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Updated: Sep 7, 2025
Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
Published on: February 19, 2021
Spatial distribution of multiple sclerosis iron rim lesions and their impact on disability
Matthias Wittayer1, Claudia E Weber1, Michael Platten2
1Department of Neurology, Medical Faculty Mannheim and Mannheim Center of Translational Neurosciences (MCTN), Heidelberg University, Theodor-Kutzer-Ufer 1 - 3, Mannheim 68167, Germany.
Background:
In multiple sclerosis (MS), iron rim lesions (IRLs) on magnetic resonance imaging (MRI) have been suggested as an imaging marker of disease progression. However, the exact mechanisms how they contribute to disability are yet not completely known. Strategic lesion location may be an important factor concerning the impact of focal lesions on clinical disability. Therefore, the aim of this study was to investigate the spatial distribution of IRLs compared to non-IRLs and their impact on disability.
Methods:
We retrospectively identified 67 patients with at least one IRL on MRI and 67 age- and sex-matched patients without IRLs. We compared the spatial distribution of lesions between both groups and between IRLs and non-IRLs in patients with IRLs. Furthermore, we assessed the relationship between lesion localisation and disability on a voxel-by-voxel basis and investigated the impact on structural network disruptions.
Results:
Patients with IRLs had higher disability scores (median Expanded Disability Status Scale score (range): 3.0 (0 - 8.5) versus 1.5 (0 - 6.5); p = 0.001; median pyramidal functional system score (range): 1.0 (0 - 5) versus 0 (0 - 4); p = 0.003), significantly lower brain volumes (mean normal-appearing grey matter volume: 749.66 ± 60.58 versus 785.83 ± 53.71 mL; mean normal-appearing white matter volume: 723.58 ± 60.13 versus 753.25 ± 69.61 mL; mean deep grey matter volume: 33.21 ± 4.19 versus 35.85 ± 4.89 mL; p < 0.05 for all comparisons) and a significantly higher total T2 lesion volume (mean: 9.96 ± 11.6 versus 4.31 ± 8.9 mL; p < 0.001). We found no neuroanatomical regions that were more often affected by IRLs. Furthermore, comparing the overall network disruption in the IRL group, IRLs caused less network disruption/mL lesion size compared to non-IRLs (1.54% / mL versus 2.0% / mL; p < 0.05).
Conclusion:
IRLs are associated with higher disability scores. However, our results suggest that a higher disability is not explained by the sheer topography of IRLs or their network disruption.
Insights
Iron rim lesions (IRLs) in multiple sclerosis (MS) correlate with increased disability. However, their specific location and network impact do not fully explain this higher disability in patients with MS.
Area of Science:
- Neurology
- Radiology
- Neuroimmunology
Background:
- Iron rim lesions (IRLs) on MRI are potential markers for multiple sclerosis (MS) progression.
- The precise mechanisms linking IRLs to clinical disability remain unclear.
- Lesion location is a key factor in understanding focal lesion impact on disability.
Purpose of the Study:
- To investigate the spatial distribution of IRLs compared to non-IRLs.
- To assess the impact of IRLs and their location on patient disability.
- To examine the relationship between lesion localization and structural network disruptions.
Main Methods:
- Retrospective analysis of 67 MS patients with IRLs and 67 matched controls without IRLs.
- Comparison of lesion spatial distribution between groups and lesion types (IRLs vs. non-IRLs).
- Voxel-based analysis of lesion location, disability, and structural network integrity.
Main Results:
- Patients with IRLs exhibited higher disability scores and lower brain volumes (grey and white matter).
- IRLs were associated with significantly higher total T2 lesion volume.
- No specific neuroanatomical regions were preferentially affected by IRLs; IRLs caused less network disruption per lesion volume than non-IRLs.
Conclusions:
- IRLs are significantly associated with increased disability in MS patients.
- The topography of IRLs and their direct network disruption do not fully account for the observed higher disability levels.
