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Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
White matter lesions defined by diffusion tensor imaging in older adults.
Stephen A Back1, Christopher D Kroenke, Larry S Sherman
1Department of Pediatrics, Oregon Health and Science University, Portland, OR, USA.
Annals of Neurology
|September 10, 2011
Summary
White matter lesions in older adults are linked to vascular brain injury, showing increased free radical damage and oligodendrocyte precursor cells. These findings clarify mechanisms of age-related cognitive decline.
Area of Science:
- Neuroimaging
- Neuropathology
- Aging Research
Background:
- Mechanisms of age-related cognitive decline and white matter changes are not fully understood.
- Magnetic resonance imaging (MRI) detects white matter (WM) changes, but their cellular basis is unclear.
- Diffusion tensor imaging (DTI) can define WM lesions, often associated with vascular brain injury (VBI) and Alzheimer disease (AD).
Purpose of the Study:
- To investigate the cellular and molecular mechanisms of DTI-defined WM changes in older adults.
- To test if WM lesions in older adults result from VBI and involve free radical injury and oligodendrocyte lineage (OL) cell response.
- To correlate DTI metrics with biomarkers of injury and OL response.
Main Methods:
- Multimodal analysis of prefrontal cortex (PFC) WM from 25 autopsies.
- Ex vivo high-field DTI (11.7T) to measure fractional anisotropy (FA) and diffusivity (D(⊥)).
- Quantitative biomarkers for free radical injury, OL marker Olig2, and hyaluronan (HA).
Main Results:
- VBI was associated with lower FA and increased D(⊥), independent of AD.
- Free radical injury was elevated in VBI cases and inversely correlated with FA.
- Increased Olig2-positive cells in WM were associated with VBI and colocalized with HA.
Conclusions:
- DTI-defined WM lesions in older individuals involve free radical injury to myelin and neuroaxonal components.
- These lesions coincide with an expanded pool of oligodendrocyte precursor cells in HA-rich areas.
- Findings suggest VBI contributes to WM damage and altered OL response in aging.
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