How to assess a left ventricular thrombus with the help of cardiac MRI (CMR)

Assessing a left ventricular thrombus with echo can be a tricky thing. CMR can come in handy in these situations. In this video, cardiac imaging specialist Andrew Houghton, MD will explain how to use CMR when a left ventricular thrombus is suspected. Also, you’ll learn how to differentiate a left ventricular thrombus from cardiac tumors, and much more.

Targeted towards internists, cardiologists, and radiologists in training, this course teaches you everything you need to know about cardiac MRI (CMR) from a clinical perspective. You'll learn when to order it and how to assess common conditions, including myocardial ischemia, infarction and viability, common cardiomyopathies, valvular stenosis, regurgitation, and common congenital defects.

[00:00:00] In this lesson, we're going to learn how to assess left ventricular thrombus, using CMR. If you're familiar with echocardiography then you'll know that it's commonly used to assess patients for left ventricular thrombus but with variable reliability. CMR offers high-resolution imaging without many of the limitations of echo such as suboptimal imaging windows. Late gadolinium-enhancement

[00:00:30] CMR is particularly valuable as left ventricular thrombus is avascular. This means that the gadolinium contrast is absent and areas of thrombus appear very dark. This means that they stand out quite clearly against the adjacent myocardium, particularly when the adjacent myocardium is infarcted and therefore, contains bright gadolinium enhancement. Late gadolinium-enhancement CMR detects left ventricular

[00:01:00] thrombus in 7% of patients who have left ventricular systolic dysfunction. This is a cine-CMR image showing a four-chamber view. And this is from a 47-year-old man with an ischemic cardiomyopathy. He has an overall left ventricular ejection fraction of 36%, as a result of a significant area of myocardial infarction affecting the left ventricular apex. This is the left ventricle

[00:01:30] and we can see that the apex is dyskinetic, it pushes outwards during systole. As a consequence of this area of akinesia, a large laminated thrombus has built up at the apex and we can see this on the cine-CMR image. This is the same patient with an ischemic cardiomyopathy. This is a cine-CMR taken in the two-chamber view. We have the left ventricle, here,

[00:02:00] the mitral valve, and the left atrium. And once again, we can see that the left ventricular apex has been affected by myocardial infarction. It's dyskinetic and there is this large laminated apical thrombus present at the apex. These are also images from the same patient. These are late gadolinium-enhancement images. So, these are taken ten minutes after the administration

[00:02:30] of intravenous gadolinium contrast. Because the patient is having an apical infarct, there is late gadolinium enhancement present at the left ventricular apex. This is a four-chamber view and the left ventricle is here and we can see the left ventricular apex contains subendocardial and towards the apex itself, virtually full thickness, late gadolinium enhancement. This is a two-chamber view,

[00:03:00] left ventricle and left atrium. And again, there is late gadolinium enhancement, virtually full thickness, throughout much of the apex. The thrombus can be seen much more clearly on these images than on the previous cine-images and that's because thrombus is avascular, and that makes it dark. It doesn't take up any gadolinium contrast. And so, on these two images, we can see this dark irregular

[00:03:30] structure at the apex surrounded by the infarcted myocardium, which is very bright because of the presence of late gadolinium enhancement. And so, late gadolinium-enhancement CMR is the most sensitive technique for helping to identify the presence of left ventricular thrombus. So, let's take a look at a different patient. This is a 68-year-old man who has also had an apical myocardial

[00:04:00] infarction, causing a ischemic cardiomyopathy. His left ventricular ejection fraction is 37%. And we can see that the left ventricular apex is a little dyskinetic. It pushes out just a little during systole, which clearly provides a substrate to develop a thrombus. But is there an apical thrombus present? Well, it's a little hard to say in this view. There's a little abnormality, here but it's

[00:04:30] hard to say for certain whether that represents a thrombus or not. So, let's take a look at the late gadolinium-enhancement image. And here it is, this is the same patient. This their four-chamber late gadolinium-enhancement image. And looking at the apex, it's not really evident that there was any thrombus there. But this case has been chosen to illustrate the importance of having to look at the left ventricle in multiple

[00:05:00] different views. So, let's move on and have a look at this patient's two-chamber view. So, here's the same patient. This is their two-chamber cine-CMR image. And here's the left ventricle, mitral valve, and left atrium. And here's the left ventricular apex and this time, I'm much more suspicious. Looking at the apex there's this area in the apex just sitting here, which looks very

[00:05:30] suspicious of an apical thrombus. But to try and prove this, let's again take a look at the equivalent late gadolinium-enhancement image. And here it is, this is the late gadolinium-enhancement image and now we can clearly see an area of myocardial infarction with late gadolinium enhancement at the apex. And sitting within that, in the cavity of the left ventricle is this dark avascular area,

[00:06:00] which represents a left ventricular apical thrombus. So, this wasn't at all clearly evident in the four-chamber view, even on the four-chamber late gadolinium-enhancement view but is clearly evident in the two-chamber view. So, the lesson from this case is the importance of taking multiple views, four-chamber, three-chamber, and two-chamber views of the left ventricle to look carefully for any evidence of thrombus.

[00:06:30] So, in summary, how do we perform CMR for left ventricular thrombus? Well, we should always look carefully for left ventricular thrombus in patients with left ventricular systolic dysfunction particularly in those with an ischemic cardiomyopathy because these are the patients that run the highest risk of thrombus formation. We need to carefully inspect cine-CMR images for anatomical evidence of thrombus and we need to do so in multiple different

[00:07:00] views. But the best sensitivity is with late gadolinium-enhancement CMR images. Thrombus is avascular and so contrast uptake is absent. This means that thrombus appears very dark on a background of myocardial infarction, which appears very bright. If you'd like to read more about the use of CMR to detect left ventricular thrombus, take a look at this paper published in the Journal

[00:07:30] of the American College of Cardiology. Now, that you've seen some examples of left ventricular thrombus using CMR, let's put your skills to the test with some quiz questions.