Identify normal heart structures on a cardiac CT scan

In this video, you'll be taken on a journey through the heart. With the aid of multiplanar imaging, Dr Rajani will be your guide on a detailed, visual tour through various heart structures–from taking a general look at the four chambers right down to visualising the entry points of various arteries.

Want to learn how to perform and interpret your own cardiac CT scans? Our Cardiac CT Essentials course was designed and delivered by CT guru Dr Ronak Rajani. Consultant cardiologist, lecturer at King's College London, and Director of the London Advanced Cardiac CT Academy, Dr Rajani will be your comprehensive guide to the ins and outs of cardiac CT application in a clinical environment.

[00:00:00] During this lesson, we're going to learn how to identify the normal heart structures on a cardiac CT scan. We are going to start at the top of the heart, at the level of the main pulmonary artery and work our way down to the inferior aspect of the heart. Let us first consider the overall anatomy of the heart. Here, we can see that the right atrium is connected to the right ventricle, and the right ventricle transitions into the right ventricular outflow tract before passing blood through

[00:00:30] the pulmonary valve and through into the main pulmonary artery. Here, we can see the left ventricle. Please pay note to the various coronary arteries that can be seen on the scan. We can see that the right coronary artery emerges from the aortic root, before it becomes the ascending aorta, and the right coronary artery passes down the right-sided atrioventricular groove. Here, we can see the left anterior descending artery, which emerges from behind the main pulmonary artery and is connected to the aortic

[00:01:00] root. The left anterior descending artery passes down the anterior interventricular groove. Let us now see how these structures appear on the CT scan. Take a moment to look through the CT dataset, that we're going to be evaluating. Try and focus on any cardiac structures that you are able to identify.

[00:01:30] Let's start at the beginning, at the level of the main pulmonary artery. On this side, we can see using multiplanar imaging, with the axial dataset in the top left-hand image, the coronal CT dataset in the bottom left-hand image, and the sagittal plane in the bottom right-hand window. We're now looking at the dataset at the level of the main pulmonary artery. Let us first look at the structures in the axial plane. Here, we can see, at the

[00:02:00] level of the main pulmonary artery, a number of different structures. We can see that the main pulmonary artery bifurcates into the right pulmonary artery and also the left pulmonary artery. We can see one of the pulmonary veins, the tip of the left atrial appendage, and also the ascending and descending aorta. In the coronal views and the sagittal views, we are starting to see more structures. Notice that the right ventricular outflow tract and the right heart is closest to the sternum. We can also see

[00:02:30] the left atrium, the mitral valve, and the left ventricle, and also the descending aorta. In the coronal view, we can also see the right atrium and the main pulmonary artery. And we're now looking at the left ventricle on FAST. So, we see the left ventricle, the aortic valve, and the ascending aorta. To remind yourself, this is the level at which this image is taken. Let us now move down to the level of the aortic root. At this particular level, we can start to see a number of

[00:03:00] different structures that weren't seen at the level of the main pulmonary artery. The images in the coronal and also sagittal plane, however, remain the same because we're still able to image the length of the heart. Let us now take a closer look at this axial image. We can now see a number of different structures. We can see the tip of the right atrial appendage, the aortic root, from which the left main stem arises, the right ventricular outflow tract, and more of the pulmonary veins. We can see the left superior pulmonary vein,

[00:03:30] the left inferior pulmonary vein, the descending aorta. In addition, we can also see the left anterior descending artery. In the coronal plane, we see the same images that were seen at the level of the main pulmonary artery. Because the length of the scan is still incorporating the length of the heart. We can see once again the right atrium, the left ventricle, the aortic valve, and the ascending aorta, along with the main pulmonary artery, as we're looking front on to the heart. In the sagittal plane, in other words,

[00:04:00] the plane looking from one of the sides of the heart, we can see the right ventricular outflow tract, the pulmonary valve, and the main pulmonary artery lying closest to the sternum, along with the left atrium, the mitral valve, and the descending aorta, which is the structure the furthest distance away from the sternum. Let us now move to the level of the ventricular outflow tract. We can now see, on the axial image, even more structures being included on our imaging plane. We can see all

[00:04:30] three of the coronary arteries: the right coronary artery, the left anterior descending artery, and also the left circumflex artery. We can now see also the left atrium, the right inferior pulmonary vein, and the left inferior pulmonary vein. We can also see the most superior portion of the left ventricle, the transition into the left ventricular outflow tract, and also the cusps of the aortic valve. We can also see the right ventricular outflow tract, as the most anteriorly located structure. To remind ourselves,

[00:05:00] we can see the same structures in the coronal and sagittal views and this picture only changes if the axial crosshair position changes in the axial plane. Let us now move further down the image to the level of the four chambers. To remind ourselves, we can see the axial plane on the top left-hand image, the coronal plane on the bottom left-hand image, and the sagittal on the bottom right-hand image. Let us now look at the various structures that we can see at the midportion of the left ventricle. We can now see

[00:05:30] what we call the four-chamber view. We can see the left atrium, the mitral valve, and the left ventricle, the wall of the left ventricle, the right atrium, and the right ventricle. And we can also see the three coronary arteries: the right coronary artery, the left anterior descending artery, and also the left circumflex artery. This thin gray line, that you can see outside of the heart, is known as the parietal pericardium, whilst the visceral pericardium lies in closer position to the myocardium.

[00:06:00] The space between the visceral and the parietal pericardium is known as epicardial fat. As we move further down into the left ventricle, we can start to see a number above the different structures emerging. We can still see our right coronary artery, our left anterior descending artery, and our left circumflex artery but we now also see the inferior part of the left atrium. We can still see the left ventricle, the right ventricle, and the right atrium, and also the inferior vena cava, and the descending aorta.

[00:06:30] As before, the coronal and sagittal views remain unchanged. Here, we can focus more on the axial view at this plane, to remind ourselves the inferior part of the left atrium, the left ventricle, the right ventricle, and also the right atrium. As we move to the very bottom of the heart, we're now starting to see the inferior aspect of the right ventricle and also that of the left ventricle. We can see the axial plane, the coronal plane, and also

[00:07:00] the sagittal plane. And then the axial view, we can now see a number of different structures in closer detail. We can see the very bottom of the right atrium and the right ventricle. We can also see the bottom of the left ventricle. Connected to the right atrium is the coronary sinus, through which the coronary veins drain back into the right atrium. We can see the thoracic spine, the liver, and also the sternum. Now, that we have been through all of the cardiac structures, are you able to identify these from the axial dataset alone?

[00:08:00] Now, looking at the 3D volume rendered image. Are you able to name the structures that you can see, as the image rotates around in the field of view?

[00:08:30] Take some time to look at this axial dataset and practice in your mind identifying the various different structures.

[00:09:00] Although not all cardiac CT scans are identical, knowing the normal connections and chambers of the heart can make the identification of abnormal easy.