Applications of 7T in the Care Continuum – From Research to Clinical Care

Podcast Transcript

Intro: Neuro Pathways, a Cleveland Clinic podcast, exploring the latest research discoveries and clinical advances in the fields of neurology, neurosurgery, neuro rehab, and psychiatry.

Glen Stevens, DO, PhD: Although 7-Tesla MRI was first approved by the FDA for clinical diagnostic use in October 2017, Cleveland Clinic began using its 7T MRI research system for research purposes, as early as 2014. 7T field strength offers increased signal to noise, and contrast to noise ratios, resulting in sharper images, with potentially better detection and visualization of cortical malformations.

In today's episode of Neuro Pathways, we'll discuss the applications of 7T in the care continuum from research, to clinical care. I'm your host, Glen Stevens, neurologist, neuro-oncologist in Cleveland Clinic's Neurologic Institute. I'm very pleased to have Dr. Stephen Jones join me for today's conversation. Dr. Jones is Vice-chair for Research and Academic Affairs in Cleveland Clinic's Imaging Institute, and Staff Neuroradiologist in Cleveland Clinic's Neurologic Institute. Stephen, welcome to Neuro Pathways.

Stephen Jones, MD, PhD: Thank you for having me. I'm looking forward to this.

Glen Stevens, DO, PhD: So for our first question, in the last decade, several technical improvements have led to strengthening the magnetic field of MRI, to produce higher resolution images. The outcome is the introduction of ultra-high field 7T MRI scanners that have many advantages in comparison to the routine MRIs, such as 3T MRI. Can you start our conversation by taking us through the advantages and drawbacks of 7T?

Stephen Jones, MD, PhD: Let me just begin that by talking about in general, what about the 3-Tesla? This magical machine, MRI, that has this ability to look inside tissues without having to use a scalpel, we take for granted, and it all comes from looking at the signals that come from the water molecules that are inside of our head, and the more magnetic field we have, the stronger those signals we get, and engineers love signal, and the more we have, we can do things with it. In particular, we can look at smaller voxels. I like to think of 7-Tesla in an analogy with television, as high definition MRI. We take it for granted now, if you look at televisions, the cathode-ray tube that we used to have, and the fuzzy pictures, they'd be unacceptable today, and when we came out now with high definition TV, which is now in every home, that's the standard quality of crisp pictures, tiny pixels that we can see.

So I like to think of 7-Tesla as an analogy like that. We're going from three up to seven, we get all this extra signal, and then it's money in the bank that we can use, and we spend this signal typically to get smaller voxels. There are a few other advantages we might have, tissue characteristics might look a little different one way or the other, it's more sensitive to blood products. Then in the functional MRI, which is just a very interesting phenomena that we can look at, improves also with 7-Tesla. So there are numbers of advantages.

Some of the disadvantages are that all MRI has some distortions, some artifacts, and these also unfortunately get amplified at 7-Tesla. But if we look at the arc of discovery and development of MRI itself, every time we've gone from a lower field to a higher field MRI, there have been problems at first, but once these clever engineers have produced thousands of these machines, many of these disadvantages are addressed and taken care of. So I would think that in the decades to come, we're going to find the drawbacks currently at 7-Tesla, will no longer be there. So I'm excited for the future with 7-Tesla imaging.

Glen Stevens, DO, PhD: So just on that point that you raised, can we go higher? Have we gone higher? Is there higher than 7T?

Stephen Jones, MD, PhD: There's some very exciting experiments that are being done in France, and some here in the United States where yes, they've been able to push it above 10-Tesla, I think approaching 11-Tesla, and there's one that's almost 14-Tesla. You start developing different categories of engineering difficulties at those sorts of levels, there are some talks of getting up to 20-Tesla, and I even saw one talk that fantasized getting up to 80-Tesla, but every time you make those steps, completely new problems start to come up.

Glen Stevens, DO, PhD: So I'd be concerned about my fillings, but we'll leave that for another time. So the 7T is used for a broad range of applications across clinical subspecialties. Can you share examples of research and clinical applications your team is using the technology for, in the fields of neurology and neurosurgery? And I know on a personal level, you and I have worked with a couple of brain tumor patients to try and help in the differential diagnosis.

Stephen Jones, MD, PhD: Sure. There are many different diseases, but let's start with what you just mentioned, brain tumors, is that the 7-Tesla will be able to give us better detail where it's needed on some of these tumors. I think I remember with one of our neurosurgery colleagues, maybe a couple of years ago, there was a lesion near the base of the brain, and it's very important, as you know, is this a tumor that's inside the brain, or just outside the brain pushing in? And trying to get the tiny details matter, and the lower field strength MRIs that we had, we couldn't quite be sure, we came to 7-Tesla and then we could say, "Ah, this is a tumor outside the brain. This is probably in this category, and we will treat it thusly." So that was one that came to mind.

I think others are, it's seeing the texture of some of these tumors, and this is work that is going on throughout many 7-Tesla machines throughout the world, is if you can look with high definition MRI, can you see texture of tumors a little bit better, and does that texture tell you something about the native tumor behavior? If we go to the field of epilepsy, which I have done most of my work in, this is also one where detail can matter. Sometimes we're looking for these tiny little lesions that are in someone's brain on the cortex, for example, and as a physician-scientist, this a very exciting field to work in because epilepsy patients, as you know, are typically younger patients. This impacts a long life of someone that's going to be on strong medications, cannot drive, troubles with jobs and relationships, and if you can just find a little lesion in the brain and you can have a surgeon excise it, you may buy someone a lifelong seizure freedom, and that's a tremendous thing.

So how could 7-Tesla come into this? This may come into play by finding small lesions that we can't quite pick up at smaller field. Again, high definition MRI, being able to see something we couldn't quite appreciate before.

Glen Stevens, DO, PhD: Steve, any comments about traumatic brain injury in 7T?

Stephen Jones, MD, PhD: Unfortunately, most mild traumatic brain injury shows normal MRIs. Now, we know the patients are suffering. We know that something is there that's wrong in the microstructure of the brain, but often, MRIs just can't quite see it, and sometimes you can see tiny little hemorrhages that might've occurred. Now, 7-Tesla, it is exquisitely sensitive to the chronic blood products that might come from little microhemorrhages. So we have seen many patients that might have questionable TBI, and we can use the 7-Tesla as this microscope for small hemorrhages, and we can see where they might be and change the diagnosis for traumatic brain injury.

Glen Stevens, DO, PhD: And lastly, in terms of things to treat, what about degenerative brain disorders? How is it helpful there?

Stephen Jones, MD, PhD: So one of the interesting applications for degenerative brain disorders is related to the microhemorrhages. For example, there's a close association in Alzheimer's disease with amyloid deposition, and amyloid deposition may also occur in areas surrounding blood vessels that make them more likely to bleed. So we've just discussed how 7-Tesla MRI is more sensitive to hemorrhagic products, and what we can see in some people that have this disease, amyloid angiopathy, is exquisite numbers of microhemorrhages that have a cortically based distribution, very characteristic, and 7-Tesla can just nail that because it can show you the numerous microhemorrhages in this cortical or gyriform pattern, and can help nail that diagnosis.

Glen Stevens, DO, PhD: And I'm curious as to whether or not magnetic resonance angiography is improved with 7T, or is three fine?

Stephen Jones, MD, PhD: So again, it's about more signal and with more signal, if you want to, you can make smaller voxels or smaller pixels, and indeed, the MR angiography that we can make, can be almost as good as catheter angiography. So this is worth the remark, catheter angiography is the gold standard for being able to diagnose small vascular lesions in the brain. It also has the added advantage of not only diagnosing, but you can treat, is the skilled neurosurgeons and neuroradiologists are able to thread catheters from the groin up into the middle of the brain, and sometimes treat these lesions, but there's always a small possibility that when you have catheters doing this intervention, of causing small strokes.

So if all you want to do is diagnose, you just want an image, does some small lesion exist or not, it is wonderful that you could have 7-Tesla MR angiography almost the equivalent of catheter angiography. So you wouldn't need to take the risk of giving someone small strokes, simply just to diagnose. We have found several examples of aneurysms that might be in the middle cerebral arteries near the ophthalmic artery origin, and that's a very important location, because is the aneurysm intradural or extradural? And sometimes it's very difficult to see that on low-field MRA, but 7-Tesla MRA, those extra small voxels can help you make that diagnosis.

Glen Stevens, DO, PhD: So I really appreciate your case examples. Any other complex cases that you've seen over the years, that 7T has helped make a differential diagnosis or treatment decision for?

Stephen Jones, MD, PhD: We had one very interesting case. This was a patient who came to the clinic, a middle-aged woman, and her husband was a taxidermist, and she started having mental status changes, and her brain MRI was inconclusive. And we thought maybe that there were multiple small lesions, and did these small lesions have a little focus of calcium on them, or susceptibility effect or not? Now, anyone who knows infectious diseases in the brain is going to immediately say, "Could this be cysticercosis?" So we went to 7-Tesla, and we looked and we saw in the extra detail, sure enough, the characteristic ring sign of cysticercosis.

So there's an interesting caveat to the story, is that she also had other lesions in the liver and they were able to biopsy some of them, and it wasn't cysticercosis. They weren't sure what it was. It was sent to NIH, and they did an analysis, and it turned out to be a cousin of cysticercosis, Versteria, and Versteria is a zoonotic version of cysticercosis. In other words, lives in animals. So this is one of the first known transmissions of Versteria into humans, and it was maybe related to the fact that her husband was a taxidermist. We don't know for sure. But I thought this was so interesting that because of 7-Tesla, we made this interesting diagnosis.

Glen Stevens, DO, PhD: Well, I have to tell you, you really got me excited about 7T here with these stories, it's great. Where might we take 7T that we haven't been yet?

Stephen Jones, MD, PhD: I think an exciting one, which would be related to your work, would be to look for micrometastasis. So, you know when you have patients that have metastasis, they will appear often as small little lesions that might only be a few millimeters big, and with lower field MRI, we look for the enhancing small lesions, as you know, we do this every day. Wouldn't it be good if you had high definition MRI that was able to see these things at a smaller and earlier stage, and would this benefit the patient, that we'd be able to treat these micrometastasis at an earlier? And I think this is work that I know is now being started at other institutions, and we hope to embark on this ourselves.

Another area where we can use 7-Tesla is in multiple sclerosis, MS. And while we see many patients whose brain MRIs with multiple sclerosis are very characteristic and we can just say, "Yes, this is like multiple sclerosis," there are many patients that are in a gray zone, and they may have small little lesions in areas of the brain that are ambiguous. We just don't know if it's simply MS, or maybe they are non-specific things, and what I might call age spots in the brain that as you get older, they just accumulate, and trying to distinguish between those two can be problematic.

Well, with 7-Tesla, we can see a feature of multiple sclerosis lesions that's very small, and helps to identify this as a true multiple sclerosis plaque, and that is the central vein. That is, that the multiple sclerosis lesions tend to form in a cylinder around a segment of vein, and these are only about one millimeter or so big, and the lesions start from that. So what 7-Tesla allows us to do, is we look for the central vein, and these tiny little lesions. We look for a little dot in the center of this little white spot, and that's characteristic multiple sclerosis.

Another exciting thing is targeting for deep brain stimulation, or DBS. Here, our skilled neurosurgeons have this fantastic technique where they can put electrodes inside the brain, within millimeters of accuracy. It's still, I don't know how they do it, and I'm in awe of this skill, but they have to know where to go, where to put these electrodes in order to have an effect. Now, one that we do is for essential tremor, or in Parkinson's, where you can have patients with debilitating shaking of their hands. They can't sign a checkbook, they can't use their iPhone, they can't hold a glass of water. But if we can find the tiny little lesion in the thalamus, for example, and make a small little lesion that's only about three or four millimeters big, that tremor can go away, but the key is, we've got to find that location.

And so, an exciting thing for 7-Tesla is to use some of it slightly different and improved high resolution look at the brain, that can help directly visualize some of these foci. And in addition, we can start combining this with other interesting aspects of MRI, the functional MRI of the brain. We can look for brain connectivity, resting state connectivity, diffusion tensor connectivity, and we can try to see on an individual patient basis, how we can see these locations, how we can help our surgeons target. And our HIFU, high-intensity focused ultrasound, is another very exciting science fiction-like technology we have where we can do brain surgery without a scalpel, and we can use focused ultrasound in an MRI setting, and we can focus and heat up that spot in the thalamus. Again, it all comes back to where to target, because we can steer these spots very carefully, and we're excited to use 7-Tesla, combined with HIFU, to improve patient care.

Glen Stevens, DO, PhD: Excellent. So before we sound off, are there any additional takeaways that you have for providers like myself, specific to 7T MRI and its use in medical practice?

Stephen Jones, MD, PhD: I think the best way to view this machine, which is a very expensive machine, as we could all imagine, is that it's a problem solving instrument. In other words, if you have a patient and you want to image them, I would not recommend 7-Tesla to be the first line of scanning that you would do. We find the use is that you would do a regular, say, 3-Tesla, and when you still have problems that you don't quite know what's going on, and you want to be able to get a better look, a better definition, 7-Tesla becomes your problem solver. In one sense, I'm not sure whether every hospital has to have multiple 7-Teslas, but every catchment area probably should have one.

I make an analogy, if I go back to television, remember looking at a football game or a baseball game with old cathode-ray tubes, and if you saw the score in the bottom corner, remember how we might use to squint, and we tried to see, "Is that five to three?" We could still enjoy the game, but sometimes detail matters. Now, with this high definition MRI, you don't have to squint, you can see it right there.

Glen Stevens, DO, PhD: Very well said. Well, Stephen, thank you so much for joining me today. I really appreciate your time and insights, and I know I learned a lot today, so thank you very much.

Stephen Jones, MD, PhD: Well, thank you for having me. I really enjoyed this.

Outro: This concludes this episode of Neuro Pathways. You can find additional podcast episodes on our website, ClevelandClinic.org/neuropodcast or subscribe to the podcast on iTunes, Google Play, Spotify, or wherever you get your podcasts. And don't forget you can access real-time updates from experts in Cleveland Clinic's Neurological Institute on our consult QD website. That's consultqd.clevelandclinic.org/neuro or follow us on Twitter @CleClinicMD, all one word and thank you for listening.