J Magn Reson Imaging. 2024 Sep 6. doi: 10.1002/jmri.29583. Online ahead of print.

ABSTRACT

BACKGROUND: Multiple sclerosis (MS) paramagnetic rim lesions (PRLs) are markers of chronic active biology and exhibit complex iron and myelin changes that may complicate quantification when using conventional MRI approaches.

PURPOSE: To conduct a multiparametric MRI analysis of PRLs.

STUDY TYPE: Retrospective/longitudinal.

SUBJECTS: Ninety-five progressive MS subjects with at least one persistent PRL who were enrolled in the CONSONANCE trial.

FIELD STRENGTH/SEQUENCE: 3-T/Susceptibility-weighted, T1-weighted, T2-weighted, and fluid-attenuated inversion recovery.

ASSESSMENT: Acute/chronic PRLs and non-PRLs were measured at screening, 24, 48, and 96 weeks using quantitative magnetic susceptibility (QS), R2*, and standardized T1w/T2w ratio (sT1w/T2w). PRL analyses were performed for whole lesion, core, and rim. The correlations between PRL core and rim sT1w/T2w, QS, and R2* were assessed.

STATISTICAL TESTS: Linear mixed models. A P-value <0.05 was considered significant.

RESULTS: There was a significant decrease in sT1w/T2w (-0.24 ± -5.3 × 10^-3) and R2* (-3.6 ± 2.2 Hz) but a significant increase in QS (+21 ± 1.3 ppb) using whole-lesion analysis of chronic PRLs compared to non-PRLs at screening. Tissue damage accumulated at the 96-week time point was more evident in acute/chronic PRLs compared to acute/chronic non-PRLs (ΔsT1w/T2w = -0.21/-0.24 ± 0.033/0.0053; ΔR2* = -4.4/-3.6 ± 1.4/2.2 Hz). New, acute PRL sT1w/T2w significantly increased in lesion core (+4.3 × 10^-3 ± 1.2 × 10^-4) and rim (+5.6 × 10^-3 ± 1.2 × 10^-4) 24 weeks post lesion inception, suggestive of partial recovery. Chronic PRLs, contrastingly, showed significant decreases in sT1w/T2w over the initial 24 weeks for both core (-2.1 × 10^-4 ± 2.0 × 10^-5) and rim (-2.4 × 10^-4 ± 2.0 × 10^-5), indicative of irreversible tissue damage. Significant positive correlations between PRL core and rim sT1w/T2w (R² = 0.53), R2* (R² = 0.69) and QS (R² = 0.52) were observed.

DATA CONCLUSION: Multiparametric assessment of PRLs has the potential to be a valuable tool for assessing complex iron and myelin changes in chronic active PRLs of progressive MS patients.

LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 3.

PMID:39239775 | DOI:10.1002/jmri.29583