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Published on: April 14, 2014
MRI lesion volume heterogeneity in primary progressive MS in relation with axonal damage and brain atrophy
D Pelletier1, S J Nelson, J Oh
1Department of Neurology, University of California at San Francisco, San Francisco, CA, USA. danp@itsa.ucsf.edu
Objectives:
To investigate whether axonal damage in primary progressive (PP) multiple sclerosis (MS), as measured by proton magnetic resonance spectroscopy (HMRS) imaging and brain atrophy, is a function of T2 weighted brain lesion volume.
Methods:
34 PP MS patients were divided into two categories: low (<3 cm(3), n = 18) or high (>or=3 cm(3), n = 16) T2 lesion load (LL). An Index of Brain Atrophy (IBA) was calculated and HMRS metabolite ratios were derived from a central brain area centred at the corpus callosum.
Results:
Patient groups did not differ with regard to clinical characteristics and showed lower mean IBA and mean N-acetylaspartate:creatinine (NAA:Cr) ratios compared to healthy controls.
Conclusion:
PP patients with low and high brain T2LL have detectable brain atrophy and NAA:Cr reduction compared to healthy controls. In PP MS, T2 lesions alone are insufficient to explain the presence of brain atrophy and decrease in NAA:Cr.
Insights
In primary progressive multiple sclerosis (PP MS), brain atrophy and reduced N-acetylaspartate (NAA) levels are present regardless of T2 lesion load. However, T2 lesions alone do not fully explain these changes.
Area of Science:
- Neuroimaging
- Neurology
- Biochemistry
Background:
- Primary progressive multiple sclerosis (PP MS) is characterized by gradual neurological decline.
- Axonal damage and brain atrophy are key pathological features in PP MS.
- The relationship between T2-weighted brain lesion volume and axonal damage is not fully understood.
Purpose of the Study:
- To determine if axonal damage, measured by proton magnetic resonance spectroscopy (¹H MRS) and brain atrophy, correlates with T2-weighted brain lesion volume in PP MS.
- To compare brain atrophy and metabolite ratios between PP MS patients with low and high T2 lesion loads.
Main Methods:
- Thirty-four PP MS patients were categorized into low (<3 cm³) and high (≥3 cm³) T2 lesion load groups.
- Brain atrophy was quantified using an Index of Brain Atrophy (IBA).
- ¹H MRS metabolite ratios, specifically N-acetylaspartate to creatinine (NAA:Cr), were measured in a central brain region.
Main Results:
- No significant differences in clinical characteristics were observed between the low and high T2 lesion load groups.
- PP MS patients exhibited lower mean IBA and NAA:Cr ratios compared to healthy controls.
- Both low and high T2 lesion load groups showed detectable brain atrophy and reduced NAA:Cr ratios.
Conclusions:
- Brain atrophy and reduced NAA:Cr are present in PP MS patients irrespective of T2 lesion load.
- T2 lesion volume alone is insufficient to account for the observed brain atrophy and NAA:Cr reduction in PP MS.
- These findings suggest other factors contribute to neurodegeneration in PP MS beyond T2 lesion burden.
