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Updated: Apr 15, 2026
Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Age-related microstructural differences quantified using myelin water imaging and advanced diffusion MRI
Thibo Billiet1, Mathieu Vandenbulcke2, Burkhard Mädler3
1Translational MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium; Department of Radiology, University Hospitals Leuven, Leuven, Belgium; Medical Imaging Research Center (MIRC), Leuven, Belgium; Leuven Research Institute for Neuroscience & Disease (LIND), Leuven, Belgium.
Abstract:
Age-related microstructural differences have been detected using diffusion tensor imaging (DTI). Although DTI is sensitive to the effects of aging, it is not specific to any underlying biological mechanism, including demyelination. Combining multiexponential T2 relaxation (MET2) and multishell diffusion MRI (dMRI) techniques may elucidate such processes. Multishell dMRI and MET2 data were acquired from 59 healthy participants aged 17-70 years. Whole-brain and regional age-associated correlations of measures related to multiple dMRI models (DTI, diffusion kurtosis imaging [DKI], neurite orientation dispersion and density imaging [NODDI]) and myelin-sensitive MET2 metrics were assessed. DTI and NODDI revealed widespread increases in isotropic diffusivity with increasing age. In frontal white matter, fractional anisotropy linearly decreased with age, paralleled by increased "neurite" dispersion and no difference in myelin water fraction. DKI measures and neurite density correlated well with myelin water fraction and intracellular and extracellular water fraction. DTI estimates remain among the most sensitive markers for age-related alterations in white matter. NODDI, DKI, and MET2 indicate that the initial decrease in frontal fractional anisotropy may be due to increased axonal dispersion rather than demyelination.
Insights
Aging white matter shows microstructural changes detectable by diffusion tensor imaging (DTI). New MRI techniques suggest age-related frontal white matter changes stem from increased axonal dispersion, not demyelination.
Area of Science:
- Neuroimaging
- Biomedical Engineering
- Gerontology
Background:
- Diffusion Tensor Imaging (DTI) detects age-related brain changes but lacks specificity for underlying mechanisms like demyelination.
- Multiexponential T2 relaxation (MET2) and multishell diffusion MRI (dMRI) offer complementary insights into white matter microstructure.
Purpose of the Study:
- To investigate age-associated microstructural alterations in white matter using advanced dMRI models and MET2.
- To differentiate between axonal dispersion and demyelination as causes of age-related changes in white matter.
Main Methods:
- Acquired multishell dMRI and MET2 data from 59 healthy participants (aged 17-70).
- Analyzed whole-brain and regional correlations between age and metrics from DTI, DKI, NODDI, and MET2.
- Assessed myelin-sensitive MET2 metrics alongside diffusion parameters.
Main Results:
- DTI and NODDI showed increased isotropic diffusivity with age.
- Frontal white matter fractional anisotropy decreased linearly with age, accompanied by increased neurite dispersion and unchanged myelin water fraction.
- Diffusion Kurtosis Imaging (DKI) measures and neurite density correlated with myelin water fraction and water compartmentalization.
Conclusions:
- DTI remains sensitive to age-related white matter alterations.
- Findings suggest age-related decreases in frontal fractional anisotropy are primarily due to increased axonal dispersion, not demyelination.
- Combined dMRI and MET2 techniques provide a more specific understanding of aging brain microstructure.
