“Identifying an accurate prognostic biomarker in individuals with multiple sclerosis (MS) is crucial for helping clinicians [utilize] early disease-modifying therapies (DMTs),” according to Amjad AlTokhis, PhD-candidate and colleagues. “The role of iron rims surrounding white matter lesions (IRL) has generated a lot of interest as they are suggested to predict a more severe disease course. Only small longitudinal cohorts of patients with and without IRL have been reported so far to establish the strength of these associations.”
Assessing the Presence of IRLs
To close the information gap, AlTokhis and colleagues recruited 91 patients with MS between 2008 and 2013 to undergo a 7T MRI including SWI-filtered phase sequence. The researchers calculated Age Related Multiple Sclerosis Score (ARMSS) for all participants at the time of their MRI scan and during their last clinical follow-up. They also used filtered phase images to assess the presence or IRLs. “Our aim [was] to assess if the presence and number of [initial] iron rim lesions are associated with worse long-term disability,” said AlTokhis. At baseline, 34 participants had relapsing-remitting MS (RRMS), 22 had clinically isolated syndrome (CIS), 18 had primary progressive MS (PPMS), and 17 had secondary progressive MS (SPMS).
AlTokhis and team identified at least one IRL in 46% of patients, including 71% of those with SPMS, 50% of those with CIS, 38% of those with RRMS, and 38% of those with PPMS. Among all participants, 30% had one to three IRLs and 16% had four or more. Those with SPMS had more IRLs—58 among 12 patients—than those with CIS or PPMS, whereas those with PPMS had fewer IRLs than those with CIS or RRMS.
IRLs Connected With Long-Term Disability
Based on ARMMS findings, baseline disease severity was significantly higher in participants with IRLs (6.7) than in those without (5.0); total participants had a median baseline ARMSS of 5.4. Among participants with CIS or RRMS, 18 progressed to SPMS (56% IRL+) and 24 did not (33% IRL+) at a median clinical follow-up of 9 years. Median ARMSS score was also higher at follow-up among patients with IRLs (7.3) than among those without IRLs (6.3). “We detected a significant positive correlation between the number of lesions with IRL and worsening of ARMSS,” wrote AlTokhis and colleagues.
The study findings “could support the use of iron rim lesions as an imaging biomarker for disease severity and worse prognosis,” said AlTokhis, adding that the “data suggest that the presence and number of iron rim lesions hold a prognostic value for long-term disability in MS, especially the presence of four or more rims.”