Novel MRI biomarkers, including cortical lesions, the central vein sign, and paramagnetic rim lesions, are highly specific for MS and can aid diagnosis in select clinical scenarios, particularly early in the disease course or in atypical presentations. When used with appropriate MRI sequences, these markers can improve diagnostic sensitivity while helping prevent misdiagnosis. In this episode, Casey Albin, MD, speaks with Jiwon Oh, MD, PhD, FRCPC, FAAN, author of the article "Diagnostic Neuroimaging...
Novel MRI biomarkers, including cortical lesions, the central vein sign, and paramagnetic rim lesions, are highly specific for MS and can aid diagnosis in select clinical scenarios, particularly early in the disease course or in atypical presentations. When used with appropriate MRI sequences, these markers can improve diagnostic sensitivity while helping prevent misdiagnosis.
In this episode, Casey Albin, MD, speaks with Jiwon Oh, MD, PhD, FRCPC, FAAN, author of the article "Diagnostic Neuroimaging Biomarkers for Multiple Sclerosis" in the Continuum® April 2026 Multiple Sclerosis and Related Disorders issue.
Dr. Albin is a Continuum® Audio interviewer, associate editor of media engagement, and an assistant professor of neurology and neurosurgery at Emory University School of Medicine in Atlanta, Georgia.
Dr. Oh is the medical director of the Barlo Multiple Sclerosis Program at St. Michael's Hospital and an associate professor at the University of Toronto in Toronto, Ontario, Canada.
Additional Resources
Read the article: Diagnostic Neuroimaging Biomarkers for Multiple Sclerosis
Subscribe to Continuum®: shop.lww.com/Continuum
Earn CME (available only to AAN members): continpub.com/AudioCME
Continuum® Aloud (verbatim audio-book style recordings of articles available only to Continuum® subscribers): continpub.com/Aloud
More about the American Academy of Neurology: aan.com
Social Media
facebook.com/continuumcme
@ContinuumAAN
Host: @caseyalbin
Full episode transcript available here
Dr Albin: Spend any time in a neurology conference, and you are certain to hear about the new central vein sign, which, as I learn, is not actually all that new. But have you heard about cortical lesions or these paramagnetic rim lesions? Because today I have the privilege of talking to Dr Jiwon Oh about her article, and we're going to unpack all these new biomarkers in MS.
Dr Jones: This is Dr Lyell Jones, editor in chief of Continuum. Thank you for listening to Continuum Audio. Be sure to visit the links in the episode notes for information about earning CME, subscribing to the journal, and exclusive access to interviews not featured on the podcast.
Dr Albin: Hello, this is Dr Casey Albin. Today I'm interviewing Dr Jiwon Oh about her article on diagnostic neuroimaging biomarkers for Multiple Sclerosis, which appears in the April 2026 Continuum issue on multiple sclerosis. Welcome to the podcast. Thank you so much for being here. I'd love to start by having you introduce yourself to our listeners.
Dr Oh: Thanks, Casey. Hi, everybody. My name is Jiwon Oh and I'm a neurologist, mainly an MS specialist at Saint Michael's Hospital at the University of Toronto, and I'm the medical director of our MS program.
Dr Albin: And you have written a really fantastic article that dives deep into some of the nitty gritty about these new diagnostic biomarkers that we find on the MRI that we're getting for our patients with multiple sclerosis. And I think we are going to get into a lot of that nitty gritty. How do we look for them? How do they improve our diagnostic specificity? This is really come a long way in shaping the advances for multiple sclerosis. And I'd kind of like to just start with the big picture. Like why do we need these more specific biomarkers?
Dr Oh: This set of diagnostic criteria in MS, it's actually a huge change in the field, and particularly for people like me who are really interested in developing new MRI measures, we're really, really excited because it's actually the first time since MRI was officially incorporated into the MS Diagnostic criteria, which was way back in 2001. It's the first time that we've actually been able to get newer, more advanced imaging measures beyond just simply detecting, new T2 lesions in the MS diagnostic criteria. So, it's a big moment in the field, and many of us are really excited about it in terms of why we need some of these newer, more specific imaging measures. Well, you know, diagnostic criteria always evolve over time for any disease state, and MS is one that we've recognized over the years. By the time someone actually presents with typical clinical symptoms and has diagnosed, whatever has been happening from a patho-biological standpoint has been happening probably for almost 5 to 10 years before that individual actually presents. And so, because of this recognition in the field and the fact that we're recognizing how important it is to first diagnose MS and then treat MS earlier and earlier, because we know that early treatment helps prevent more clinical outcomes. Diagnostic criteria over time have become much more permissive, meaning that we're doing everything that we can to try to facilitate a diagnosis of MS when we know that someone biologically has MS. But the problem with making diagnostic criteria more permissive, and it's obviously a good thing because you want to capture as many people with MS as early on as possible. The problem with making it permissive is there is this terrible risk of misdiagnosis. As clinicians, we all think we never make mistakes. But it turns out when you actually do studies, you do. And even at MS specialty centers, when studies have been done, 10% to 20% of people with MS are misdiagnosed. So, this is exactly why we need in diagnostic criteria that really help to facilitate a diagnosis. We need things that help us prevent misdiagnosis as well. And these are these specific imaging measures that have now been incorporated into the diagnostic criteria in many settings that will help to facilitate a diagnosis. But the really big perk is if you use them, you can help to prevent misdiagnosis as well.
Dr Albin: Yeah, that really shone through in your article that this was such a big step in towards being more specific about who were diagnosing. Also capturing more people, right? Trying to get those people that we, we don't want to miss because of all the things you say, you know, that allows them to accumulate more disability, have worse outcomes. Early diagnosis is so important. But I really did take away from your article just how critical these are and sharping our diagnostic acumen. And so just to jump right in, and you describe these three new biomarkers, these cortical lesions the central vein sign and paramagnetic rim lesions. And so just to kick things off let's start with cortical lesions I sort of conceptualize multiple sclerosis a disease of white matter. So, what's going on here?
Dr Oh: Yes. MS classically has always been described as a white matter disease. But it turns out when you look at brain and spinal cord tissue, as well as when you use kind of better sequences to actually look for lesions in the gray matter, it actually turns out there's a ton of lesions in the gray matter as well. And in fact, what's interesting is that regardless of whether it's the cortex or the deep gray matter, it's lesions within these areas that seem to have the highest relevance for clinical disability in MS. So, all this to say, of course, MS is a lesion that does affect white matter, but it also affects gray matter a lot. And maybe pathology within the gray matter is even more relevant to clinical disability. So, this is why we're really interested in being able to develop methods using MRI to more accurately visualize the gray matter, particularly the cortex, as well as deep gray matter structures like the thalamus. I should add the caveat that cortical lesions were actually included in the 2017 diagnostic criteria revisions, but they were included together with juxtacortical lesions, which are a typical area that MS lesions form. And so, this imaging measure, despite the fact that it is relatively novel and we consider it advanced, it hasn't been used that much only because it's not that easy to detect lesions within the cortex. And reasons for this include that you usually need higher field magnet platforms. And so, the typical clinical MRI scanners that are available kind of widely, regardless of whether you're at an academic center or a community center, are 1.5 Tesla magnets. And cortical lesions are actually really difficult to detect on those typical scanners. But when you get to like, say, three Tesla or seven Tesla, they're a lot easier to detect. But obviously that's a big hindrance to widespread use. And then you actually need very specialized sequences to adequately visualize cortical lesions. And these are not sequences that are usually collected for clinical purposes. So, it kind of requires convincing your radiologists that you need this additional sequence. And then it actually takes a lot of time and training to be able to adequately, accurately detect cortical lesions. So, despite the fact that it's actually very useful when you do have the appropriate MRI sequences and scanners to detect cortical lesions, even though they were incorporated into the 2017 criteria outside of specialty centers, they're not actually widely used. But when you do have the appropriate sequences, cortical lesions are actually pretty specific for MS. So, very helpful for a diagnosis in certain settings. But there's all these practical limitations that have really limited its widespread use.
Dr Albin: That is a beautiful summary. So, it sounds like once we kind of get up to speed in terms of like the protocols for this, having the magnet strength for this, this will be really a game changer in terms of increasing the specificity and also maybe finding things that impact patient's clinical presentation and therefore quite meaningful. But it sounds like for most of us, this is probably not something that they're going to be adopting right away. Is that a fair assessment?
Dr Oh: Yes. And you know, they were included in the last diagnostic criteria revisions. And it really hasn't changed things very much, only because of these difficulties with, you know, requiring higher field magnet strengths and these specialized sequences and then needing training to kind of figure out how you can adequately detect cortical lesions.
Dr Albin: Totally. So, the other thing we've heard a lot about, and I have to say, I was in the AAN fall conference not too long ago, and this came up quite a bit, was the central vein sign and the fascination with that, because it tells us a lot about the MS pathophysiology and again, increasing that specificity. And it seems like maybe this is one that we can more easily adopt in clinical practice. So, tell our listeners about what that is, how they detect it. How many do you need to find?
Dr Oh: Sure. And so, this is one of the imaging measures I'm really excited about. So, the central vein sign heard about it recently. And probably in the last ten years particularly in the MS field we're talking about it all the time. But just wanted to emphasize that the central vein sign is not something that is new. Even back in the 1800s, when Charcot described MS lesions in these ancient textbooks, he actually very clearly described that MS lesions form around the central vein. And that makes sense, because we know that these waves of peripherally mediated inflammation somehow get through the blood-brain barrier and cause this cascade of events leading to inflammation in the brain and spinal cord, which is what MS is. But we know that B cells in T cells require veins to get into the central nervous system. And so, it's no surprise, really, that MS lesions form around veins. And so, this is something that's been known pathologically. But the reason we're so excited about it now is because we actually have good enough iron-sensitive MRI sequences that allow us to see a central vein when it is present within a white matter lesion. As a neurologist, we know that there's probably hundreds and hundreds of different things that can cause white matter lesions in the brain. But when you use an appropriate iron-sensitive sequence and you see that many of them, if not most of them, actually have visible central veins, that tells you that this person very likely has MS. And so that's why we're so excited about it, because there have been many studies done in the last ten years. In fact, so much evidence generated in the last ten years that there have been I think it's now four systematic reviews and meta analyzes. Looking at the diagnostic properties of the central vein sign. And, you know, it turns out that when you look at people with MS, most of them have a pretty high proportion of white matter lesions that have visible central veins. And there's a lot of questions about, you know, how to best use the central vein sign. But when 40% or more of the white matter lesions that you see have visible central veins, then the likelihood of a diagnosis of MS is very high. So, this is why we're so excited about it in the MS field because it's a really useful diagnostic tool. You know, again when you have appropriate ion sensitive sequences, if you see someone with white matter lesions and you see that 40% or more of them have visible central veins, this tells you that this person very likely has MS.
Dr Albin: So, Dr Oh, I hear you say, you know, 40% of the lesions. Does that mean the neuro radiologist needs to look at every single lesion and then count how many have the central veins, or is there an easier way to do this?
Dr Oh: Great question. Casey, there is definitely an easier way because our neuro radiologists would not be our friends anymore if we made them look at every white matter lesion and make sure that 40% of them had the central vein sign. So, because it's so time-consuming to use that 40% threshold, there's an easier criterion that has actually made it into the diagnostic criteria. And it's called Select Six. And what this means is when you have more than ten lesions, as long as you show that six of them have a visible central vein, you just have to count six with the central vein. Then you're done. So that means you're Select Six positive or central veins nine positive. However, if you have ten or fewer lesions, as long as you show that more than 50% of them show a visible central vein, then you are select six positive, and then you're done. So, as you can see, it's a much simpler criterion to apply, and it seems to perform almost as well as that 40% threshold, which is why that is the criterion that's made it into the new diagnostic criteria.
Dr Albin: Perfect. I love that we definitely do not want to make enemies with our neuro radiology colleagues, but yet they do so much for us. So perfect. I'm glad that we can, make their jobs a little easier without losing any specificity there, or just losing a touch of specificity there. All right. If I am working with a, you know, in a center that maybe doesn't do this all the time, am I just getting a run of the mill SWI sequence? Do I need to ask my radiologist for a special sequence? Or is this just, you know, you can get it from the typical array of what our patients are getting.
Dr Oh: You know, SWI is a widely available commercial sequence that's iron-sensitive, the ones that are typically commercially available, they can detect central veins, but there actually are little tweaks that you can do to make it a little more optimal. With the recent diagnostic criteria publication, which was, led by Xavier Montalban and recently published in Lancet Neurology. There's actually a companion MRI paper that was led by Frederick Barkov and Danny Wright. And the reason I'm specifically citing those papers is in that companion MRI paper, there's a table that has kind of optimal sequence parameters that you can use even with a conventional SWI sequence, to try to best detect the central vein sign. And then there's a wide range of different iron-sensitive sequences, and SWI is one of them, but the one that seems to have emerged as most sensitive to detect the central vein sign is something called the 3D T2*-EPI sequence. But the bottom line is there's a whole bunch of different iron-sensitive sequences that you can use, little tweaks that you can do to make them optimal, to be able to visualize central veins when they're present within white matter lesions.
Dr Albin: Incredible. So like partner with your neuro radiologist, there is a great sounds like a field guide almost to this. So, it makes it easy to pick up in your standard of care so that you can make sure that you are detecting them at the optimal level to see that more specific diagnostic biomarker.
Dr Oh: Yes. And you know, in contrast to what we were talking about with cortical lesions, you can actually detect central veins when you use these iron-sensitive sequences at any field magnet. So even at 1.5 Tesla, particularly when you use contrast, which is often given with the diagnostic scan anyway, you can very easily detect a central vein. So that's a huge benefit because it allows for widespread use. As long as you work with your radiologist to get the right iron-sensitive sequences in.
Dr Albin: Yeah, that's incredible. I mean, I think that it really will be practice-changing. And then the last one that I think was honestly new to me, I feel like I had heard a lot about the central vein sign, but the whole new to me term was this paramagnetic rim lesion. So, what does that tell us about the underlying biology of MS? And are there any other things that might also have this finding that we should sort of be aware of? And how specific is it?
Dr Oh: You know, the central vein sign is kind of the main, really new imaging measure that's made it into every part of the MS diagnostic criteria. And then together with that paramagnetic rim lesions or we call them PRL or pearls for short, they've made it as well, but in a much more limited way only because there's not as much evidence that has accumulated over time to support the diagnostic utility of pearls. But first of all, what are pearls? So, people in the MS field are really excited about pearls, because we know that they capture a subset of what we call chronic active lesions. So, MS lesions will form acutely and over time, some of them will become inactive. And then some of them are chronic active lesions, meaning that they have this rim of activated microglia around them. Over time, they continue to slowly expand. And it's almost like this slow burn. And the reason why we focus a lot on chronic active lesions is because we know that they're a driver of progressive disease biology and MS, meaning that in people who have progressive MS or who have pretty severe disability, global disability or cognitive disability, we know that they have a high burden of pearls. And so that's why there's so much excitement in MS about being able to image chronic active lesions. It's because we're always looking for an imaging measure that allows us to accurately predict progression or to, measure progression over time. So that's why there's so much excitement in MS about pearls. But as kind of an added bonus, it turns out pearls are also really specific for MS. And so, when you use the same iron-sensitive sequences, by the way, that's used to detect the central vein sign when you use appropriate iron‑sensitive sequence. And if you see that someone has a pearl, the likelihood of a diagnosis of MS is very high. The one exception to that is Susac syndrome, where pearls have been observed. But other than that, with many other white matter diseases like neuro rheumatology disease, NMOSD, MOGAD, you really don't see pearls. And so, this is why it's made it into the new diagnostic criteria. In contrast to the central vein sign, though, not everybody with MS has a pearl, so the sensitivity isn't as high. However, it's really, really specific in the range of, you know, 90 to 95%. So, this is why it's been added as, an imaging measure in certain settings. It can help facilitate a diagnosis. But the real utility, again, is when you use it, it helps you to prevent misdiagnosis.
Dr Albin: It's fantastic. And hearing you talk about that, this one stands out to me as a biomarker that not only helps increase our diagnostic specificity, but also may really inform if the patient has having progression despite the treatment they're on, that this could play a role in helping you say, look, there probably is something that we need to switch because we can still see this ongoing progression.
Dr Oh: Yes. And especially in this new era of treatment in MS. I think, you know, MS as a field, we've been so fortunate to have so many treatments emerge over the years that mainly target relapsing disease. But we hopefully, in the next little while, in short order, I hope we'll have treatments that target these progressive disease biologies. And so, not only is it helpful as a diagnostic marker, but there's a lot of evidence accumulating, showing that it may have a lot of prognostic value and will also help guide treatment decisions, exactly as you said.
Dr Albin: It truly does sound like it's a great time to be an MS doctor there. So, so many new advances in the field. There is so much more that we can do for these patients in our limited time left. I'd love to ask you, what is it that you're most excited about now with the change in the biomarkers, the change in the treatment, what makes you really excited to be a doctor specializing in MS right now?
Dr Oh: I feel like we're on the brink of a new era of treatment. I think, you know, in the last two decades, MS care has changed so dramatically. I remember, you know, way back when, as a medical student, when I did my first neurology elective, this was when the first treatments for MS were emerging. And the prognosis that we were talking to patients about at that time is like night and day compared to what we talk to them about now. But we're going to do even better in the next couple of years. And so, there's a number of new treatments that hopefully will be approved soon that, for the first time, have shown an effect in clinical trials where it seems to be decreasing progression that is independent of relapsing activity. And that's really the greatest unmet treatment need that we have. And it seems like we might have some therapies on the horizon that can actually target that aspect of progression. It's really exciting, and even more that we're going to be able to do for our patients to completely change the way, we look at and the way we treat MS in the years to come.
Dr Albin: Dr Oh, this has just been fantastic. To all of our listeners, I really want to point you to the article because obviously, as an imaging biomarker article, there are so many beautiful images. There are great examples. There are some fantastic cases that show how applying these new biomarkers can help get you to the right diagnosis. This is truly a tour de force of how imaging has really shifted the care that we provide patients with MS, and so please go and check it out. It is one that you do not want to miss. And again, today I've been interviewing Dr Jiwon Oh about her article on diagnostic neuroimaging biomarkers for multiple sclerosis, which appears in the April 2026 Continuum issue on multiple sclerosis. Thank you again, Dr Oh, this has just been such a delight.
Dr Oh: Thank you for having me on the show, Casey, and look forward to people reading the article.
Dr Monteith: This is Dr Teshamae Monteith, associate editor of Continuum Audio. If you've enjoyed this episode, you'll love the journal, which is full of in-depth and clinically relevant information important for neurology practitioners. Use the link in the episode notes to learn more and subscribe. AAN members, you can get CME for listening to this interview by completing the evaluation at continpub.com/audioCME. Thank you for listening to Continuum Audio.
