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Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
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Tau-related white-matter alterations along spatially selective pathways
Qiuting Wen1, Shannon L Risacher1, Linhui Xie2
1Department of Radiology and Imaging Sciences, Indiana University School of Medicine,, Indianapolis, IN 46202, USA; Indiana Alzheimer Disease Research Center, Indiana University School of Medicine, Indianapolis, IN, USA.
Neuroimage
|November 15, 2020
Summary
Alzheimer's disease (AD) tau pathology is linked to white matter (WM) degeneration in vivo. This study reveals tau deposition correlates with microstructural WM changes, mirroring AD's spread pattern.
Area of Science:
- Neuroscience
- Radiology
- Pathology
Background:
- Alzheimer's disease (AD) is characterized by tau neurofibrillary tangles and progressive white matter (WM) degeneration.
- The mechanisms driving tau pathology spread and its in vivo association with WM alterations remain poorly understood.
- Previous studies relied on animal or postmortem data, limiting in vivo insights into tau-WM interplay.
Purpose of the Study:
- To explore the spatial pattern of tau-WM associations across the whole brain in vivo.
- To test the hypothesis that tau deposition is associated with WM microstructural alterations in a stereotypic pattern.
- To investigate the relationship between tau positron emission tomography (PET) and diffusion tensor imaging (DTI)/neurite orientation dispersion and density imaging (NODDI) metrics.
Main Methods:
- Sixty-two participants (cognitively normal, subjective cognitive decline, mild cognitive impairment) underwent tau PET and diffusion MRI (DTI and NODDI).
- A data-driven iterative searching (DDIS) approach combined with graph theory analyses was used to track tau-WM associations.
- Analyses explored spatial patterns of tau-WM associations, comparing them with amyloid-β PET signals.
Main Results:
- A distinct spatial pattern of tau-WM association was observed, mirroring the known spatiotemporal spread of tau pathology in AD.
- This pattern was not found between diffusion MRI and amyloid-β PET signals.
- Tau-related WM degeneration involved increased mean diffusivity (radial) and decreased intra-axonal volume fraction, suggesting lower axonal packing density and increased diffusion freedom.
Conclusions:
- In vivo findings demonstrate a significant association between cortical tau deposition and WM microstructural alterations.
- The observed association pattern aligns with postmortem Braak staging, supporting WM's role in the AD pathological cascade.
- Future longitudinal studies are needed to confirm tau pathology spread along connected brain areas.
