Chapters Transcript Video Advances in Cardiac MRI Dr. Edward Sawey reviews the physics involved in cardiac MRI and associated case studies. Hey, good morning. Um So, uh uh you know, we were the name was uh advances in cardiac MRI but um we don't um sometimes I think understand completely the indications currently. Um But I am probably gonna go over more than you really ever wanted to know. Um And so advance the slide. Which one here? Oh, ok. The green one. So uh I don't have a disclosure slide, but I don't have any disclosures. What we're gonna be doing is going over physics. You guys are super excited about that. I know that um some common indications uh for cardiac MRI, um some case vignettes. Uh and then there'll be some room for questions at the end. Uh particularly if you want to discuss the physics, we'll, we'll just go all through all of that in deep detail. Um So here is the cardiac MRI scanner. Um You've seen this before. Uh But what, what I would like to point out is um some things that where's my laser there? It is, it's kind of weak, there are uh uh coils that um go over the chest. Um And you don't really, maybe most of the population doesn't realize that those are those absorb the actual image data. Um you know, and then you see the MRI machine which is uh the huge magnet and I have a laser pointer that's dying. Um So, um we'll go on next. And what exactly is this MRI machine? Um It, it's, it's a huge magnet. I mean, just really straightforward. Um if you've ever, um you know, gone to physics class and, um you know, wrapped around uh a wire. Oh, thank you across um across like a pencil or something like that, you know, and like maybe fifth or sixth grade, you put a battery on there and it's a magnet. This is exactly what it is except it's a super magnet. So what we have here is the cardiac MRI and you have superconducting coils in here and there's liquid helium in there. And I, um I was wondering exactly um you know how cold is liquid helium because you have vacuum insulation. So you have insulation in here to protect the rest of us from how cold it is. Um the liquid helium is negative 452 degrees. That is um it's a little cold. Um So um the, the reason for that is it allows the fast acceleration of electricity through there in order to generate this very, very strong magnetic field. So you've heard this, it's 1.5 T MRI. What is 1.5 T anyways, what's three T seven T we have 1.5 T this is generally the standard across the country. Um 1.5 tesla is 30,000 times stronger than the magnetic strength of the earth. So, whatever we're expanding, you know, feeling here, if you've ever had your good old compass pointing to the north, it's about 30 times stronger than this. And this is the basis for how cardiac MRI works or any MRI for that matter. So what happens is in your body right now, you have a bunch of protons. Um And I'm sure you know that, but you cognitively probably know how to wear and they're oriented in space and they're pointing up down sideways, they're spinning left, they're spinning, right, really. And truly, they're just doing whatever they want to do, just being left alone. You put them inside the magnet and they all orient up, they start spinning in the same way and they start pointing in the same direction. Now, this is important. Um You know, don't pay this a little bit too much over here. What we do is we hit the body. Um And that sounds a little violent. Um But if we give the body a pulse of radio frequency and it knocks all of these protons off of their access and then as they come back on their access, it's called procession, they release photons and those photons are then recorded by the cardiac MRI. Um Now you may have wondered why can't, I bring my cell phone into the cardiac MRI, I don't think it's gonna fly in there. We've all seen the pictures of, um, you know, stretchers going into the MRI machine that may not happen with your cell phone. But what is your cell phone generate radio frequency? Um, if you, if you weren't aware inside of that area, you're inside of something called a Faraday cage, there are no radio frequencies that can come in or go out of that room right now. We're bathed in radio frequencies. I don't mean to scare all of you. Um But um there are no radio frequencies that can get in there because we don't want any of this uh kind of muddying up our pictures. So what comes out is, well, you would like to think that this is what comes out initially, but this is actually what comes out, it's called the case space. Um I don't really understand it. I'm gonna be honest, I know I do this but um it comes out and this is all of the detection of, of what the MRI sees and it's transformed into pictures of the heart using something called um the four a transformation. I know you guys are all super excited about this. So I really looked it up and I pulled up how exactly it happens. You did just go through a few of these kind of, you know, very common uh mathematical equations, you know, and uh we're just not gonna go through that. So, um what are common indications for cardiac MRI uh viability and coronary artery disease. Um So you have clued coronary arteries, you want to know, is there a bunch of scar there or not? Is there my cardi that's alive that if you open up blood vessels, you're gonna perfuse. If you perfuse scar, it's not gonna contract any better uh evaluation of structure. Um You know, we have a lot of evaluation of structure from our cardiac CT. Uh we have congenital uh MRI S to evaluate structure. You can evaluate the pulmonary veins, pulmonary arteries, any particular portion of the heart that you would like rule out. LVRV, thrombus. Uh this becomes a big one. You know, a lot of times we're wondering, you know, oh I see this kind of little thing flying around in the apex is that, you know, is that a thrombus? And then you start committing somebody to possibly lifelong anticoagulation. That's not without risk, right? They could bleed, they could fall about their head and get a, get a subdural hematoma. You don't want that. So sometimes if it's unclear, you rule out thrombus uh evaluation for infiltrative disease, amyloidosis, sarcosis, mark, uh myocarditis, um amyloidosis, you'll hear a lot about later. Sarcosis can affect anywhere in the body, but it's particularly important in the heart as it can stop your heart from conducting electricity. Um And you like your heart to conduct electricity so it can keep eating. Uh myocarditis um sometimes is not a life threatening issue though it can be a highly life threatening issue. Hypertrophic cardiom fibrosis is very important and it's become important. Over the years, we focus traditionally on size and the degree of obstruction over the LVOT. But today, we also consider how much fibrosis there is inside the myocardium. If you have 15% or more fibrosis, as analyzed by delayed gadolinium enhancement, you are at higher risk for sudden cardiac death. And these people are considered for IC DS much more frequently. Pericardial evaluation. Patient comes in with chest pain, you know, normal coronaries and you're like, what's going on. I don't understand what's going on. You can evaluate for pericarditis or they're having shortness of breath, but their ef is normal and the echo is particularly unrevealing. Maybe the septum bounce is a little funny. You can evaluate for pericardial constriction scar evaluations. Uh People with uh you know, ventricular arrhythmia sometimes uh you can point the electrophysiologists in a proper direction and say, hey, you know, in the middle of uh the near the attachment of the RV, their scar and, you know, kind of take a look over there, maybe that's the area that your ventricular tacho cardia is coming from and cardiac masses we're not gonna be going over. Uh but very powerful method for characterizing the tissue of cardiac masses. Uh and exactly what type of cardiac mass it is and whether or not you need to have open heart surgery or not, it's kind of a big decision you don't want to go in just because you saw something a little funny. So you'd like to know what it is before having uh one of our wonderful cardiac surgeons take a look. So, case number one, it's gonna be a lot of images here. Male, 70 year old, male chest pain and stemi acute decompensated heart failure with uh medical history of aortic aneurysm diabetes incurred. And he has no previous history of coronary artery disease, but he has a troponin that's fairly impressive. Um He has an geography and what you see here is uh the left main, that's the left anterior descending artery, but this right here um that's blocked if you don't know coronary angio angiograms, I don't think you really need to. That's the circumplex artery that's completely blocked, that was not able to be vascularized. And of course, they looked at the other side and the other side looked fairly ok. A little bit of tightness but fairly. Ok. So what happened? Medical management, no intervention. The left circumplex was a complete and total inclusion. Uh medical management with dual anti platelet therapy. Um you know, aspirin ta and beta blocker and ace and the patient was sent home comes back two weeks later and he's having acute decompensated heart failure. He has a right heart catheterization and I think the thing to really pay attention to here is the wedge pressure is 38. He actually has normal uh normal. You know, the right pressure of five is his fluid volume is pretty OK. But the left side of pressure is extraordinarily high. So of course, echocardiogram and this is what you find. So what you're looking at here, the right side of the heart is pumping. Well, the left side, I mean, that doesn't look like a usual kind of cone shape, right? What's going on over here? There's uh little bulging, it's not exactly clear. Uh You get definity because you want to get a little better picture of it. And what you're seeing here uh is a little bit of bulging on that side. Um It looks aneurysmal. So in the setting of acute decompensated heart failure with ef with severe wall motion abnormalities, the thought was, well, we know the circumplex is blocked. Um It correlates with that area. Um Can we do anything if opening it will fix this? So we get a cardiac MRI and here's what cardiac MRI looks like. And for me, it's really like a HD TV. Uh you know, compared to an echocardiogram and what you see, you see some bulging over here. But when we go to the next image, it's really, really quite profound, you see this aneurysm right here. Um And still, it's a little bit not clear what, what is going on in this uh kind of basal segment over here. So we do the imaging, we get what we call the gadolinium enhancement. And we see scar here, there's enhancement. It's all the way through and through. Um you know, and we see scar here. It's almost all the way through and through. There is no viability in that area that circumplex should not be gone after there's much more risk than benefit. So we go here. Uh oh What is that? That should look like this color, it should look like scar. What what is that? We don't know what that is right away. So we go and investigate it a little further. This is a long inversion time and this ends up being a large burden of clot over there that we did not see on echocardiogram. And without contrast, we really didn't see it entirely on noncontrasted imaging. Um And you can see it here moving. It's right in that aneurysm. It's a large burden of clot. And what happened with this patient? He continued medical management. Oh, sorry. Uh He continued medical management. But um you know, now with Warfarin to prevent him from having a massive stroke from this um from this thrombus. So I'm gonna move through the next case kind of quickly even though it's super interesting. 37 year old male admitted with sepsis and viral illness. He's visiting Virginia, of course, because Virginia is for lovers. Um The primary medical history is not significant. He doesn't have any coronary artery disease. Um, he goes up and his health strips are abnormal. Would you look at that? That looks very much like an inferior stemming? It's a pretty scary looking. So, uh, we call up, uh, doctor, doctor takes him to the, uh, cat lab. No, I don't know if it was doctor or not and here's what we find. It's normal looking red coronary. That's exactly where the infarction should be. Next. We look on the left side, exactly what you would expect from a 37 year old male with no past medical history. All of these coronaries look normal. What is going on here, troponins peak at, you know, almost 6000. So for use of you, those of you that don't know that is really high. Um static, a cardiogram is performed at this time and what we're seeing is, you know, really unusual wall motion. You know, the base is contracting. You're having some unusual wall wall motion over here. Um again, not fitting a corn coronary territory so much. Um It's a little bit more uniform uh in the interior and inferior walls. And you see that the septum is moving fairly well. Uh but the rest of this is not. So the operating diagnosis is forming at myocarditis. He had a viral illness and then he has this extreme heart failure and a myocardial biopsy is obtained a sub endocardial inflammation, focal overlying thrombosis negative for giant cell myocarditis. These findings are not really, they're not really particularly impressive, still kind of on the fence, what exactly is going on here? So cardiac MRI of course, is ordered because this is a cardiac MRI talk and here is your images again. And uh as you see, we're not, we're not fitting a normal coronary territory and I'm running out of time. So I wanna explain exactly how that is. Um But you're seeing that the ef this is 17% again, very low. So we have to delay gadolinium enhancement, the enhancement. That's all myocarditis right there and look at the septum when you biopsy somebody, the septum, the op comes in here and you take a sample from the septum right there and that's where you're trying to get stuff and the biopsy from that area was unimpressive and this is exactly why this is why biopsies are low yield. This, look at this whole thing. That's all myocarditis. That is a tremendous amount of myocarditis. It occupies uh 37% of the myocardium um or 32. Sorry, I exaggerated that a little bit. But um so anyways, uh he was discharged home on steroids and he was referred for advanced heart failure treatment at his home. Um And I hit it just on time. Those are the common indications and if you have any questions, I'm willing to take them going once twice. All right. Thank you so much for your time. Published October 17, 2023 Created by Related Presenters Edward J. Sawey, M.D. Sentara Advanced Heart Failure Center View full profile
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