Imaging Part II - CT and Echocardiography
Before we jump right in, I just wanted to briefly introduce myself. My name is Duc Giao, and I am a fourth-year medical student at Harvard Medical School. I will be joining Adham in writing some of these posts moving forward. We hope that you are enjoying and finding our posts helpful. Today, we will be doing an additional segment on imaging to round out our topic this month.
Now that you are familiar with echocardiography and CT from our last two weeks, today, we will be discussing why imaging is important for detecting aortic dissections and for surveillance of aortic aneurysms. As you may already know, an aortic dissection occurs when there is a tear in the inner layer of the aorta, causing blood to seep in and build-up between the layers of the vessel. If not treated emergently, could be fatal. On the other hand, an aortic aneurysm is when there is a balloon-like bulge or increase in size of the aorta, which can lead to a dissection or rupture. These definitions are important as this is what would show up on CT on echocardiography.
A CT scan is very important when there is suspicion for an aortic dissection as it shows how much of the aorta is involved and whether any other arteries that come off of the aorta are also affected. As shown in the left of this figure here, both A (ascending) and D (descending) parts of the aorta are involved. Another view of this aorta from the side confirms dissection involving the ascending and descending parts of the aorta.
Source: St. Vincent’s University Hospital
Likewise, in patients with aortic aneurysms, there is a particular bulge or large size of the aorta, which is seen in the much larger size of “A” compared to “D” on this image. For the most part, the diameter of the aorta is more or less the same size throughout. Routine imaging with CT and echocardiography allows for cardiologists and cardiothoracic surgeons to monitor a patient’s aneurysm predict when the appropriate time for surgery is right.
Source: Isselbacher EM “Thoracic and Abdominal Aortic Aneurysms” Circulation 2005.
Echocardiography is also another way in which doctors can monitor the size of patient’s aneurysms. Here in the image below, the ascending aorta is large or “dilated”. This is apparent as the size of this segment of the aorta appears to be the same size as the left ventricle of the heart (denoted as “LV”), which is abnormal.
Source: Isselbacher EM “Thoracic and Abdominal Aortic Aneurysms” Circulation 2005.
And that is all for this month about imaging for aortic dissection and aneurysms. Today’s segment was a deeper dive into imaging and we hope it sheds light into why these imaging tests are done. We hope you are enjoying these weekly posts and would love to have you join us again next week. Be safe and healthy, and always remember to Think Aorta! Thanks everyone.
- Duc