Hey, good morning all and welcome to this year's AANS APP course. I've been asked to speak to you about basic interpretation of angiograms, angiographic anatomy, and I have a ton to cover in the next 30 minutes. I have no disclosures. I want to start just with basic normal anatomy and you know whenever we think about cerebral angiograms, whether we do radial or femoral access, really everything starts at the aortic arch. So you have the innominate artery giving off the right carotid, common carotid, and right vertebral artery. The left common carotid artery normally comes off of the aortic arch but can come off of the innominate and then the subclavian artery will give off the left vertebral artery. There are variations, as I said, so the left common carotid artery can come off the innominate. It can also come off of the right common carotid artery but this is what you may have heard referred to as a bovine arch. Another variation is that the left vertebral artery can come directly off of the aortic arch as opposed to the subclavian. This talk, besides telling you about normal anatomy, I also want to sort of show you different pathologies and how we identify where those pathologies are coming from and so I'll show you abnormal anatomy, how it pertains to angiographic interpretation. So when we're catheterizing vessels off of the aortic arch, there's different types of arch. So type one is typically seen in a young patient where the vessels come straight off the apex of the arch. Type two is where the vessels are slightly sloped over to the ascending aorta. Type three, everything's towards the ascending aorta and we see this in older patients as the vessels become more tortuous but sometimes that can also just be congenitally how your arch was formed. To talk about the carotid arteries, these are the two branches. We all know what the carotid arteries do but they were named after, the term was parotides or soparales or the sleepy arteries because it was recognized that occlusion of these arteries would cause you to fall asleep or lose consciousness. One of the first to describe how plaque in the carotid arteries could cause stroke was neurologist C. Miller Fisher who recognized the plaque could cause stroke in about 1951 and then Dr. DeBakey was one of the first who actually had performed a successful carotid endarterectomy. If you look at the timeline of when carotid disease was first recognized and treated, you compare that to the very first carotid angiogram which was performed by Moniz in 1927 and the first carotid angioplasty actually was done by Dr. Kerber in 1980. So cerebral angiography and certainly neurointervention is a relatively new field. I mean the very first aneurysm coil was placed in around 1994-1995. So this is a newer field even though the anatomy obviously has been known for a long time. So there are other variants that from the normal textbook anatomy. So for example, anomalous origin of the right vertebral artery coming off of the left subclavian artery which is very rare. Left vertebral artery off of the arch which I talked about. So not every patient has a classic arch. This is just a video of a coronal CT angiogram and as I scroll you're going to see the aortic arch come into view here. This is the aortic arch where my arrow is. This is the anominate artery coming off. This is the left common carotid artery. That's where it's supposed to be. If I go back you can see the right common carotid coming off the arch. The right vertebral comes off after the common carotid artery and then here comes the subclavian artery into view. Actually on this one you can see the vertebral artery is coming directly off the arch here. So that was a little bit of an anomaly. This is the right common carotid artery with a calcified plaque and stenosis. So that's what we would call a carotid internal carotid artery stenosis. Most stenosis occur at the bifurcation. You can see that on this CT angiogram as well and this is a heavily calcified plaque so the contract is barely getting through but both on where I'm circling the sagittal and the coronal this plaque is heavily calcified and then on the DSA angiogram, subtracted angiogram, you see that that's about a 90 percent, 99 percent stenosis. This is a patient who would need an endarterectomy because the balloons are not going to open up that heavily calcified plaque. So you know we've talked about the arch now we'll go to the carotid anatomy. The external carotid artery has multiple branches called superior thyroid, ascending pharyngeal, lingual, facial occipital, posterior vascular, internal maxillary or IMAX. The middle meningeal artery comes off of the IMAX in a superficial temporal. So here's just an angiographic view of those branches as well as sort of a cartoon view of those branches and the catheter is in the external carotid artery. You see the occipital here this is the IMAX superficial temporal and then middle meningeal which is relevant increasingly as we do MMA embolizations for subterraneals. The external carotid artery has many many anastomoses to intracranial circulation, the ophthalmic artery. So for example when we do MMA embolizations we have to look for these dangerous anastomoses because one of the biggest risks with MMA embolization is blindness where you might have an ophthalmic artery coming off of a middle meningeal artery or an anterior falsene artery that retrograde fills the ophthalmic artery. So that can cause blindness. You can also have branches from the petrous ICA that anastomose with the ascending pharyngeal IMAX and MMA vessels that could cause stroke or cranial nerve palsies. In terms of the internal carotid artery there really aren't any aren't supposed to be any branches coming off of the cervical ICA but there's segments of the cervical ICA including this cervical petrous which is called C2. C3 is the lacerum segment because it traverses the pharyngeal lacerum. The cavernous segment binodal ophthalmic and communicating segment and typically you don't have branches until the ophthalmic segment except for maybe some small perforators to the pituitary gland. So as I said I'm going to go over pathology to sort of discuss location of the segments of the carotid as well as normal anatomy. So I have this collection of animal shaped aneurysms. So here's a little dog shaped aneurysm. This would be you could say it's sort of at the lacerum pre-cavernous. Here's the cavernous segment of the carotid artery and as the petrous comes over to lacerum. So I would say maybe that's a lacerum aneurysm or really really proximal cavernous. You could go either way with that one. And then why is the these segments are very important because it's really you're looking at where the carotid artery enters the enters the dura or the dural rate because anything proximal to that does not put you at risk for subarachnoid hemorrhage but distal to that does. And so when we're following aneurysms or deciding whether to treat an aneurysm the location is very important. Then the internal carotid artery does have branches. I mentioned the superior hypothesia which goes to the hypothesis or pituitary, ophthalmic, PCOM, anterocaroidal, anterocerebral, middle cerebral. This is an aneurysm of the superior hypothesial segment kind of a horse face looking aneurysm there. This is after a pipeline stent went across it so you see stasis in the aneurysm or sometimes it looks like Snoopy's nose too. This is an aneurysm that's also superior hypothesial sort of looks like a goat. They come medially off the carotid artery and so that's how you can kind of tell between cavernous. If it's really distal cavernous or superior hypothesial these are pointing medially proximal to the ophthalmic segment. This is an ophthalmic segment aneurysm. You can actually see the head of the elephant goes into the ophthalmic artery and then just proximal to that there's another little ball it's like an elephant on a little circus ball. The ball is superior hypothesial segment. Now here's another ophthalmic aneurysm. If you look at the circle of Willis which we'll go into next, I'm going to talk about the segments of the circle of Willis but basically you need 10 components for a complete circle. Not all people have only so 90% of patients have a complete circle and then functionally present 40% meaning about 40% of patients if you occlude a carotid will they not have any symptoms because the circle of Willis is functionally present. So to have a complete circle you need two carotids, two vertebrae, two anterior cerebral arteries, communicating, an ACOM, a PCOM, two PCAs, and a basilar artery. Really you only need one vertebral artery because as long as the basilar fills you're okay but to have all components you should have two vertebrae. So here's a patient who has no carotid arteries but is filling both internal carotids intracranially through the PCOMs retrograde from the basilar. So when I say no carotids I mean the cervical carotids are occluded but still is not having strokes because of the vertebral arteries and basilar system in the circle of Willis. There are other anomalies which can be normal and congenital such as the fenestration seen here at the anterior communicating artery. These are areas that can be risk factors for developing aneurysms. And then we talked about suprapothiceal and ophthalmic. Now we have additional ICA branches including PCOM, anterocardial, ACA, and MCA. So this is an aneurysm at the PCOM posterior communicating artery segment and it looks like Scooby-Doo. This is also a PCOM aneurysm. This one has a large where the last one had a very small PCOM. This one has what we would call a fetal PCA meaning that the PCA comes off of the carotid as opposed to the basilar artery and so this one you wouldn't want to occlude this PCOM if you were treating it because that could cause a PCA stroke. This is you probably heard the term infundibulum. This is not actually an aneurysm but it's a good example of the anatomy here. So you see the ophthalmic artery that I'm pointing at with my pointer. Then here's an infundibulum which is this triangular widening of the origin of the PCOM and then above that, you see the anterocaroidal arteries, so you can see all of those branches really nicely. This is a carotid terminus aneurysm, meaning it's at the apex of the end of the carotid artery before it bifurcates into MCA and ACA. The ACA has the following branches. So A1 is the segment directly off the carotid. It has the perforating arteries, the recurrent artery of humer, which sometimes comes off A2 as well. A2 has the orbitofrontal, frontal polar arteries, and then pericallosal and callosomarginal are branches off of that. So, let's see. Here's just a video of a 3D rotation. You can see an aneurysm here at the A1, A2 segment. And you can also see cross-filling across to the other A1 segment. This is an aneurysm. Here's recurrent artery of humer, and a little cowhead-shaped aneurysm at the A1, A2 segment as well. This is what I would call a true A-comb aneurysm, meaning as opposed to coming off where A1 and A2 branch, it's actually coming off the anterior communicating artery, but this is a dominant A1, meaning there is not an A1 on the other side. So the circle of Willis is not complete. Both A2s come off of one A1, and then this aneurysm looks like a crocodile is coming right off the anterior communicating artery there. Here's another. I like this one because it looks like it has legs. So this one is another true A-comb aneurysm coming off the anterior communicating artery. This one is another. Here's a dominant A1, meaning there's not an A1 on the other side. A2s, and this is a really nice view of a true A-comb because you can see the anterior communicating artery is this crossbar here, if you think of like goalposts, and it's sitting right on the crossbar. This one is an example of a little more distal, and I would call this really A1, A2 on the right side. Now we go distal even more into the pericolosal, colosomarginal, so they're named for where they are. So pericolosal goes around the corpus callosum. Colosomargin goes around the margin of the pericolosal. This is a common place for aneurysms, so it's all branching points. And this little aneurysm is sitting at that bifurcation of colosomarginal pericolosal. The MCA now has branches as well. M1 includes the lateral articular striates in the anterior temporal artery. M2 has a superior division, inferior division, sometimes a trifurcation. And the M3 branches are branches off of the M2. This is another way to look at it anatomically. So before we were doing a lot of angiograms, the segments were based on where they come out of the sylvian fissure as opposed to the branching points. So old anatomical texts would say M2 is like the insular segment, M3 opercular, and M4 is where the MCA is over the cortex. But from an angiographic standpoint, and when we're doing thrombectomies, we actually say M1, M2, M3 is based on the order of branches as they come off, as they branch, as opposed to anatomically, where they come out of the sylvian fissure. So you will see the definitions of these. They can be different based on really historically when they were named. This is a middle cerebral artery bifurcation aneurysm. It was a very ugly, wide neck aneurysm that had to be clipped. The only thing I could think it looked like was this Jabba the Hutt guy. And so this is post-clipping intraoperative angiogram. You can see this is a trifurcation. Three branches of the MCA are coming out of the neck of this aneurysm. This is a bit of a stretch, but I looked really close and I thought I saw Elvis in this one. This is another MCA bifurcation aneurysm. This is an ugly teardrop aneurysm off of an MCA trifurcation. Another one that had to be clipped, but you can see this is M1 here, and then we're calling M2 all of these branches. And that's again important when we look at anatomy for stroke. So this is what I would call an M1 occlusion, distal M1, and you have some filling at the bifurcation of the neck. This is one of the M2 segments, but there's all this fuzzy clot at the bifurcation. We can get our catheter past there, get a stent retriever in place, pull out the clot. And now actually you see there's three M2s. So this was a trifurcation occlusion. Let's talk about the posterior circulation quickly. The vertebral artery comes from the posterior superior athletic subclavian artery. There's four discrete segments, V1, V2, V3, and V4. V4 is actually the intracranial portion. So that's very relevant in terms of aneurysms, AVMs. And it unites with the contralateral V4 segment to become the basilar artery. This is where you will get your posterior inferior cerebellar artery branches, anterior spinal artery, and perforating arteries to the brainstem. So this is the posterior inferior cerebellar artery. This is a picate, flow-related aneurysm to an AVM, another stretch, but sort of looks like a fluffy dog. And the basilar artery has the following branches, anterior inferior cerebellar artery, superior cerebellar artery, and then gives off both PCAs. You can see the branches here in this anatomic section. This is the anterior spinal artery, which is a nice rendition of that. So then you have the thalamic perforating arteries called the arteries of Percheron. This is pathology. You see an aneurysm here at the SCA origin, and then actually this ugly fusiform PCA aneurysm. This one has like a triplication of the superior cerebellar artery on the left. Here's anterior inferior cerebellar artery. Here's a basilar occlusion. So you can see both vertebral arteries, both posterior, both picas, but the mid-basilar is occluded. After recanalization, you can see now that both PCAs are filling both ICAs and both SCAs. And we talked about this a little bit already. So here is an AVM fed by a fetal PCA. We talked about that. It means the PCA comes off of the carotid. Here's a video of that. Now, if we're gonna talk about AVMs, we need to learn a little bit about the venous anatomy. So here's normal venous anatomy with both venous anatomy and normal venous anatomy. Both transverse sinuses, superior sagittal sinus, sigmoid sinuses filling. I'm gonna show you that here in cartoon form. Here's superior sagittal sinus, straight sinus, transverse sinuses bilaterally. Usually there's a dominant and non-dominant one. In vein of galen, intercerebral, thalamus, dry veins. Venous anatomy is obviously very relevant when it comes to arteriovenous malformations. Here's another view. You have co-dominant transverse sinuses, sigmoid sinuses and jugular veins with a nice superior inferior sagittal sinuses here. Just another cartoon of the sinuses. This is, you might've heard venous sinus stenting for pseudotumor cerebri or idiopathic intracranial hypertension. This is an example of a stenosis and measuring pressures to decide if the patient needs a stent. So the pressure approximately was two and then 30 beyond it, which says there's a pressure gradient against that stenosis in a patient who might benefit from stenting. Here's sinus thrombosis. You can see really fuzzy thrombus within the superior sagittal sinus here. I just want to get into AVMs very quickly in the last five minutes. I like to think of AVMs as like a bag of worms. And so it's really an abnormal connection of an artery and a vein with an intervening nidus. So you see arterial phase, here's the nidus and here's the venous phase. We think AVMs typically bleed due to venous hypertension. You can see there's feeders from the PCA here as well as the MCA. There's a venous stenosis here. We think that because of the pressure head at this area of the stenosis, that that can cause the venous varix to rupture and cause bleeding. And just another example, here's a micro catheter in that PCA, sorry, slide your goal over, in that PCA feeder. And we can see the arterial phase, the nidus and the venous phase as we're embolizing. So I know that was a very quick entry into venous anatomy, or excuse me, angiographic anatomy. I think looking at the pathology helps you understand the anatomy and the locations where you see aneurysms, AVMs, occlusions, things like that. So in order to identify abnormal anatomy angiographically, you need to identify abnormally, you have to have an understanding of the normal. And this comes from looking at as many angiograms as you can. Non-invasive vascular imaging can give you an understanding of the anatomy before you ever meet the patient. So if a patient's flying from an outside hospital and you wanna know what does the aortic arch look like, what kind of devices am I gonna need to do this thrombectomy or aneurysm treatment, the CTA is very important. And then again, understanding where pathology occurs can help with understanding of anatomic lag marks and segments. So we have a couple minutes for questions. Thank you so much, Dr. Benning. I do just have a simple question. Just any decision-making that you do for your approach to the angiogram if it's radial or ephemeral approach? Yeah, good question. I tend to do radial for all my diagnostic angiograms because these are outpatients, the patients can sit up right away and they don't have to be flat or bedrest and pack you. Any pathology coming off the vertebral arteries, I tend to go radial just because it's a very straightforward approach. Some folks are doing radial for everything. I tend to take a more nuanced approach just depending on location of the pathology. And I do still do my thrombectomies from ephemeral approach just because personally, I've seen a lot of radial artery complications with some of the larger bore catheters that are used for thrombectomy. Not so much in my own hands, but just you see these nightmare cases at conferences that you wanna avoid. So yeah, it's a little bit case by case. Okay, thank you so much. And just over the years, endovascular neurosurgery just has changed so much the outcomes of people with several arachnoids and strokes. It's been amazing to see. Yeah, it changes. It's funny because you'll write a chapter for a textbook and then by the time the textbook has been published, it already needs an update because the field changes so quickly. So, yes. Yes. All right, thank you so much for, and please join us for her lecture after the next lecture where she talks about vascular injuries. Thank you. Thank you, Laura.

angiographic anatomy

cerebral angiograms

vascular variations

cerebrovascular pathologies

carotid and vertebral arteries

angiography approaches