Paramagnetic Rim Sign in Radiologically Isolated Syndrome

Abstract

Individuals with radiologically isolated syndrome (RIS) have incidental magnetic resonance imaging (MRI) abnormalities suggestive of multiple sclerosis (MS). 1 Recent studies using susceptibility-based imaging have shown that a subgroup of chronic MS white matter lesions (WMLs) have a rim of paramagnetic susceptibility-associated signal loss at the lesion edge, the paramagnetic rim sign (PRS), that is associated with the presence of iron inside phagocytes, which indicates chronic, active demyelination. The objective of this study was to determine whether patients with RIS have WMLs that are positive for PRS (PRS+).