Comparing a diffusion tensor and non-tensor approach to white matter fiber tractography in chronic stroke

Area of Science:

• Neuroimaging
• Neuroscience
• Medical Physics

Background:

• Diffusion tensor imaging (DTI) is limited by its inability to resolve complex intra-voxel fiber architectures.
• This limitation may affect the accuracy of white matter pathway reconstruction after stroke.
• Novel tensor-free methods like Constrained Spherical Deconvolution (CSD) offer improved characterization of intra-voxel diffusion behavior.

Purpose of the Study:

• To compare DTI and CSD tractography in reconstructing the corticospinal tract (CST) and corpus callosum (CC) in chronic stroke survivors.
• To test if CSD improves the detection of white matter abnormalities and their functional relevance compared to DTI.
• To evaluate the relationship between diffusion measures and post-stroke motor behavior.

Main Methods:

• Diffusion-weighted magnetic resonance imaging data from 27 chronic stroke participants and 12 healthy controls.
• Reconstruction of CST and CC pathways using both DTI- and CSD-based tractography.
• Calculation of diffusion metrics (FA, ADC, AD, RD) and tract properties (number, volume), followed by group comparisons and correlation with motor behavior.

Main Results:

• CSD identified more CC and CST tracts than DTI.
• CSD revealed differences in fractional anisotropy (FA) for the CC between stroke and control groups, which DTI did not.
• CSD detected more significant differences in CST pathways and their relation to motor behavior than DTI.

Conclusions:

• CSD-based tractography is superior to DTI for detecting white matter abnormalities in the CST and CC after stroke.
• CSD provides more sensitive and functionally relevant insights into white matter microstructure and its relationship with motor outcomes.
• Tensor-free diffusion modeling approaches like CSD hold significant potential for investigating post-stroke brain changes.