In MS, iron-ringed lesions may add to imaging toolkit

STOCKHOLM – The presence of an iron ring around a brain lesion suspicious for multiple sclerosis (MS) may provide a promising adjunct to evolving magnetic resonance imaging techniques to track disease activity and progression, according to research presented at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis.

^{Kari Oakes/MDedge News}

Dr. Margareta Clarke

Using a conventional 3 Tesla magnetic resonance imaging (MRI) scanner, Margareta Clarke, PhD, and colleagues were able to identify iron rings (also called iron rims) and the central vein sign, and saw that both lesion characteristics were more common in MS patients than in those without MS.

“Routine two-dimensional 3 Tesla MRI with susceptibility weighting can be used to successfully visualize central veins and iron rims,” said Dr. Clarke, speaking at an imaging-focused young investigators’ session at the meeting. “Also, the central vein sign findings from previous 3T studies are confirmed.”

Dr. Clarke, a research fellow at the Vall d’Hebron Research Institute in Barcelona, explained that iron is stored within oligodendrocytes and myelin within the brain. In up to 56% of MS lesions, a rim of iron is visible with susceptibility weighted MRI imaging, she said, adding that the iron rings around the lesions “are likely caused by iron-laden activated microglia and macrophages that accumulate on the edges of lesions.”

It had been known that when lesions are surrounded by iron rings, they are more likely to enlarge and become increasingly hypointense on T1 weighted MRI. In addition, patients with more disability are more likely to have iron-rimmed brain lesions, said Dr. Clarke, and iron rings are associated with chronic disease activity. “Iron rings are a proposed marker of continuing inflammation and tissue loss,” she added.