paramagnetic rim lesions
Also written as: PRLs
MS lesions with iron-laden activated microglia at their borders, visible on susceptibility-weighted MRI.
Full Definition
Paramagnetic rim lesions (PRLs) are a subset of multiple sclerosis lesions characterized by a hypointense rim on susceptibility-weighted imaging, representing iron accumulation in activated microglia and macrophages at the lesion edge. These lesions are associated with chronic active inflammation, slower repair, and more severe tissue damage. PRLs are considered a marker of aggressive MS disease and are associated with faster disability progression. They can persist for years and represent sites of ongoing inflammatory activity even when lesions appear inactive on conventional MRI sequences.
Usage
Usage note: Requires susceptibility-weighted imaging; associated with poor prognosis.
In Context
- "The patient had multiple paramagnetic rim lesions indicating chronic active inflammation." — MRI interpretation
- "PRLs on SWI sequences correlated with faster disability progression." — Clinical research findings