The joint occurrence of SELs and PRLs, two MRI markers of chronic active lesions in MS, was linked to greater clinical progression in patients with MS.

Approximately 15% to 30% of the lesions that occur in patients with multiple sclerosis display chronic inflammatory activity. These active lesions are believed to indicate the progression of the disease outside of relapse events. Slowly expanding lesions (SELs) and paramagnetic rim lesions (PRLs) are used as markers when considering MRI findings in the calculation of disease progress.

In an observational study published in Multiple Sclerosis Journal, Alberto Calvi, MD, PhD, and colleagues sought to examine the relationship between SELs and PRLs in 61 patients with MS and to determine whether the presence of both lends insight into greater clinical disease progression. To do so, the research team used MRI, including baseline susceptibility-weighted imaging and longitudinal T1 and T2-weighted scans. PRLs were visually identified whereas SELs were computed using deformation field maps. Changes in Expanded Disability Status Scale (EDSS) scores were assessed between baseline and the last MRI session over a median follow-up time of 3.2 years.

The research team found SELs were more common than PRLs (92% [n=56] vs 56% [n=34]), but when both types of lesions were present (51% [n=31]), patients experienced more severe disease progression, indicated by greater increases in EDSS scores over time (beta, 0.15/year; 95% CI, 0.04-0.27; P=0.009; Figure). Thus, they concluded that the dual occurrence of SELs and PRLs could serve as a predictor of MS severity in disease progression.

Dr. Calvi discussed the findings of the study with Physician’s Weekly.

PW: Why did you feel this topic needed exploration?

Dr. Calvi: Pathological studies have shown that in MS there is an accumulation of chronic active lesions. There is a need to find new and advanced imaging markers using MRI, which is an accessible tool for patients to investigate this subtype of MS plaques.

What should practicing physicians understand about your findings?

In our study, we found that SELs are frequent in MS and are associated with worsening of the disease. This type of lesion can be easily detected with simple MRI sequences.

How can these findings be incorporated into practice?

SELs can be acquired by computing longitudinally the deformation inside lesion masks; this can be automatically acquired through an algorithm assessing the constant enlargement of the lesion over time and from the center of the lesion toward the periphery.

What would you like future research to be focused on?

In the future, we should assess how the accumulation of chronic active lesions is associated pathogenetically with the progression of the disease, as it seems to be a multifactorial process involving several factors.

Is there anything else you’d like to mention?

MS has changed enormously over the past decades due to the improvement of tools to assess the disease, thus there is a need to explore combinations of markers (eg, imaging, blood-derived, genetics) to understand the evolution of the disease and factors associated with its progression.