Abstract
ObjectivesIn multiple sclerosis (MS), iron rim lesions (IRLs) are indicators of chronic low-grade inflammation and ongoing tissue destruction. The aim of this study was to assess the relationship of IRLs with clinical measures and magnetic resonance imaging (MRI) markers, in particular brain and cervical cord volume.MethodsClinical and MRI parameters from 102 relapsing MS patients (no relapses for at least 6 months, no contrast-enhancing lesions) were included; follow-up data obtained after 12 months was available in 49 patients. IRLs were identified on susceptibility-weighted images (SWIs). In addition to standard brain and spinal cord MRI parameters, normalised cross-sectional area (nCSA) of the upper cervical cord was calculated.ResultsThirty-eight patients had at least one IRL on SWI MRI. At baseline, patients with IRLs had higher EDSS scores, higher lesion loads (brain and spinal cord), and lower cortical grey matter volumes and a lower nCSA. At follow-up, brain atrophy rates were higher in patients with IRLs. IRLs correlated spatially with T1-hypointense lesions.ConclusionsRelapsing MS patients with IRLs showed more aggressive MRI disease characteristics in both the cross-sectional and longitudinal analyses.Key Points• Multiple sclerosis patients with iron rim lesions had higher EDSS scores, higher brain and spinal cord lesion loads, lower cortical grey matter volumes, and a lower normalised cross-sectional area of the upper cervical spinal cord.• Iron rim lesions are a new lesion descriptor obtained from susceptibility-weighted MRI. Our data suggests that further exploration of this lesion characteristic in regard to a poorer prognosis in multiple sclerosis patients is warranted.
Highlights
In multiple sclerosis (MS), magnetic resonance imaging (MRI) allows the requested demonstration of dissemination in time and space [1] and plays an important role in disease monitoring
We investigated the association between iron rim lesions” (IRLs) with clinical measures and MRI readouts, in particular brain and cervical spinal cord volumes
Even though the in-plane voxel dimensions of the axial susceptibility-weighted images (SWIs) used in our study were larger compared to previous studies [6, 7], we found IRLs in ~ 40% of MS patients, a finding that is comparable to autopsy [29, 30] and MRI studies [28, 31], making SWI an interesting candidate for the detection of IRLs in a clinical setting
Summary
In multiple sclerosis (MS), magnetic resonance imaging (MRI) allows the requested demonstration of dissemination in time and space [1] and plays an important role in disease monitoring. There has been an increasing interest in “chronic active” MS lesions that are associated with higher disease severity and ongoing tissue destruction as an imaging biomarker of disease progression [3,4,5,6,7,8]. Chronic active lesions are characterised by a self-sustained low degree of chronic inflammation, active myelin breakdown, neurodegeneration, axonal loss, and progressive tissue matrix damage driven by a rim of iron-laden activated microglia/macrophages and reactive astrocytes at the lesion edge [4, 9]. Previous combined MRI/post-mortem studies demonstrated that these pathophysiological conditions can be visualised as hypointense rims on susceptibility-weighted imaging (SWI) [4, 6, 7], termed “iron rim lesions” (IRLs) [6, 10]. While previous studies reported an association between IRLs and brain volumes [6], the relationship between IRLs and spinal cord volumes has not been investigated until now
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