Ultrasound Assessment of the Aorta and Mesenteric Arteries - HD

Introduction

Hello, my name is Margarita Sson and I'm from Yale University School of Medicine.

Today I am gonna talk about ultrasound assessment of the aorta and mesentary ies.

I have nothing to disclose.

Anatomy and Hemodynamics of the Abdominal Aorta and Mesenteric Arteries

Today we're gonna talk about anatomy and hemodynamics of the abdominal aorta and mesentary ies.

We'll describe the techniques, image optimization and protocols for evaluation of the abdominal aorta and mesentary vessels will describe also role of ultrasound and evaluation of spectrum of pathologies of the abdominal aorta and mesenteric IES including dissection, aneurysm formation, and other sclerotic disease and occlusion and much more.

Aorta is approximately 13 centimeter long.

It has paired and unaired branches.

It lies anterior to the spine and it is approximately 20 centimeter, in diameter in its proximal portion, and it tapers down to 21 millimeter in diameter in its more distal portion at the level BI bifurcation.

This happens at the approximately level of L four in males.

The aorta is a little bit larger than females with difference of, three to five millimeter aorta lies anterior to the spine and posterior to the SMA as well as splenic vein mesentary IES take off from the ium with the first branch would be a select trunk that divides into the splenic left gastric common gastric arterial branches.

SMA, it takes off approximately one centimeter distal to the celiac tery and gives off four to six al branches.

Nine to 13 I branches.

IA colic right colic and middle colic arteries IMA is, lies approximately four centimeter from the bifurcation and it gives rise to the ascendant colonic artery and two descended branches on the transverse view.

On the transverse view, the STAC artery has a ts shape configuration or has, demonstrates a SGU sign.

And on the transverse view, SMA has a specific landmarks as with a splenic vein line anterior to it and the aorta line posterior to it.

And there is a fat ring that, separates the SMA from the other vessels.

There is a rich collateral circulation that allows communication between the three mesentary ies.

One of the, collateral circulations would be a pancreatic duodenal arcade that allows communication between the celiac artery and SMA.

Another one is a arc of lon that allows communication between the SMA and IMA.

And the third one is a marginal artery of Drummond that allows communication between the IMA and SMA.

And there is also branches of IMA and of internal IA IES that communicate and provide, collateralization, in the lower pelvis.

Therefore patients may remain asymptomatic despite of presence of severe mesenteric vascular disease.

There is a specific hemodynamics for the abdominal aorta.

Given its elastic features, it demonstrate phasic waveforms.

However, there is slight difference in the waveform appearance in the proximal aorta and in distal aorta in the proximal aorta.

There is a mode of diastolic flow, and this is due to take off, several branches that supplies and or and organs such as, spleen and liver, and kidneys.

And the distal ETA demonstrates less of diastolic flow because it supplies bilateral lower extremities.

Hemodynamics of the mesenteric arteries is somewhat different and it depends on perial state.

However, we will notice that in a celiac, trunk, the waveform pattern is independent of pre or postprandial state, and this is because, the celiac vessels and branches, supply and organs, which need a continuous, flow through the systole and diastole for the, spleen and liver and part of the stomach.

The SMA and IMA, demonstrate difference in the pattern of waveforms in the pre and postprandial state with increase in the diastolic flow in the postprandial state.

And this is because there is more of oxygenation requires in the bowel that is undergoing digestion.

Techniques, Image Optimization, and Protocols

When we evaluating, abdominal aorta and mesenteric vessels, we wanted to use, low frequency transducers because it allows us a evaluation of the deep structures and we will be able to visualize the aorta and branches very well.

We want to use anterior abdominal approach.

However, if there is too much of gas, in the, from the bowel, we can use, other approaches through the liver as an acoustic window or spleen using it as an acoustic window.

Also, when we evaluate vessels, we need to optimize parameters in the B mode.

Changing the focal zone gains, putting the harmonics on to making the images sharper to avoid the artifacts and to make sure that visualization of vessels in its origin is, very good.

And then we wanted to optimize your images on the color mode and color Doppler mode First needs to be adjusted for laminar flow in the normal vessel so that we can detect abnormality within the stenotic portion of the vessel.

Also in a spectral doppler, we want to make sure that we do the angle correction and, selecting it to less than 60 degrees so that we avoid, erroneously elevated peak systolic velocities.

Power duct is always helpful when you're looking for pcy of the vessels.

The usual protocol for assessment of the abdominal aorta includes initial survey of the aorta, and what we're looking for is atherosclerotic disease within the wall of the abdominal aorta or presence of dissection flaps, or presence of an aneurysm or occlusion or luminal narrowing.

Measurements are obtained in the longitudinal axis throughout day water in its proximal mid distal areas, as well as in the common IA ies.

And then we also, check day water and measure it in the transverse plane.

In the transverse plane, we obtain only one diameter, which would be left to right and important to remember not to put too much pressure on the aorta.

So we are not gonna end up with a flatten and spiritually increase the size of the transverse, diameter of the aorta.

When we measure the aorta, we wanted to put the cursors at the outer to outer wall and include the wall in the measurements.

When we evaluating mesenteric vessels, we also wanted to look at the water first and make sure that there is no significant other sclerotic plaques present, because if there are, there is a presence of other sclerotic plugs, your suspicion for presence of mesentery ischemia or stenosis is higher on differential and therefore you will be more closely evaluating these vessels.

Then when we are looking at the vessels, we wanted to see that there is no, areas of dilatation and other abnormalities, and we wanted to see that there is a normal laminino flow on Cala Doppler.

Again, this is the presentation of the celiac trunk with the branching vessels, demonstrating this T shape or sgu sign.

And a mesenteric, arteries such as SMA lies almost parallel, to the water when it's, takes off from it.

So initially we'll obtain systolic velocities in within the aorta at the level of the mesenteric arteries.

And then we wanted to obtain systolic velocities at the origin of the SMA proximal portion.

Mid portion distal portion of the mesenteric vessels is not usually well visualized, and therefore it does not have to be, interrogated.

We obtain the waveforms and analyze the waveforms, based on their pattern.

Abdominal Aortic Aneurysm

Abdominal aortic aneurysm is a very common, pathology and we wanted to make sure that we diagnose it correctly.

So to define the abdominal aortic aneurysm is, the focal dilatation of the abdominal aortic that is greater than three centimeter considered to be abnormal and aneurysmal if, there is a increase in the aortic diameter by 1.5 centimeter, greater times greater than adjacent unaffected segment, it's also considered to be aneurysmal.

And there is approximately 2.7 million of people affected in United States, and the risk factors include advanced age of greater than 65 years old, history of smoking, male gender, family history of connective tissue disease, and increased cholesterol level sclerotic disease or infection.

Patients usually are asymptomatic.

However, if there is an impeding rupture or, the true rupture is present, patients may present with a back pain, a low, blood pressures or bru artifact.

We usually differentiate abdominal aortic aneurysm by their shape, and dividing it to the fif formm appearance of the abdominal water.

Usually these are the true aneurysms and the cause of it, atherosclerosis.

And the second type is would be a ular, false aneurysm or pseudo aneurysm of the aorta.

And common cause of this kind is infection, mycotic aneurysm formation or due to trauma by location.

We divide abdominal aortic aneurysm to a supra renal, which involve the renal artery and extend proximally or juxta renal that, also involve the renal artery and extend distally or infrarenal that arise approximately 10 millimeter from the renal arteries and extend distally.

This is an example of supra renal abdominal aortic aneurysm, which originates at the level of the renal arteries and extend approximately.

And this is an example of the infrarenal abdominal aortic aneurysm that originates more than two centimeter from the SMA.

And this is the rule that we can apply to see what type of aneurysm we are dealing with.

Screening and Surveillance

Ultrasound is, most commonly used modality for screening and surveillance of the abdominal aortic aneurysm.

It has a very high accuracy of up to hundred percent.

Screening is usually offered to men who are, over 65 years old or who has a history of smoking.

The outcome is a reduction in modality from the triple A.

There is specific intervals that one should follow when you're dealing with abdominal aortic aneurysm based on its size.

So you wanted to screen annually when the abdominal aorta measures three to four centimeter and, you wanted to screen every six months.

If abdominal erda measures four to 4.5 centimeter in diameter, those which measure 4.5 to five centimeters should be screened three to six, months apart.

And those which are five to 5.5 centimeters should be screened every, every three months.

Rupture Risk

The biggest, risk that one has is, rupture of the AA and risk of rupture is related to the AAA growth rate and size.

Significant growth is considered when the abdominal aorta is growing greater than one centimeter in 12 months.

And risk of abdominal aorta rupture also depends on the size or diameter of the abdominal aorta.

For example, aorta of, that measures four to five centimeter in diameter will have a risk of rupture one to 3% per year.

And those, aaas that measure five to seven centimeters will have a six to 11% of rupture per year.

Those which are greater than seven centimeter will have a risk of rupture over 26% per year.

Statistics also depends on gender and predominantly women have a higher risk of rupture at the lower size of the aorta, aneurysm.

This is an example of the abdominal aortic aneurysm where we see that abdominal aorta is irregularly in shape and there is a complex fluid that is located anterior to the abdominal aorta and sort of drapes around it.

And, on the transverse image, again, you could see the complexity of the fluid that represents, blood that extravasates from the ruptured abdominal aortic aneurysm.

And the CT with contrast image demonstrates, hemorrhage in retroperitoneum associated, to, with the aneurysm rupture.

Management

There are, possible management includes open surgery or endovascular arterial um, repair.

There are two options available for treatment of the abdominal aortic aneurysms.

It includes open surgery or endovascular, stent graft placement.

The indications for surgery includes AAA diameter of greater than 5.5 centimeter or AAA size.

That is 2.5 times greater than the normal aortic diameter.

Also other, indication includes growth rates of greater than one centimeter per year, or if the patient's already presenting with rupture or if they presenting with symptoms concerning for rupture or impeding rupture.

Mesenteric Aneurysms and Pseudoaneurysms

Mesentary IES also can have, develop aneurysms and pseudo aneurysms.

The aneurysm are very uncommon in the mesenteric vessels.

They are potentially little, most commonly they affect hepatic, splenic and celiac arteries and causes usually a congenital or due to atherosclerotic disease.

Pseudo aneurysms represent, a contained arterial wall rupture.

And causes include blunt abdominal trauma, infection, inflammation such as pancreatitis or atrogenic causes after the biopsies.

Patients usually present with non-specific abdominal pain and the treatment of choice is endovascular embolization or stentin or surgical resection.

This is an example of celiac artery, so the aneurysm where we see that there is a focal dilatation of the distal celiac artery with yin yang phenomenon within the aneurysmal sac.

Given that there is a very short neck, you can't really visualize the neck itself and it's not gonna show, and demonstrate to and fro appearance of the waveforms expected within the neck.

Instead, you may find a very low resistance waveforms at the level of the neck just because of the width of the neck.

This is an example of common hepatic artery s the aneurysm that, is presented as a cystic structure with complexity within, in the area just anterior to the abdominal aorta.

And when you put the color doppler and optimize your imaging, you could see that there is a celiac artery that extends towards this, structure and then branches off.

And the visualized, vessel that was better seen on A CTA was a common hepatic artery that gave rise to this large partially thrombosis the aneurysm.

And this is, reformatted in the reconstructive M map images.

This is an example of gastroduodenal artery S aneurysm, and you have to believe that not always we can see the pseu aneurysm and aneurysm of the mesentery vessels in its branches so easily.

This just happened to be in the, at the level of the Port Haus and, as it's correlated nicely with this CT contrast image and, demonstrates very nice long neck, in association with the gastroduodenal artery.

Later on, this patient underwent angiogram where the aneurysm was embolized and coiled aortic dissection is a very common problem and we see it often, and it represents a separation of the intimal and medial layers of the aortic wall.

Aortic Dissection

Usually it represents an extension of the thoracic dissection or is associated with penetrating ulcers or aneurysms.

Causes also include the presence of atherosclerosis, hypertension, collagen vascular disease, cocaine use pregnancy trauma, preexisting aneurysms or ulcers.

It has a high mortality and morbidity and requires urgent care on a gray scale.

It is important to optimize your images in a way that you can visualize this echogenic line that represents a dissection flap.

And, usually the dissection flap, will separate the true lumen from the false lumen.

And as you see here on this cynic clip, that in the false lumen, the flow is slow.

And that is why you see all this, artifact within the lumen.

And the false lumen is usually larger.

You can also on a gray scale, detect the entry point as well as endpoint where the dissection stops.

Cala Doppler is utilized to assess for patency of the true and false lumen.

And you could see that in this scenario we have a false lumen that is still patent, and in the sly it demonstrates forward flow that is not presented on these images.

But in the diastole there is a retrograde in the false lumen.

And that's how also you can detect the abdominal aortic dissections, even though if you don't notice that there is a dissection flap, something to look for.

You can also utilize your spectral doppler to be able to differentiate the true lumen from the false lumen.

In the true lumen, the waveforms are more normal appearing and in the false lumen you may have, very abnormal looking disorganized waveforms Dissection can extend into the mesentery arteries, and sometimes mesentary arteries may have spontaneous dissections.

The causes of the spontaneous dissections may be either artery sclerosis or FMD or mycotic infection trauma.

Connective tissue diseases most frequently dissections affect SMA one thing to be worried about is for perfusion of the end organs and bowel.

When there is a dissection of mesentary gutter is notice.

So this is one of the examples where we have a dissection flap very well visualized and abdominal aorta and the dissection flap extends into the SMA, however, does not extend into the more distal portion of the SMA And we on color doppler imaging, we see that there is a, a normal forward flow in the true lumen and the retrograde flow in the false lumen of the aorta.

This is another example of dissection of the abdominal aorta with extension to the SMA.

However, here it is very difficult to see the dissection flap and colo Doppler images can be, utilized and, to assess the patency of the SMA as well as spectral doppler can be used to assess for possible stenosis in the vessel.

It is very important to interrogate the branches of the aorta when you see the dissection just because it may extend into not just SMA, but it may extend into the celiac and may extend into the renal vessels as well.

Like in this case, there is, no profusion of the right kidney because of the false lumen supplying the right main renal artery.

And this is an example of a spontaneous SMA dissection involving the mid portion of the SMA.

And we have a, a partial occlusion of the SMA and this is a correlative, CTA image where we see the dissection flap and partial thrombosis of the false lumen.

Atherosclerotic Disease

We're gonna move on to the evaluation of the artery sclerotic disease involving the, mesenteric arteries as well as the aorta.

Artero sclerosis is usually a most common type of occlusive arterial disease, and it's due to the development of a plaque that leads, in the long run to the luminal narrowing.

It is a chronic progressive disease and eventually leads to near complete or complete occlusion of the vessel On a gray scale, we can, assess the, plaque morphology and we can look if this is a hypo quick plaque, if it has, a surface that is irregular or smooth, if there are any calcifications within the plaque.

And that's how we can determine if the plaque is vulnerable or if the plaque is, indeed stable or mixed.

When there are calcifications detected, then you think about it's a stable plaque just because calcifications and, a large amount of fibrotic material within the plaque can, determine its stability.

When, there is a, a low attenuation within the plaque or, high genicity within the plaque, and there is a regular surface, this something that implies that there is a vulnerable plaque present and there is a very high, rate of embolization with the vulnerable plaques.

After that, we wanted to put the color doppler and evaluate for a presence of alias in within the possibly stenotic area of the abdominal aorta.

Once we detect the, possible alias in, you wanted to interrogate that vessel as well as you wanted to interrogate vessels that are more distally to the abdominal aorta.

Like in this example, we see that, right su superficial femoral artery demonstrates a tardis par with waveforms as well as the left one, and that implies on a significant stenosis within the distal abdominal erum.

Abdominal Aortic Occlusion

Abdominal aortic occlusions are due to preexisting atherosclerotic plaques and, peripheral vascular disease with prevalence in males in their fifties.

It may happen very rapidly and patients usually present with lower extremity pain at rest, claudication abdominal pain and impotence, full occlusions, can happen and extend from distal aorta up to the renal arteries.

Usually the SMA is rarely affected just because it's, a, it becomes a source of collateral blood flow to lower extremities, and the collateralization usually happen from the SMA, communicating with colonic arteries with IMA branches and then internal iliac arteries and then external iliac arteries.

And, there is always a very big concern for compromise of blood supply to the and organs, and you have to assess the renal kidney, I mean the renal profusion, as well as liver profusion and as well as spleen.

So this is an example of 81 years old patient who, had a worsening of shortness of breath and all UIA and presented with a right groin pain, right thigh numbness and tingling.

And on evaluation of her abdominal aorta, we find that there is a flow seen within the proximal abdominal aorta, however, no flow is detected within the mid and distal abdominal aorta up to the bifurcation and beyond.

The only flow that was detected also was in this, SMA and when we interrogated SMA, we saw that the systolic velocities were mildly elevated.

That likely was due to compensatory flow in the SMA that was serving as a collateral, blood supply to the lower extremities.

This is correlative images.

This is two months before, the abdominal worted demonstrate a contrast enhancement, on this, contrast enhanced ct.

And this one is obtained at the time of ultrasound, which demonstrates no flow or no enhancement in the abdominal aorta.

Distal to the SMA and SMA is nice and juicy and it provides a collateral flow towards the lower extremities arterial system.

Acute Mesenteric Arterial Occlusion

Acute mesenteric arterial occlusion also can be seen, however the cause is usually due to thromboembolic event and, such as at atrial fibrillation.

More chronic presentation of thrombus that we see usually on, follow up, ultrasound imaging, demonstrating, no flow within the occluded portion of the vessel.

And with reconstitution of a more distal portion of the vessel to optimize your images, you can actually detect a retrograde flow through the collateral circulation of the mesentary arcades that fills in the distal portion of the mesentary artery.

This is a more acute presentation of the, occlusion of the SMA with a cogenic focus scene within the mid portion of the SMA.

And this is the SMA.

We detect, very high resistance waveforms just proximal to the seclusion with loss of diastolic flow, just telling us that somewhere distally there is gonna be an occlusion present.

And correspondence, CTA images demonstrates, filling defect within the s distal and, mid to distal portion of the SMA.

Chronic Mesenteric Ischemia

We're gonna move on to evaluation of atherosclerotic disease in the mesenteric arteries.

Again, this is a progressive, plaque deposition near the osteo of the mesenteric arteries and may affect one or more mesenteric vessels if there is a significant stenosis present, or if there is a occlusion, it may compromise blood supply and cause bowel ischemia and result in chronic mesenteric ischemia.

Patients usually, as symptomatic due to rich collateral circulation if one or possibly two vessels are affected.

However, when there is a significant stenosis in more than two vessels, then patients will become symptomatic and present with abdominal pain that is related to meal intake.

Patients will be describing fear of food intake, bloating, weight loss, or diarrhea.

For the diagnosis of chronic mesenteric ischemia, it required to have at least two mesenteric vessels, de demonstrating significant stenosis.

The diagnostic criteria for mesenteric arterial stenosis of greater than 60% of lumen includes peak systolic velocity, mesenteric to aortic ratio, as well as anti diastolic velocity.

The combination of this, parameters improves the sensitivity and specificity for evaluation of the stenosis.

Big systolic velocities of greater than 200 in the celiac and IMA vessels are considered to be abnormal, as well as, presence of pix systolic velocity of greater than 275 is, reaching a threshold for stenosis.

Mesenteric to aortic ratio is, helpful to compensate for systemic processes such as thyroid, toxicosis, or pregnancy state that result in, high output states or also compensate for presence of septic shock in the system.

So we are not gonna interpret and misinterpret systolic velocities when we see the ratio that is greater or equal to 3.5 at consider to be abnormal.

To obtain this ratio, you wanted to take the mesenteric artery, peak systolic velocity and divide it by peak systolic velocity within the aorta at the level of the mesenteric vessels, and that's how you can obtain your ratio.

It is also was noted, it was also noted that an diastolic velocity increases in, areas of stenosis due to bowel ischemia that requires continuous flow through systole and diastole regardless of, pre or postprandial state.

The other thing that we always look for are secondary signs of arterial stenosis, and those include brewery artifact and brewery artifact can be noticed at the beginning of systole on the spectral doppler and represent a turbulent flow within the stenotic vessel.

Also, we looking for color, color alias in within the stenotic area, representing the high, p systolic velocities at the area of stenosis distally to stenosis.

We're looking for presence of tardis pars wave forms that are usually seen, in, very significant stenosis, more proximally.

So, tardive parwas waveforms are seen usually distally to a steno area.

Post steno dilatation is another, sign that allows us to evaluate more closely areas that are more proximal to it and make sure that there is no stenosis, responsible for this post-traumatic dilatation.

This is an example of a three vessel disease in the patient who was diagnosed with chronic mesenteric ischemia.

And in this patient, the systolic velocities within the, aorta was normal measuring up to 80 centimeter per second.

However, in all three mesentary arteries, we, found that there was markedly elevated py systolic velocities at the origins of each of these vessels.

Measuring up to 450 in, the celiac trunk and SMA 445 and an IMA systolic velocity was up to 300.

When you take the ratio of, mesenteric arterial systolic velocity to the aorta, you'll find that the ratios were also markedly elevated.

So this was concluded that there is a presence of significant stenosis in all of these three vessels, and that is why this, goes along with a diagnosis of chronic mesenteric ischemia.

Also, patient underwent MRA evaluation that demonstrates significant stenosis in all of these three vessels.

Management of Mesenteric Arterial Stenosis

How do we manage the mesenteric arterial, stenosis?

There is two major options available, and it would be re either endovascular or open surgical revascularization.

In endovascular repair.

The stent is usually placed at the level of stenosis, and then patients, are sent to for ultrasound assessment to make sure that there is no development of complications.

The major complications, include stent risk stenosis or stent occlusion.

On a gray scale imaging stent can be really readily visualized within the vessel, and usually you expect a protrusion of the stent into the lumen of the uta.

That's a normal positioning of the stent.

Then color doppler can be applied to see if the stent is filled with the, color to make sure the stent is patent.

On the gray scale images, we also can notice if there is any debris, debris within the stent, and that's gonna imply on presence of hyperplasia.

Spectral dopper is also utilized to assess, systolic velocities within the stent.

And although there is no strict criteria exist, we can use a baseline, systolic velocities obtained right after the surgery or after stent placement and compare to them, them with the follow up imaging.

This is an example of instant stenosis.

We have a stent within the Celia ery and, there is a lots of alias in within this vessel.

And, on a spectral doppler, we see that there is markedly elevated peak systolic velocity seen within the Celia ery and SMA.

Both of these vessels were stented and, distal to it.

Tardive spar was waveform were noted distal to the stenosis, and a stent, angiography was performed that confirmed instant stenosis.

And after balloon angioplasty, the flow was restored.

This is, ultrasound images that were obtained after balloon angioplasty with normalization of, pig systolic velocities as well as wave forms in, origins of the celiac and SMA other things to consider when you evaluating mesentary arteries, full presence of stenosis is, fibromuscular dysplasia.

Fibromuscular Dysplasia

Fibromuscular dysplasia affects usually medium-sized arteries and represents a proliferation of smooth muscle cells and fibrous tissue in the wall.

More commonly, it affects males at the younger age of presentation.

Most commonly affected arteries are renal arteries, and followed by carotids and then by mesenteric, 30% of them have cerebral aneurysms.

The classic appearance of the fibromuscular dysplasia in the vessel is, a detection of string of beads appearance, and this is, correlated to areas of narrowing and dilatation within the vessel.

Again, the most commonly areas affected, proximal on me or distal portions, but not the osteo of the vessels.

Osteos of the vessels usually affected by atherosclerotic disease.

The management is also different.

We don't place stents in the areas of FMD.

We usually use angioplasty of the stenosis vessels, segments.

Pitfalls in Diagnosis

Several pitfalls that you should be aware of when the diagnosing of, chronic mesenteric ischemia, a high output state such as pregnancy or thyrotoxicosis, low output state such as hypotensive shock, arrhythmia, or other pathologies such as median, a acute ligament or nutcracker syndrome.

High Output States

This is an example of a 30 years old patient who was pregnant and, abdo presented with abdominal pain.

And as you can see on this, color and spectral doppler images, the systolic velocities within the aorta is very high.

Measuring up to 170, the average velocity is up to a hundred.

And in the celiac, the systolic vir velocity reaches the criteria for stenosis and threshold for stenosis, the same as in the SMA.

However, if you take the ratio of mesentary, gut systolic velocity to the uh, aorta, you are not going to reach the abnormal greater than 3.5, ratio that you expect with stenosis.

That just represents that there is a high output state with, elevated systolic velocity seen throughout the entire arterial circulation.

Arrhythmia

This is an example of patient with a significant arrhythmia, and the question becomes which of these, peaks you have to be taking into consideration and which one you should be discarded.

So the ones which are mid-size peaks or the very high picks, that's the ones which you should, take into consideration and use for, evaluation of stenosis.

The small pigs usually represent an extra beats and, should not be, assessed, for Pyxis style elastase and should not be used.

Median Arcuate Ligament Syndrome

Now we're gonna talk about other pitfalls such as the median ar ligament syndrome, and this syndrome is related to, fibers, bent that is crosses over the celiac trunk and is causing, a mechanical stenosis of the vessel.

On c doppler, you could see that there is a fish hook appearance of the celiac trunk, and this is due to, a movement of the celiac trunk together with a fibrous band upward.

On the expiration on inspiration, the vessel usually returns to its, initial state.

Sometimes the stenosis is fixed, it usually seen in chronic cases.

And systolic locis could be elevated not just on expiration, but also on the inspiration.

So this is an example of, many ar ligament syndrome that demonstrates a hook like appearance of the, celiac trunk on expiration and more, straight appearance on inspiration.

On inspiration.

The systolic velocities are mildly abnormal, but not meeting the criteria of stenosis.

And when there with expiration, the systolic velocities, getting markedly elevated.

And this is, confirmed on the CTA image where we also see post stenotic dilatation and a sort of bending of the vessel On this Athena clip, you also can see that the change in the shape of the end configuration of the celiac trunk.

Nutcracker Syndrome

Another pitfall that you should be aware of is presence of, nutcracker syndrome.

And this is the, vascular compression disorder that is caused by compression of the left renal vein by SMA and uh, aorta.

And this is due to the very small angle of takeoff of the SMA less than 17 degrees from the aorta.

The usual angle of, takeoff of the SMA is 38 to 65 degrees.

The symptoms, the patients present with is left upper quadrant pain and microhematuria.

On kalo dola.

You look for alias in and elevated pi velocities in the left renal vein as it passes between the aorta and SMA left renal vein.

Posto dietician can be also seen as well as, enlargement of the binna vein.

So here we see that there is a left renal vein that crosses between the SMA and the aorta, and it's really markedly, narrowed at this area.

After the stenosis, the left renal vein is dilated, and on this image you could see that, SMA takes off at the very sharp angle from the aorta.

And, there is also alias in detected within the area of stenosis in the left, renal vein.

So here we, again, we see that angle is measuring less than 17 degrees, and here you could see on Athena clip how the SMA takes off and near parallel, goes along, courses along the aorta.

And, on this CE eclipse, you can see the alias in within the narrowed portion of the left renal vein.

And this is a correspondent CTA again, the poor left renal vein is squashed in between the SMA and aorta.

Summary

As a summary, I, would like to say that Doppler ultrasound plays an important role in the evaluation and management of the aortic and mesenteric arterial disease.

It is essential in screening and follow up of AAA aids in detection of aortic and mesenteric dissection stenosis, occlusion, and pseudo aneurysm and aneurysm formation.

It's also demonstrates high accuracy for diagnosis of cardiac mesenteric ischemia and should be used as a first line modality for evaluation of nonspecific abdominal pain.

Thank you very much.