Vascular Imaging of the Head and Neck – Case A

This case is the first of four cases that go with the vascular capstone course. On that page, there is a scrollable case that you can go through to teach you how to approach a CTA of the head in a real patient.

This case is an 80 year-old woman who presented with altered mental status. Take a look and see what you think before continuing on.

The patient in this case has subarachnoid and parenchymal hemorrhage on a noncontrast CT. Because aneurysms and vascular malformations are possible causes of subarachnoid hemorrhage, we proceeded with vascular imaging, or a CT angiogram of the head, to look for aneurysms or other possible vascular causes. Remember, for an intracranial hemorrhage you don’t need the CTA of the neck because these don’t commonly have any pathology that can explain intracranial hemorrhage.

On the CTA, you see multiple abnormal outpouchings of the intracranial vessels, otherwise known as an aneurysm. Intracranial aneurysms are abnormal outpouchings of the vessels thatt contain all the layers of the vessel wall (true aneurysms). They have a risk of rupture of several percent per year, and can be treated with surgical clipping or endovascular methods such as coils. Remember, it is common for patients to have more than one aneurysm, as is seen in this case.

Once you’ve finished this video, I recommend going back to the vascular capstone course, where you can review the other 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.

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.

Common pathologies

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

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

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

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.

Vascular malformations

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.

What’s next?

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.

Introduction to Vascular Imaging of the Head and Neck

This lecture is the first part of a capstone course we have for our 4th year medical students about how to approach vascular imaging of the head and neck, including angiography, CT angiography, MR angiography, and ultrasound. 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 have a special guest, Dr. Cynthia Wu, who is going to explain to us some of the general concepts behind vascular imaging of the head and neck, different techniques you can do to perform vascular imaging, and when you might order each type of study.

Basic concepts

In general, to see vessels better on imaging, we need to use some sort of contrast to differentiate the vessels from the surrounding tissues. For techniques like CT, we can use an injected contrast agent to see the vessels. For other techniques such as MR angiography and ultrasound, we can use intrinsic properties of flowing blood to emphasize the vessels.

This section covers the key concepts behind how we see the vessels for these major techniques.

When do I order these tests?

Once you know about the different possible techniques, then you have to figure out when you would possibly order them. Each technique (CTA, MRA, and US) have different advantages and disadvantages that make them more or less suited to different scenarios.

What’s next?

Once you’ve finished this video, I recommend moving on to the next section of the vascular capstone, where you can learn a general strategy for interpreting a CT angiogram of the head and neck.

The capstone overview is here, if you’d like to see all the browseable cases and videos.

Or, see all of the vascular capstone videos in the vascular imaging capstone playlist.

How to read a CT angiogram (CTA) of the Head and Neck

With increasing ability to image vascular phenomena, such as stroke and vascular malformations, through the use of very efficient and high speed computed tomography scanner (CT), we now have the ability to perform angiographic imaging of large segments of the body at one time. This has led to an explosion of vascular imaging of the head and neck to look for a variety of pathologies, including stroke, vascular malformations, and other vascular abnormalities. Every starting radiology resident needs a firm foundation in how to interpret these images.

Overview

Because there are a ton of images and a ton of structures that you need to look at, you really need a regimented approach, or search pattern, to use as you look through the images. In this video, I teach you how to look at a CT angiogram of the head and neck from start to finish so you can learn how to do it yourself. There are interactive examples that you can follow along on the vascular capstone page.

In this video, we go through a normal example.

I divide the study into the CTA of the neck, which I review first, and the CTA of the head, which I review second. My pattern goes as follows:

Nonvascular structures

I first like to look at all the nonvascular structures to make sure I’m not missing anything. I look at the lungs, the thyroid, the soft tissues of the neck (particularly to look for lymph nodes or mucosal masses), and the brain. I use a soft tissue window to look at these. Then I go back through with a bone window to look at the bones.

Neck Vessels

For the vessels of the neck, I use an approach that first does anterior vessels and then posterior vessels, moving from right to left. I follow the right common carotid artery through the bifurcation, and then follow the internal carotid to the skull base. I then repeat this pattern for the left carotid system. Then, I start from the right vertebral origin and follow it up to the skull base. Then the left vertebral artery. Once I’m finished, I restart at the skull base.

Head Vessels

For the vessels of the head, I follow a similar approach. I first follow the right ICA through the carotid terminus and then follow the right middle cerebral artery (MCA) and anterior cerebral artery(ACA). Once finished, I return to the skull base and repeat this pattern on the left. I then move to the posterior circulation, where I first follow the right vertebral artery, the basilar artery, and the right posterior cerebral artery (PCA). Then I repeat it on the left. My final search is to quickly look at the deep venous sinuses.

Summary

While others may have a different strategy, the most important part is to have a strategy and stick to it. This pattern of dividing the study into discrete sections will help you see all the findings and describe them accurately when reading cases on your own.

See all of the search pattern videos on the Search Pattern Playlist.

Board Review 3 – Case 18

Neuroradiology board review. This lecture is geared towards the ABR core exam for residents, but it would be useful for review for the ABR certifying exam or certificate of added qualification (CAQ) exam for neuroradiology.

More description and the answer (spoiler!) are seen below the video.

This case shows a patient with Horner’s syndrome who has subtle narrowing of the extracranial internal carotid artery on the left. On T1 fat-saturated imaging, there is a crescent of methemoglobin within the medial aspect of the vessel wall.

The diagnosis is: internal carotid artery dissection

Anytime a patient, particularly a young patient, has acute onset of neurologic symptoms, arterial dissection has to be on the differential. When it is accompanied by a Horner’s syndrome, internal carotid dissection is high on the differential because the sympathetic fibers for they eye travel alongside the carotid artery.

Arterial dissection is injury to the walls of the vessel. Most often the innermost layer, the intima, is separated from the deeper layers, the media and adventitia. It can be associated with a visible flap of lifted intima in the vessel and a portion of the vessel which is not carrying blood, a false lumen. When the vessel is disrupted enough to have visible dilation, this is a pseudoaneurysm.

In this case, the MR angiogram findings are quite subtle, but the key is the T1 fat-saturated images, which show a crescent of methemoglobin in the vessel wall. Fat saturation is required to differentiate this hyperintensity from the adjacent fat in the neck, which is also hyperintense.

Arterial dissection is associated with a variety of conditions, including trauma, fibromuscular dysplasia, vasculitis, and connective tissue disorders.

Board Review 3 – Case 15

Neuroradiology board review. This lecture is geared towards the ABR core exam for residents, but it would be useful for review for the ABR certifying exam or certificate of added qualification (CAQ) exam for neuroradiology.

More description and the answer (spoiler!) are seen below the video.

This case shows an avidly enhancing mass in the left neck which has the appearance of a tangle of vessels. These images are from a CT angiogram and the enhancement is very similar to the vascular structures, so you are likely looking at a vascular abnormality.

The diagnosis is: soft tissue arteriovenous malformation (AVM)

In this case, the abnormality has a lot of arterial enhancing components and there are associated abnormal veins, so there is a shunt between the arterial and venous structures, making this an AVM.

When looking at soft tissue vascular malformations, there is a relatively simple algorithm you can go through. If a mass has a soft tissue component, then it is a hemangioma because it has a proliferative mass component. If it has high flow components (like in this case), it is an arteriovenous malformation or AVM. If it has multiple cystic regions with fluid levels, it is a lymphatic malformation. The remaining abnormalities with slow flow vessels are venous malformations. There is a lot of overlap, with many vascular malformations having multiple components.

The treatment of these lesions is most commonly surgery, often with embolization before to reduce the amount of bleeding during resection. Sclerotherapy (or injection of a sclerotic agent through the skin) is usually not an option because these are high flow lesions and the agent will disperse to other areas in the body.

Board Review 2 – Case 14

Neuroradiology board review. This lecture is geared towards the ABR core exam for residents, but it would be useful for review for the ABR certifying exam or certificate of added qualification (CAQ) exam for neuroradiology.

More description and the answer (spoiler!) are seen below the video.

This case shows a patient with a new neurologic deficit and a relatively normal noncontrast head CT. Perfusion, on the other hand, shows an area of decreased CBV, increased MTT, and increased Tmax in the posterior aspect of the left middle cerebral artery (MCA) distribution. There is an associated vessel occlusion on CT angiogram.

The diagnosis is: cerebral ischemia (stroke)

This patient has an area of ischemia in the left MCA territory. Because the CBV is relatively maintained, this tissue is mostly considered penumbra. When there is a significant decrease in volume and flow, it is considered core infarct that is not likely to recover.

Board Review Cases – Vascular

This playlist is a collection of only the vascular imaging board review cases on this site. This includes primary vascular pathologies, such as stroke and vascular malformations

These cases are geared towards preparation for the radiology resident ABR core exam, although similar material is used for the ABR certifying exam general and neuroradiology sections as well as neuroradiology CAQ. The format of this playlist is case-based. Each case consists of a series of images followed by 1 or 2 questions. The first question is usually to name the diagnosis, while the second is a multiple choice question to test deeper understanding of the specific condition. Try to get the diagnosis before you see the second questions.

 

Board Review 2 – Case 6

Neuroradiology board review. This lecture is geared towards the ABR core exam for residents, but it would be useful for review for the ABR certifying exam or certificate of added qualification (CAQ) exam for neuroradiology.

More description and the answer (spoiler!) are seen below the video.

This case shows a CT with hyperdense blood tracking in the left basal ganglia and thalamus. Although the patient is relatively young, the location is strongly suspicious for hypertensive hemorrhage. Further evaluation for underlying causes, such as a vascular malformation or tumor, is warranted with vascular imaging (such as CTA) and MRI.

The diagnosis is: hypertensive hemorrhage

Board Review 2 – Case 5

Neuroradiology board review. This lecture is geared towards the ABR core exam for residents, but it would be useful for review for the ABR certifying exam or certificate of added qualification (CAQ) exam for neuroradiology.

More description and the answer (spoiler!) are seen below the video.

This case shows a patient with headache. Images are from an MR angiogram of the neck. The first few images show absence of filling of the left vertebral artery. This could theoretically be from atherosclerotic disease or thrombosis, but there is filling on a contrast enhanced MRA of the neck. This is because the flow in the vertebral artery is reversed in the setting of occlusion of the proximal subclavian artery.

The diagnosis is: subclavian steal