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Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
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Fixel-Based Analysis Reveals Detailed White Matter Changes in Semantic Dementia
Maria Luisa Mandelli1, Yann Cobigo1, Ilaria Perretti2
1University of California San Francisco.
Research Square
|June 30, 2025
Summary
Fixel-based analysis (FBA) offers a more detailed view of white matter damage in semantic dementia (SD) than traditional methods, revealing widespread pathway involvement and aiding in understanding disease progression.
Area of Science:
- Neuroimaging
- Neuroscience
- Medical Imaging
Background:
- Characterizing white matter (WM) microstructure is crucial for understanding neurodegenerative diseases like semantic dementia (SD).
- Traditional methods like tract-based spatial statistics (TBSS) using diffusion-tensor imaging (DTI) assume single fiber populations per voxel, limiting sensitivity to complex WM architecture.
- Fixel-based morphometry (FBM) analyzes multiple fiber populations (fixels) per voxel, offering a more nuanced approach.
Purpose of the Study:
- To compare the efficacy of TBSS and Fixel-based analysis (FBA) in detecting WM alterations in SD variants.
- To identify specific white matter tracts affected by anterior temporal lobe (ATL) atrophy in semantic dementia.
Main Methods:
- Multi-shell diffusion MRI data were acquired from patients with semantic-variant primary progressive aphasia (svPPA) and semantic-behavioral fronto-temporal dementia (sbvFTD), along with healthy controls.
- Both TBSS-DTI and whole-brain FBA were applied to analyze fiber-specific metrics (density, cross-section) and conventional DTI measures.
Main Results:
- Both TBSS and FBA confirmed damage in ATL-connected tracts, including the uncinate fasciculus and inferior longitudinal fasciculus.
- FBA identified additional affected pathways not detected by TBSS, such as the tapetum, anterior commissure, and connections to the parahippocampal gyrus and amygdala.
Conclusions:
- Fixel-based analysis (FBA) provides a more comprehensive map of WM degeneration in semantic dementia compared to TBSS.
- FBA's ability to detect early changes in commissural and mesial-temporal pathways enhances understanding of disease spread.
- These findings highlight potential targets for monitoring and therapeutic interventions in semantic dementia.
Keywords:
anterior commissureanterior temporal lobediffusion brain imagingfixel-based analysissemantic dementiatract-based spatial statisticswhite matter changesMore Related Videos
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