Vascular Imaging of the Head and Neck – Pathology
This lecture is the third part of a capstone course we have for our 4th year medical students. In the first lecture, we discussed general concepts about how to approach vascular imaging of the head and neck, including angiography, CT angiography, MR angiography, and ultrasound. The second part of the lecture covers a general search pattern for vascular imaging of the head and neck on a CT angiogram. To see more about this course, check out the full vascular capstone page. It contains interactive cases that you can scroll on your own as well as some additional videos explaining them.
In this lecture, we welcome back our special guest, Dr. Cynthia Wu, who is going to go over some of the common pathologies you might encounter on vascular imaging of the head and neck.
There are a few common pathologies you might be looking for on vascular imaging of the head and neck, including aneurysm, thrombosis, dissection, and vascular malformations. Read on to learn more about each one.
Aneurysms are abnormal outpouchings of the vessels. Sometimes they contain all the layers of the vessel wall (true aneurysms) or may be contained ruptures of one or more of the walls (false aneurysms, or pseudoaneurysms). Most intracranial aneurysms are true aneurysms while aneurysms in the neck are pseudoaneurysms.
Thrombosis is occlusion of a vessel secondary to a blood clot. This is most commonly seen or suspected in the setting of a stroke, and can arise from rupture of an atherosclerotic plaque or from transmission of a thrombus more proximal in the circulation, such as from a cardiac valve or in the internal carotid artery. Most of the time, a thrombus will appear as abrupt severe narrowing or truncation of a vessel.
Thrombosis can also occur in veins, such as the dural venous sinuses. Venous thrombus will more commonly appear as a central filling defect.
Dissection is a tear or injury to the lining of the artery, or intima. In this case, then blood goes into the space between the layers of the vessel wall, an area known as the false lumen. When the vessel is large enough, this vessel may fill with contrast on the injection, but in smaller vessels this may thrombose and be seen as a smooth tapering or narrowing of the vessel that can even result in occlusion. You can also sometimes get irregular enlargement of the vessel past it, or pseudoaneurysm.
Arteriovenous malformations, or AVMs, are abnormal clusters of vessels which have abnormal connections between the terminal arteries and veins. This results in a shunt, or passage of blood from an artery to a vein without a terminal capillary bed. Arteries and veins then are enlarged and at higher risk of rupture. The Spetzler Martin grading system is a grading system used to rate the risk of surgical mortality on resection which can help guide management.
Once you’ve finished this video, I recommend moving on to the next section of the vascular capstone, where you can review individual browseable cases with explanations. The capstone overview is here, if you’d like to see all the cases and videos.
Or, see all of the vascular capstone videos in the vascular imaging capstone playlist.