In the autumn issue of Lancet Neurology, an international consortium of imaging experts released updated consensus recommendations that could shorten the time it takes to diagnose multiple sclerosis (MS). The guidance—produced jointly by the Magnetic Resonance Imaging in MS (MAGNIMS) group, the Consortium of Multiple Sclerosis Centers (CMSC) and the North American Imaging in MS Cooperative (NAIMS)—adds new magnetic‑resonance imaging (MRI) markers to the McDonald diagnostic criteria, allowing clinicians to confirm MS in a single visit for many patients.
New MRI markers incorporated into the diagnostic criteria
The revised criteria embrace two imaging signatures that have been validated in recent peer‑reviewed studies. The “central vein sign” identifies a small vein running through the centre of a white‑matter lesion, a pattern that helps separate MS lesions from those caused by small‑vessel disease. The second addition, paramagnetic rim lesions (PRLs), are chronic active lesions that appear as a thin, iron‑rich border on susceptibility‑weighted MRI sequences. Research from the University at Buffalo’s Buffalo Neuroimaging Analysis Center (BNAC) has shown that PRLs are highly specific to MS and correlate with ongoing brain inflammation, relapse risk and future disability progression.
According to a 2024 consensus paper in The Lancet Neurology, the presence of even a single PRL or central‑vein‑sign lesion can fulfill the “dissemination in space” requirement of the McDonald criteria, eliminating the need for a separate “dissemination in time” demonstration that previously required waiting for new lesions to appear.
Why earlier diagnosis matters
Disease‑modifying therapies (DMTs) now available for MS can markedly slow the accumulation of disability, but they do not reverse existing neurodegeneration. Early initiation of treatment is therefore critical; the National Multiple Sclerosis Society notes that each year of untreated disease increases the risk of irreversible brain tissue loss. By enabling a definitive diagnosis at the first clinical encounter, the new criteria aim to reduce the months‑long “watchful‑waiting” periods that have traditionally delayed therapy.
“We now have powerful medicines that can halt disease activity, but none can wind the clock back,” said Michael G. Dwyer, associate professor of neurology at the Jacobs School of Medicine and a steering‑committee member of NAIMS. “Early, accurate diagnosis gives us the chance to start those therapies before irreversible damage sets in.”
Evidence behind the paramagnetic rim lesion
BNAC investigators, led by SUNY Distinguished Professor Robert Zivadinov, have published a series of studies linking PRLs to long‑term outcomes. In longitudinal cohorts followed for five and ten years, patients who harboured PRLs experienced faster accumulation of disability and more frequent relapses than those without. The lesions also showed a distinct pattern of iron deposition on quantitative susceptibility mapping, a technique that became widely available only in the past few years.
“Paramagnetic rim lesions are highly specific to MS and represent ongoing damage in the brain,” Dwyer explained. “While not every patient with MS will develop a rim lesion, their presence makes us far more confident of the diagnosis because they are rarely seen in other disorders.”
Beyond diagnostic value, PRLs shed light on disease mechanisms. Recent work suggests that dysregulated microglia—the brain’s resident immune cells—persistently surround chronic lesions, producing the iron‑rich rim even when peripheral immune activity is suppressed by DMTs. This insight aligns with a growing consensus that both peripheral immune infiltration and intrinsic CNS inflammation drive MS progression.
Broader public‑health implications
Accelerating diagnosis can lessen the long‑term burden of MS on patients and health systems. Earlier treatment reduces the likelihood of severe disability, which in turn lessens reliance on assistive devices, home care and costly hospitalizations. According to the World Health Organization, MS affects more than 2.8 million people worldwide, and even modest reductions in disability can translate into substantial economic savings.
However, the benefits hinge on equitable access to high‑resolution MRI. Many low‑resource settings lack the 3‑Tesla scanners needed for susceptibility‑weighted imaging, potentially widening disparities. Health‑policy makers are urged to consider investments in imaging infrastructure and training to ensure that the new criteria can be applied broadly.
Next steps for clinicians and researchers
Clinicians are now encouraged to incorporate the central‑vein sign and PRL assessment into routine MS work‑ups, especially when patients present with nonspecific symptoms such as blurry vision, tingling or fatigue. Radiology departments should adopt standardized acquisition protocols for susceptibility‑weighted sequences to reliably detect rim lesions.
Researchers continue to explore the biological drivers of PRLs. Ongoing trials are testing whether therapies that target microglial activation can reduce rim formation and improve outcomes, an effort that could further refine treatment strategies beyond peripheral immunosuppression.
Patients suspecting MS should seek a neurologist who can evaluate both clinical signs and the latest MRI biomarkers. Early referral and imaging can unlock timely access to disease‑modifying treatments, a crucial step toward preserving neurological function.
For more information on the updated diagnostic guidelines, see the Lancet Neurology consensus article. Additional background on MS epidemiology is available from the World Health Organization. Read more on Globally Pulse Health.
