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Updated: Jun 11, 2025
Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
Published on: February 19, 2021
Clinical relevance of paramagnetic rim lesion heterogeneity in multiple sclerosis
Anna Stölting1, Colin Vanden Bulcke1,2, Serena Borrelli1,3
1Neuroinflammation Imaging Lab (NIL), Institute of NeuroScience, Université catholique de Louvain, Brussels, Belgium.
Objective:
Previous studies reveal heterogeneity in terms of paramagnetic rim lesions (PRL) associated tissue damage. We investigated the physiopathology and clinical implications of this heterogeneity.
Methods:
In 103 MS patients (72 relapsing and 31 progressive), brain lesions were manually segmented on 3T 3D-FLAIR and rim visibility was assessed with a visual confidence level score (VCLS) on 3D-EPI phase. Using T1 relaxation time maps, lesions were categorized in long-T1 and short-T1. Lesion age was calculated from time of first gadolinium enhancement (N = 84 lesions). Results on clinical scores were validated in an extended cohort of 167 patients using normalized T1w-MPRAGE lesion values.
Results:
Rim visibility (VCLS analysis) was associated with increasing lesional T1 (P/PFDR < 0.001). Of 1680 analyzed lesions, 427 were categorized as PRL. Long-T1 PRL were older than short-T1 PRL (average 0.8 vs. 2.0 years, P/PFDR = 0.005/0.008), and featured larger lesional volume (P/PFDR < 0.0001) and multi-shell diffusion-measured axonal damage (P/PFDR < 0.0001). The total volume of long-T1-PRL versus PRL showed 2× predictive power for both higher MS disability (EDSS; P/PFDR = 0.003/0.005 vs. P/PFDR = 0.042/0.057) and severity (MSSS; P/PFDR = 0.0006/0.001 vs. P/PFDR = 0.004/0.007). In random forest, having ≥1 long-T1-PRL versus ≥4 PRL showed 2-4× higher performance to predict a higher EDSS and MSSS. In the validation cohort, long-T1 PRL outperformed (~2×) PRL in predicting both EDSS and MSSS.
Interpretation:
PRL show substantial heterogeneity in terms of intralesional tissue damage. More destructive, likely older, long-T1 PRL improve the association with MS clinical scales. This PRL heterogeneity characterization was replicated using standard T1w MRI, highlighting its potential for clinical translation.
Insights
Older, more destructive paramagnetic rim lesions (PRL) in multiple sclerosis (MS) are associated with greater disability. Characterizing PRL heterogeneity using T1w MRI may improve clinical prediction and translation.
Area of Science:
- Neuroimaging
- Radiology
- Neurology
Background:
- Paramagnetic rim lesions (PRL) in multiple sclerosis (MS) exhibit heterogeneous tissue damage.
- Understanding this heterogeneity is crucial for assessing disease progression and clinical outcomes.
Purpose of the Study:
- To investigate the pathophysiology and clinical implications of heterogeneity in paramagnetic rim lesions (PRL) in MS.
- To characterize lesion age and tissue damage within PRL using advanced MRI techniques.
Main Methods:
- Manual segmentation of brain lesions in 103 MS patients using 3T 3D-FLAIR and 3D-EPI phase imaging.
- Categorization of lesions into long-T1 and short-T1 based on T1 relaxation time maps.
- Assessment of lesion age and validation in an extended cohort using T1w-MPRAGE.
Main Results:
- Rim visibility correlated with increased lesional T1 relaxation times.
- Long-T1 PRL were older, larger, and showed more axonal damage than short-T1 PRL.
- Long-T1 PRL volume significantly predicted higher MS disability (EDSS) and severity (MSSS), outperforming total PRL volume.
Conclusions:
- PRL display significant heterogeneity in intralesional tissue damage, with long-T1 PRL representing older, more destructive lesions.
- Characterizing PRL heterogeneity, particularly long-T1 PRL, enhances association with MS clinical scales.
- This characterization is reproducible with standard T1w MRI, suggesting clinical utility.
