Paramagnetic rim lesions are highly specific for multiple sclerosis in real-world data

Area of Science:

• Neurology
• Radiology
• Neuroimmunology

Background:

• Paramagnetic rim lesions (PRLs) represent chronic, low-grade intraparenchymal brain inflammation in multiple sclerosis (MS).
• PRLs are associated with increased MS disease severity and may assist in diagnosis.

Purpose of the Study:

• To evaluate the specificity and sensitivity of PRLs for differentiating MS from other neurological conditions.
• To assess the diagnostic utility of PRLs using real-world clinical and imaging data.

Main Methods:

• Retrospective analysis of a longitudinal cohort with prospectively collected data.
• MRI scans (3-T) with T2*-weighted sequences and susceptibility post-processing were reviewed for PRLs.
• PRLs were classified as 'definite', 'probable', or 'possible' based on consensus criteria.

Main Results:

• Analysis included 574 patients: 473 with MS, 53 with non-inflammatory neurological disease, and 48 with other inflammatory neurological disease.
• 'Definite' or 'probable' PRLs demonstrated 98% specificity in distinguishing MS from mimics, with 36% sensitivity.
• Interrater agreement for definite/probable PRL identification was almost perfect.

Conclusions:

• PRLs offer high specificity for diagnosing multiple sclerosis, supporting clinical evaluation.
• The modest sensitivity of PRLs restricts their use as standalone diagnostic markers.
• Inclusion of 'possible' PRLs significantly reduces specificity, necessitating cautious interpretation to avoid misdiagnosis.