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Updated: Jul 26, 2025
Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
Published on: February 19, 2021
Early Magnetic Resonance Imaging Features of New Paramagnetic Rim Lesions in Multiple Sclerosis
Kelly A Clark1,2, Abby R Manning1,2, Luyun Chen1,2
1Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Objective:
To determine early magnetic resonance imaging (MRI) features of new multiple sclerosis (MS) lesions that will develop into paramagnetic rim lesions (PRLs), which have been associated with progressive tissue injury in MS.
Methods:
New contrast-enhancing lesions observed on routine clinical MRI were imaged at 7 T within 4 weeks of observation, and 3 and 6 months later. The 6-month MRI was used to classify PRL status (PRL or non-PRL). The relationship between early lesion characteristics and subsequent PRL status was assessed using generalized linear mixed effects models. Random forest classification was performed to classify early predictors of subsequent PRL status.
Results:
From 93 contrast-enhancing lesions in 23 MS patients, 37 lesions developed into a PRL. In lesions that developed into PRLs compared with those that did not, the average lesion T1 on the initial 7 T MRI was 1994 ms compared with 1,670 ms (p-value <0.001), and the average volume was 168.7 mL compared with 44 mL (p-value <0.001) in lesions that did not. These volume differences were also found on 3 T scans (p-value <0.001), and for intensity-normalized T1 -w (p-value = 0.011) and fluid-attenuated inversion recovery (p-value = 0.005). The area under the receiver operating characteristic curve for the random forest classification with leave-one-out cross-validation was found to be 0.86 using initial 7 T features.
Interpretation:
New MS lesions that evolve into PRLs can be identified early in lesion evolution. These findings suggest that biological mechanisms underlying PRL development begin early, which has important implications for clinical trials targeting PRLs development and subsequent therapeutics. ANN NEUROL 2023;94:736-744.
Insights
Early MRI features can predict the development of paramagnetic rim lesions (PRLs) in multiple sclerosis (MS). Identifying these early indicators aids in understanding disease progression and developing targeted therapies for MS.
Area of Science:
- Neuroimaging
- Neurology
- Radiology
Background:
- Paramagnetic rim lesions (PRLs) in multiple sclerosis (MS) are associated with progressive tissue injury.
- Early identification of lesions that develop into PRLs is crucial for understanding MS pathology.
Purpose of the Study:
- To identify early magnetic resonance imaging (MRI) features that predict the development of paramagnetic rim lesions (PRLs) in new multiple sclerosis (MS) lesions.
- To investigate the relationship between initial lesion characteristics and subsequent PRL status.
Main Methods:
- New contrast-enhancing lesions in MS patients were imaged using 7 Tesla (7T) MRI within 4 weeks of observation, and at 3 and 6 months.
- Lesions were classified as PRL or non-PRL at 6 months.
- Generalized linear mixed effects models and random forest classification were used to analyze early lesion characteristics and predict PRL status.
Main Results:
- Of 93 contrast-enhancing lesions, 37 developed into PRLs.
- Lesions that became PRLs showed significantly higher initial T1 values (1994 ms vs 1670 ms) and larger volumes (168.7 mL vs 44 mL) on 7T MRI compared to non-PRL lesions.
- These differences in volume and intensity-normalized T1-weighted and fluid-attenuated inversion recovery signals were also significant on 3T scans.
- Random forest classification achieved an area under the receiver operating characteristic curve of 0.86 for predicting PRL status using initial 7T features.
Conclusions:
- Early MRI characteristics, particularly higher T1 values and larger volumes, can identify new MS lesions that will evolve into PRLs.
- These findings suggest that the biological processes leading to PRL development begin early in lesion evolution.
- Early identification of PRL precursors has significant implications for clinical trials and the development of targeted therapies for MS.
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