Assessment of left ventricular size and function are two of the most important areas of CMR. In this video, cardiac imaging expert Andrew Houghton, MD will teach you the nuts and bolts so you can take your skills to the next level.
This video was taken from our CME accredited CMR Essentials course taught by Andrew Houghton, MD–Cardiac imaging specialist and head of cardiac imaging at Grantham & District Hospital.
[00:00:00] In this lesson, we're going to look at the fundamentals of left ventricular assessment using CMR. CMR allows us to assess both left ventricular size and function. We can assess systolic function both regionally using a multi-segment model of the left ventricle and also globally calculating stroke volume and ejection fraction. We can measure left ventricular cavity volume in both
[00:00:30] diastole and systole. And we can assess left ventricular wall thickness, both globally in the case of concentric left ventricular hypertrophy and also regionally in the case of hypertrophic cardiomyopathy. We can quantify left ventricular mass, with an accuracy that is second to none. And we can use late gadolinium- enhancement imaging to identify areas of myocardial infarction or
[00:01:00] fibrosis. When we assess and describe left ventricular regional function in our CMR studies, then we make reference to left ventricular segments. Most CMR centers use either a 16- or 17-segment model to describe the left ventricle. And in this diagram, we have three short-axis views of the left ventricle, on the top of the screen,
[00:01:30] these being the basal, mid, and apical short-axis slices. Basally, we have the mitral valve orifice, represented here. And we have six segments of the left ventricle. We have the anterior, anterolateral, inferolateral, inferior, inferoseptal, and anteroseptal segments. And we define the septal segments in relation to the position of the right ventricular free wall. So, the
[00:02:00] anteroseptal and inferoseptal segments are bounded by the anterior and inferior insertion points of the right ventricle. This is also true at the mid-left ventricular level. Where again, we have six segments, named as before. We identify the mid-level by the presence of the papillary muscles, here. And then the apical level, we have four segments: anterior,
[00:02:30] lateral, inferior, and septal. And again, the septal segment is defined by the attachment points of the right ventricle. And one of the key uses of this multi-segment model is that we can relate abnormalities, in the segments, to the coronary artery that usually supplies them. So, we know that the left anterior descending coronary artery usually supplies the anterior and anteroseptal segments at the basal
[00:03:00] and mid-left ventricular levels. And apically, it usually supplies both the anterior and the septal segments. The right coronary artery normally supplies the basal and mid inferior and inferoseptal segments and the apical inferior segment. And the circumflex coronary artery normally supplies the basal and mid anterolateral and inferolateral segments and also the
[00:03:30] apical lateral segment. Although, the relative supply of both the circumflex and right coronary arteries depends upon arterial dominance. In most cases, the right coronary artery is the dominant artery. When describing regional wall motion, we normally do so using this 16-segment model. When we describe myocardial perfusion, which you can learn more about in our chapter on myocardial perfusion imaging, then we sometimes include a 17th
[00:04:00] segment, which is the apical cap at the very tip of the left ventricle. That is also normally supplied by the LAD. So, let's take a look at some long-axis views of the heart obtained on CMR imaging and these correspond to views that you may already be familiar with using echocardiography. So, let's begin with the four-chamber view and we have the left ventricle here, the left atrium and the mitral valve. We have the right ventricle,
[00:04:30] the tricuspid valve, and the right atrium, here. And looking at the left ventricular segments, we have the basal segments, the mid-cavity segments, here and the apical segments, here. And we have the basal inferoseptum, the mid inferoseptum, and the apical septum. And we have the basal anterolateral segment, the mid anterolateral segment,
[00:05:00] and the apical lateral segment. Normally, we look at the left ventricle on cine image. This allows us to assess systolic function and this is the equivalent four-chamber cine-CMR view and we can quite clearly assess wall motion and myocardial thickening in each of these six segments. Moving on to the two-chamber view, we have
[00:05:30] the left ventricle, the mitral valve, and the left atrium, here. And we have the basal, mid, and apical segments. So, we have the basal anterior segment, the mid-anterior segment, and the apical anterior segment. And we also have the basal inferior segment, the mid inferior segment, and the apical inferior segment. So, the anterior wall and the inferior
[00:06:00] wall seen in the two-chamber view. And again, here, is the cine-CMR image that allows us to assess systolic function. So, we have the anterior segments, the inferior segments and we can assess wall motion and myocardial thickening all of which is normal in this image. And then our next view is the three-chamber view, so we have the left ventricle, mitral valve, and left atrium. We have
[00:06:30] the aortic valve and aortic root and we can just see the right ventricular outflow tract, here. And so here, we have got the basal anteroseptal segment, the mid anteroseptal segment, and the apical septal segment. And we have the basal inferolateral segment, the mid inferolateral segment, and the apical lateral segment.
[00:07:00] And once again, here's the equivalent cine-CMR image. So again, we have the left ventricular segments clearly seen with the movement and thickening during systole and again, regional wall motion is normal throughout, in this case. So, looking at the four-, two-, and three-chamber views, we can get an eyeball assessment of overall left ventricular systolic function and also
[00:07:30] we can inspect the regional wall motion of each of the 16 myocardial segments.