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Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
A study of the mechanisms of normal-appearing white matter damage in multiple sclerosis using diffusion tensor
Olga Ciccarelli1, David J Werring, Gareth J Barker
1NMR Research Unit, Institute of Neurology, National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK.
Abstract:
Diffusion tensor imaging (DTI) investigates brain tissue microstructure in vivo. In multiple sclerosis (MS) Wallerian degeneration of axons traversing focal lesions is a potential mechanism of damage in normal-appearing white matter. In vivo evidence for this hypothesis is limited. The present study investigated the relationship between DTI-derived indices in the normal-appearing corpus callosum (CC) and the lesion loads (LLs) in connected cerebral regions. DTI was performed in 39 MS patients and in 21 age-matched controls. Fractional anisotropy (FA) and mean diffusivity (MD) were estimated in the genu, body and splenium of CC. Patients showed lower FA and higher MD in the CC than controls and both correlated with the total LL (r = -0.56 and r = 0.54, p < 0.0001). The LL of individual cerebral lobes correlated with both FA and MD in the corresponding callosal regions, with the body showing the strongest correlations with frontal and parietal LL (p < 0.0001). The strong correlations between DTI indices in the CC and the extent of lesions in connected brain regions support the hypothesis that Wallerian degeneration of axons transected by remote, but connected focal lesions, is an important pathogenic mechanism of damage in MS.
Insights
Diffusion tensor imaging reveals Wallerian degeneration in multiple sclerosis (MS) normal-appearing white matter. Lesion load in connected brain regions strongly correlates with microstructural changes in the corpus callosum.
Area of Science:
- Neuroimaging
- Neuroscience
- Medical Physics
Background:
- Multiple sclerosis (MS) involves white matter damage, with Wallerian degeneration proposed as a key mechanism in normal-appearing white matter.
- In vivo evidence for Wallerian degeneration in MS, particularly its link to remote lesions, remains limited.
Purpose of the Study:
- To investigate the relationship between diffusion tensor imaging (DTI) derived indices in the normal-appearing corpus callosum (CC) and lesion loads (LLs) in connected cerebral regions in MS patients.
- To provide in vivo evidence for Wallerian degeneration as a pathogenic mechanism in MS.
Main Methods:
- Diffusion tensor imaging (DTI) was performed on 39 MS patients and 21 healthy controls.
- Fractional anisotropy (FA) and mean diffusivity (MD) were calculated in the genu, body, and splenium of the CC.
- Correlations between CC DTI indices and total and regional lesion loads were analyzed.
Main Results:
- MS patients exhibited significantly lower FA and higher MD in the CC compared to controls.
- Both FA and MD in the CC showed strong correlations with total lesion load (r = -0.56 and r = 0.54, respectively; p < 0.0001).
- Lesion load in specific cerebral lobes correlated with DTI indices in corresponding CC regions, with the CC body showing the strongest associations with frontal and parietal LLs.
Conclusions:
- The findings support the hypothesis that Wallerian degeneration, caused by axons transected by remote lesions, contributes significantly to white matter damage in MS.
- DTI-derived indices in the normal-appearing CC are sensitive to the burden of disease and connected lesion load in MS.
- This study provides robust in vivo evidence for the role of Wallerian degeneration in MS pathogenesis.
