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Updated: May 5, 2026
Comprehensive Autopsy Program for Individuals with Multiple Sclerosis
Published on: July 19, 2019
The presence of a paramagnetic phase rim in multiple sclerosis is linked to lesion age: An exploratory study
Samuel Klistorner1, Tatiana Usnich2, Margareta A Clarke3
1Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
Background:
In relapsing-remitting multiple sclerosis (RRMS), smouldering inflammation at the rims of chronic active lesions is increasingly recognised as a key driver of disease progression. Paramagnetic rim lesions (PRLs), detected using susceptibility-weighted imaging, have emerged as a potential biomarker of this chronic inflammatory activity. However, their clinical relevance and relationship to lesion-specific features such as size and age remain poorly understood.
Objective:
To investigate the association between PRL presence and clinical/radiological measures of disease progression, and to explore how PRLs relate to lesion size and age.
Methods:
A retrospective study of 60 RRMS patients with over 5 years of magnetic resonance imaging data was conducted using susceptibility-weighted angiography. Lesions larger than 100 mm3 were analysed.
Results:
PRLs were present in 48% of patients and represented 13% of lesions. PRLs were significantly larger and more structurally damaged, with volume correlating with EDSS change and brain atrophy. All lesions formed within 5 years of imaging were PRLs. This finding was validated in two independent international cohorts. Moreover, the proportion of rim-positive lesions decreased as lesion age increased.
Conclusion:
PRLs are closely linked to lesion age and early development, supporting their role as a dynamic biomarker of lesion activity in multiple sclerosis.
Insights
Paramagnetic rim lesions (PRLs) indicate active inflammation in multiple sclerosis. These lesions are associated with disease progression and are more common in newly formed lesions, decreasing with age.
Area of Science:
- Neuroimaging
- Neurology
- Biomarker Discovery
Background:
- Smouldering inflammation in relapsing-remitting multiple sclerosis (RRMS) drives disease progression.
- Paramagnetic rim lesions (PRLs) detected via susceptibility-weighted imaging may indicate chronic inflammatory activity.
- The clinical relevance of PRLs and their relationship to lesion characteristics are not well understood.
Purpose of the Study:
- To examine the link between PRL presence and clinical/radiological markers of MS progression.
- To investigate the relationship between PRLs and lesion size and age.
Main Methods:
- Retrospective analysis of MRI data from 60 RRMS patients over 5 years.
- Utilized susceptibility-weighted imaging to detect PRLs.
- Analyzed lesions exceeding 100 mm³.
Main Results:
- PRLs were found in 48% of patients and 13% of lesions.
- PRLs were larger, more damaged, and their volume correlated with EDSS changes and brain atrophy.
- All lesions formed within 5 years were PRLs, a finding validated in international cohorts; PRL prevalence decreased with lesion age.
Conclusions:
- PRLs are strongly associated with lesion age and early development.
- PRLs serve as a dynamic biomarker for lesion activity in multiple sclerosis.
