Finally, a whole-brain structural network can be obtained and analyzed using graph theory. These techniques reinforce the importance of using diffusion MRI in neuroscience research and clinical applications. Although further technical development of diffusion MRI methods is still necessary for improved accuracy and robustness, they have undoubtedly opened a new window for investigating anatomical connectivity and brain connectomics in a non-invasive yet quantitative way.
Date:
2013-04
Relation:
Journal of Neuroscience and Neuroengineering. 2013 Apr;2(2):104-118.
