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Updated: Jul 5, 2026
Co-analysis of Brain Structure and Function using fMRI and Diffusion-weighted Imaging
Published on: November 8, 2012
Diffusion spectrum magnetic resonance imaging (DSI) tractography of crossing fibers
V J Wedeen1, R P Wang, J D Schmahmann
1Department of Radiology, MGH Martinos Center for Biomedical Imaging, Harvard Medical School, Charlestown, MA 02129, USA. van@nmr.mgh.harvard.edu
Abstract:
MRI tractography is the mapping of neural fiber pathways based on diffusion MRI of tissue diffusion anisotropy. Tractography based on diffusion tensor imaging (DTI) cannot directly image multiple fiber orientations within a single voxel. To address this limitation, diffusion spectrum MRI (DSI) and related methods were developed to image complex distributions of intravoxel fiber orientation. Here we demonstrate that tractography based on DSI has the capacity to image crossing fibers in neural tissue. DSI was performed in formalin-fixed brains of adult macaque and in the brains of healthy human subjects. Fiber tract solutions were constructed by a streamline procedure, following directions of maximum diffusion at every point, and analyzed in an interactive visualization environment (TrackVis). We report that DSI tractography accurately shows the known anatomic fiber crossings in optic chiasm, centrum semiovale, and brainstem; fiber intersections in gray matter, including cerebellar folia and the caudate nucleus; and radial fiber architecture in cerebral cortex. In contrast, none of these examples of fiber crossing and complex structure was identified by DTI analysis of the same data sets. These findings indicate that DSI tractography is able to image crossing fibers in neural tissue, an essential step toward non-invasive imaging of connectional neuroanatomy.
Insights
Diffusion spectrum imaging (DSI) tractography can map complex neural pathways, including crossing fibers, which diffusion tensor imaging (DTI) cannot resolve. This advancement enables more detailed non-invasive neuroimaging of brain connectivity.
Area of Science:
- Neuroimaging
- Diffusion MRI
- Neuroanatomy
Background:
- Diffusion MRI tractography maps neural pathways.
- Diffusion Tensor Imaging (DTI) has limitations in resolving complex fiber orientations within a single voxel.
- Diffusion Spectrum Imaging (DSI) was developed to overcome DTI's limitations.
Purpose of the Study:
- To demonstrate the capability of Diffusion Spectrum Imaging (DSI) tractography in imaging crossing fibers in neural tissue.
- To compare DSI tractography with Diffusion Tensor Imaging (DTI) for resolving complex neural structures.
Main Methods:
- Performed DSI on formalin-fixed macaque brains and healthy human brains.
- Constructed fiber tract solutions using a streamline procedure.
- Analyzed tractography data using the TrackVis interactive visualization environment.
Main Results:
- DSI tractography accurately depicted known fiber crossings in optic chiasm, centrum semiovale, and brainstem.
- DSI tractography identified fiber intersections in gray matter (cerebellar folia, caudate nucleus) and radial architecture in cerebral cortex.
- DTI analysis failed to identify these complex fiber crossings and structures in the same datasets.
Conclusions:
- DSI tractography successfully images crossing fibers in neural tissue.
- DSI tractography offers superior resolution for complex neural architecture compared to DTI.
- This represents a significant advancement for non-invasive imaging of connectional neuroanatomy.
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