WEST PALM BEACH, FLA. – , new research suggests.
Results from two studies add to the mounting evidence underscoring the importance of the imaging features, researchers noted. “Our 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 rim lesions,” said Amjad I. AlTokhis, School of Medicine, University of Nottingham, United Kingdom, and Division of Clinical Neuroscience, Nottingham University Hospitals NHS Trust, who was the lead author of both studies.
Importantly, the effect of the rim lesions on disability was greater than that of established prognostic biomarkers of T2 white matter lesion count and volume, she noted.
“This could support the use of iron rim lesions as an imaging biomarker for disease severity and worse prognosis,” said Dr. AlTokhis. “These findings also support that iron rim lesions might be clinically useful not only diagnostically but also for disease progression and predicting future disability in MS,” she added.
The findings were presented at the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum 2022.
Sign of aggressive disease?
Dozens of studies have linked rim lesions, which are also known as iron rim lesions because of their composition of iron-laden macrophages/microglia, to more severe disease course in MS, as well as to having potential as an important imaging biomarker for diagnosis. However, studies have often been limited to smaller longitudinal cohorts.
In the first study, Dr. AlTokhis and colleagues enrolled 91 patients with MS (56 women) between 2008 and 2013 for whom 7 Tesla (7T) MRI was available with SWI-filtered phase sequencing.
At baseline, among 42 patients with clinically isolated syndrome, 50% had one or more of the rim lesions. The corresponding rates were 38% among 34 patients with relapsing-remitting MS, 38% among 18 patients with primary-progressive MS, and as high as 71% among 17 patients with secondary-progressive MS (P < .05 vs. primary progressive MS and clinically isolated syndrome).
At a median follow-up of 9 years, 18 of the patients with clinically isolated syndrome and relapsing-remitting MS progressed to secondary progressive MS; and among them, 56% had at least one rim lesion.
Of 24 who did not progress to secondary progressive MS, only 33% had at least one rim lesion.
The median baseline level of disease severity in the entire cohort, as measured by Age-Related Multiple Sclerosis Score (ARMSS), was 5.4. However, the median score among patients with rim lesions was higher, compared with those without the lesions (ARMSS, 6.7 vs. 5.0).
After the median 9-year follow-up, disease severity remained higher among those with versus those without the lesions (ARMSS, 7.3 vs. 6.3).
Patients with rim lesions had more white matter lesions overall; and a further analysis surprisingly showed that the number of rim lesions was indeed associated with long-term disability (P = .005).
“Detecting four or more iron rim lesions could be a sign of more aggressive disease and disability – thus, possibly useful in earlier treatment and a potential target for therapies,” Dr. AlTokhis said.
“Also, for clinical practicality, [the number of] iron rim lesions had the most direct effect on disability compared to white matter lesion count and volume, supporting its role as an independent prognostic imaging biomarker,” she added.
Dr. AlTokhis noted that “detecting and counting rim lesions is much easier than assessing all white matter lesions, adding to the clinical utility of this sign.”