Optimizing the Vascular US Exam: Pearls and Pitfalls - HD

Pearls and Pitfalls in the Vascular Exam

Hi, I'm Michelle Robin from the University of Alabama at Birmingham.

Today we're gonna talk about pearls and pitfalls in the vascular exam.

Now ultrasound imaging is enough for a diagnosis.

The question here is, is there a renal vein thrombus?

We clearly see there's a renal vein thrombus.

We don't have to go to any other imaging.

You can see this in the transverse plane as well.

There is a large renal vein thrombus that's flapping here.

I'm worried that it's gonna break off and go into the lungs.

Ultrasound today, a lot of departments are not using ultrasound to the fullest capability.

It's a great bread and butter examination, but we have to do it well or we're not gonna get a referral a second time.

Ultrasound can replace CT and MRI and angiography in many, many cases, and economics, particularly with all the changes going on in Washington, will probably force this shift.

We don't spend enough time, however, optimizing images to improve our diagnostic capability.

You need to optimize the images to get the most outta the equipment, to be able to figure out exactly what the clinician wants to know and to make that diagnosis with ultrasound rather than sending them on to other tests that possibly have radiation or are much more expensive.

Nearly all specialties are using ultrasound and often with inadequate training.

We do have an article called ultrasound Quality and Efficiency, how to Make your Practice Flourish.

And it talks about how to optimize and how to optimize your ultrasound laboratory and to make your practice have fantastic diagnoses and fantastic images.

So again, ultrasound today is not just a screening tool, it's a final diagnosis, particularly in the vascular arena.

And if we don't know the answer, if we can't figure it out and we can't infer it based on what we found, then CT MRI and Angio will be used.

And that's what we have all those other tests for.

Optimizing the Ultrasound Scanner

So what we're gonna talk about today is the ultrasound scanner.

I want you to know all the buttons and if you feel uncomfortable when I say, do you know all the buttons and you need to do some homework, our sonographers are expected to know all the buttons.

That's what they're there for.

We've got these premium scanners that can do all these different things and yet we're just treating it like a handheld scanner, which are good, don't get me wrong.

But there's a lot of other things that we can do with these higher, more premium scanners.

So first of all, we wanna optimize the imaging.

And the way we do that is a very programmed way.

We start with a gray scale and then we do color doppler and then we optimize spectral doppler.

So you can't start with spectral doppler and figure that everything is gonna be perfect.

You've gotta start in this order if you're gonna use color and spectral doppler.

Understanding the Clinical Question

The other things you need to know are what is the clinical question being asked?

That is the most important thing of any ultrasound indeed of any other ultrasound or any modality that we do in radiology.

Why are we doing this?

Because we might not be able to answer that question with ultrasound and then we should refer to a different test.

So we also need to know what the normal anatomy is in the relevant anatomy, including waveforms.

If you don't know the normal, how are you gonna tell abnormal?

And then what are the diagnostic possibilities given the clinical question and what the images show.

We all know what the differential diagnosis is going to be for any particular situation.

And the ultrasound and the clinical information will help you figure out which to put first in that differential.

Optimizing Gray Scale Imaging

So the first thing that we wanna do is optimize the gray scale imaging.

And the first part of that is to choose the appropriate transducer.

I always try to use the highest frequency that will allow adequate penetration.

And I love it when the stenographer shows me a transduced an image from a transducer that maybe is too high, it doesn't really work.

They take an image though, and then they move on to the next lower frequency transducer that allows adequate penetration.

So I know they tried to get really great images, couldn't quite get it because of the size of the patient and had to go to a lower frequency with that same first transducer.

Though you may need to decrease the frequency because sometimes you can shift frequencies in a given transducer.

So you may need to decrease the frequency to get increased gray scale and color doppler penetration.

So once you get past the gray scale, you may either have to decrease the frequency to optimize your doppler imaging or to go to a different transducer altogether.

So if you can't optimize, change the transducer and it's okay to use multiple transducers for an exam.

Now, four or five maybe it's a lot, but sometimes in difficult cases we actually try four or five transducers.

'cause if we can get the answer, the patient doesn't have to go on to other imaging.

So for example, in an arm DVT where there's a clinical question of an acute thrombus, we might use a 15 megahertz taki stick for arm veins, a nine megahertz linear for the subclavian veins.

And then if we want to see the central veins, because there's an abnormality in the waveform of the subclavian or internal jugular veins, we may use a baby head probe in the sub, in the supra sternal notch to look for central veins.

So the other thing you need to do once you've picked the transducer and it can image what you want to image is to determine which part of the body do you need to image, do you need to image the near field?

If you need to see that, you're probably gonna need to use a linear for small parts of musculoskeletal and a curved or a sector array for general abdomen.

And then if you still are having difficulty, you need to use harmonic imaging in the other specialized new tech techniques that are available.

So for example, this is a patient that has a pretty stenotic liver.

It's quite genic.

They are fairly thick as well, and we're just not penetrating.

You can see some specular reverberation off the diaphragm, but really we're not getting any diagnostic information about the liver probably coddle or posterior tube, about eight or so centimeters.

Well, we put on a different transducer or we just changed the penetration mode on this transducer and now we're able to see a lot better.

We're still not seeing it well, but we're seeing it a lot better.

I can see vessels down further into the liver and I gotta, I have a better idea of whether there's gross masses of here, here or not.

Of course, I can't completely exclude masses on this study, but I can see the liver a little bit better than I can.

Before this is a patient that has cirrhosis.

His liver is obviously cirrhotic and he's got portal vein thrombus.

Well, when we have portal vein thrombus, we think of a couple things.

First of all, in a liver that's cirrhotic, we think that there's a hepatocellular carcinoma.

Second thing I wanna know is, is there tumor thrombus or is this plan thrombus?

And so you can look for the tumor that we know is probably gonna be there.

And I don't really see it.

We had to turn CP on.

When I get to CPI know I'm having trouble, but there is a subtle lesion there and I can see it better with color coding.

So if you're having trouble seeing a lesion or discriminating it from the background, add some color coding that will help you.

And again, that's a button you might not use very often, but please learn it.

This is another patient that this is a carotid.

We've got a linear study and look, we are imaging into his neck vertebrae.

Do I need to know the image, the information in the neck vertebra for a carotid ultrasound?

Certainly not.

So I need to decrease my depth and completely get rid of all these wasted pixels and optimize my imaging.

Now I'm able to see the carotid in a lot more detail because I'm devoting a lot more pixels to it and I can see that there is some plaque and possibly some calcification here.

So the other thing we need to do is to optimize the TGC, and that's the time gain compensation curve.

Some scanners have an automatic setting to give you a starting point.

When I started doing this, when they came out, I thought, oh, I don't wanna use that.

I can get the pictures perfect without them.

And it's true, I can, but it's gonna take me longer.

So use 'em just as a starting point and then alter it as you wish thereafter.

So when you're gonna use the TGC curve and you're just coming on that scanner, somebody else has used it before, you start with the overall image gain in the middle and put that TGC, the trim pots in the middle as well.

And once you've balanced it, then you can start moving the image gain up or down.

Then you need to put the focal zone at or just above or below where you are looking.

So some scanners, it seems like you get a little bit better focus on the area of interest if you put the scanner or the focal zone above it, some below it.

Now some manufacturers are saying, we don't need to even focus it.

We're focused throughout the field.

You just need to learn where your manufacturer says is optimum for a focal zone if it's available.

And again, don't waste pixels.

Accurate Measurements in Gray Scale

The other thing you need to do is you need to measure accurately and correctly, and this is best done in gray scale.

So for example, this is aaa and the sonographer measured the inner diameter of the triple A.

That is not the correct measurement.

If you only measure the inner diameter, we are only as good as angiography and angiography can grossly misrepresent the lumen because they're only looking at the lumen of an aorta.

So you may have a two centimeter lumen and a five centimeter abdominal aortic aneurysm.

This is not such a gross case, is that, but you need to measure the outside of this lumen.

So outer diameter for aaa.

And this is something that we kinda creep in somehow, and I'm not quite sure why.

Then vein walls, we look at the lumen.

So it is kind of confusing.

We have to know when to measure and what to measure.

Here.

This vein wall is over measured and we want to know the lumen.

So right now, this is a thickened vein wall and we are measuring the outside.

So this patient may be deemed perfect for a hemodialysis fistula, when in fact that inner lumen is too small by criteria.

So inner diameter for vein walls, I've put this circle, this thick circle along the vein walls to show this is where you should be measuring is the inner lumen.

This is another patient whose vein wall thickening was recognized by the sonographer.

You can see a very thick wall and we're measuring the inter lumen.

And this is too small a vein to use for the purpose that we were evaluating it for.

And that is another depiction of the vein wall thickening.

So you need to know what and how to measure.

Very important.

And that's one of the interesting and really fun things about ultrasound is that we have to deal with so many different specialties and know what they need and what they want.

Optimizing Color Imaging

The next thing after you've optimized the gray scale imaging is to optimize the color imaging.

Now color was a huge revolution, but you need to understand the pitfalls.

So first, again, optimize the gray scale.

And then in radiology we typically set red, the red color towards the transducer as the radiology standard.

You will not find that to be true in some cardiology labs and in most vascular surgery labs, they always have red B, the artery and blue v be the vein.

The reason why we set red is towards the transducer is that's a standard.

So then for every image, we don't have to evaluate whether or not the assessment by the sonographer is correct in terms of blood flow direction.

And we don't, it doesn't take quite as much time to evaluate every image to see whether that blood flow is traveling in the correct direction or in the reverse direction, which would be abnormal.

And again, one of the things that you need to do is to check all cystic structures for flow.

And I'll show you some examples of that.

This is a patient who we were supposed to rule out hydro nephrosis, and we probably do this, I don't know, 20 times a day.

And so here's an echogenic kidney and yep, it looks like typical hydronephrosis.

The all these cystic structures line up.

It's a little bit odd, but it looks like it's hydronephrosis.

Well, when we put the color on, all of a sudden we see all kinds of color here, all kinds of vibrating, and there's color where we don't expect it.

There's no, it's in the cystic area and then it's outside where we expect solid tissue to be.

So most of you will have recognized that this is almost certain to be an arterial venous fistula.

And this was a patient that had had a native kidney biopsy and had both a pseudo aneurysm right here and a fistula after biopsy.

And so we're verifying flow in the structure.

And then once we've shown all this tissue vibration artifact, which puts color pixels in soft tissue where there are no vessels, then you increase the color scale to try not to have so much bleed of the color over the actual cystic structures.

And so you can see the anatomy a little bit better.

Well this is probably the prettiest gray scale image I own and I just love this one.

It's a mass after a brachial artery stick is what the requisition said.

And indeed it is a mass, it's a pseudo aneurysm.

You can see it slowly pulsing there and it's beautiful with a ru low flow.

But where is the neck of that pseudo aneurysm?

Where exactly in the vessel?

And do I wanna even think about putting thrombin in it?

Well, no, I actually don't wanna put thrombin in it, but by the way, harmonics does aid in seeing the ru low.

This image was taken with harmonics, but only with color can I see the little jet from the neck and I can evaluate it.

And this is not a huge rent in the vessel.

So when the surgeon goes in and ties this off, they're just gonna find a tiny little neck at the place of needle puncture.

They're not gonna find a huge rent.

So when we're gonna optimize color imaging, we should optimize that imaging in a normal portion of the vessel because then we're gonna be able to use elevation in peak sto velocity as a screen for areas of abnormality in the vessel.

So in order to optimize in a normal portion of the vessel, you turn up the color gain until you see random color pixels outside of the lumen and in the soft tissue, and then turn it down until they just go away.

And then your color gain is optimized.

Then you need to decrease the color scale, the pulse repetition frequency until you see color only in the vessel.

So you don't have that bleeding of the color pixels into the intima media and adventitia of the vessel or even beyond.

You may need to increase the wall filter if there's high velocity flow so that you have less clutter.

It takes out the low velocity signals and you end up with a lot better image if it's a high velocity flow, such as in the aorta.

The other thing, and so this is an example here is a carotid and can I measure this?

Can I tell you what the lumen diameter is?

No, I can't.

This is color bleed.

But then when I decrease the, or increase the scale, now I can see the lumen, I can see the intima, and I do not have the low velocities because I've got the high wall filter on.

I'm not completely filling it, but I am able to see the lumen.

And this is about the technique that you should use for carotids because you don't want to overwrite the wall because then you could miss significant plaque, even if it's hypo coic and significant stenosis.

All right?

So when you wanna measure, take the color off.

Much better resolution in gray scale because the scanner has to do two separate things.

It has to look for color and it also has to do gray scale imaging.

And so you end up without quite as good an image with color on.

All right, this is a patient with a failing hemolysis fistula.

And this is a beautiful, very decent looking size vein.

I mean, it's not the world's greatest fistula.

It looks like it might be narrow, but when you take the color off, I mean it looks okay.

When you take the cover off, you can't even see a lumen here, the color off, you can't even see the lumen.

So clearly this is a problematic fistula and this is a stenosis here.

So the color is overriding the wall.

So if we would have only used color, we would've grossly overestimated the lumen diameter.

This is that same fistula.

It looks pretty good with the color on, but then when you take the color off, there's a stenosis there and that's the main problem.

That's why this fistula is not developing.

All right, so the next thing you wanna do is to optimize, in optimizing color imaging is to use the normal setting as a screen.

And then once you go up that vessel or down that vessel, you'll be if you see any aliasing, there'll be potentially abnormal flow.

And then that's exactly where you look with peak systolic velocity and spectral doppler to determine whether or not there's some significant narrowing.

Now remember that you won't see color flow if vessel is perpendicular to the transducer.

And that's because the cosine of theta, which is 90 degrees if you're perpendicular, is zero in the Doppler equation.

And we're not gonna go into the Doppler equation anymore than that.

But to tell you that if your transducer is perpendicular to the vessel, you may not see any flow and there's plenty of flow there.

So you need to steer the color box to less than 60 degrees, and that's our normal standard.

If we have less than 60 degrees, we can get an fairly accurate PTO velocity.

And if you can't steer that color box, you may need to heel toe the probes or rock it back and forth until you can get an angle that's less than 60 degrees.

This is a patient that has asymmetric distal common carotid PTO velocities.

The distal common carotid on the right is 30, and on the left is 63.

Well, which is abnormal.

Well, we know that the PTO velocities should not be 30, so we know that side is abnormal and we think it's gotta be from a stenosis.

What else would it be from in the carotid?

Well, I can't tell you if there's a stenosis or not there based on gray scale because the plaque is shadowing me out.

So basically I can't see the stenosis.

So what I have to do is to put color on.

Well, when I put color on actually in this case and move it around a little bit, I'm not completely shadowed out and I am able to see the severe carotid bulb stenosis.

I have aliasing there and I'm at the maximum peak toto velocity.

So this is very high peak toto velocity.

It's 550.

So I think that's consistent with the stenosis, clearly by criteria over 70%, but really visually closer to 90%.

All right, so this patient has proximal ICA spectral broadening.

So we're gonna go distal to a stenosis, which is more cranial in the ICA and we're gonna see spectral broadening.

And in the distal ICA, this stenosis is so tight that we're actually seeing a frank TARDIS parvis, which is a delayed upstroke and a slow PS dog or a low PS dog velocity.

So that's a classic TARDIS pars pattern post stenosis.

Maximizing Color for Low Flow

All right, next topic is how to maximize color for low flow.

There are a lot of pitfalls in color doppler imaging, and this is one of the biggest ones that you can fall into.

Again, you need to address your color gain setting, turn the color gain up until you can just see random color pixels and then turn it down until they just go away.

You need to decrease the color, scale the PRF and then decrease the wall filter to a low flow state.

And some scanners do have a composite low flow state.

Well, they will change multiple things and they may decrease the rep, the frequency as well so that you make sure that you're detecting as much flow as you possibly can.

So you may need to change to power doppler, which is relatively angle independent that displays blood flow amplitude, but that's in limited use in areas with significant motion In the deep abdomen.

You need to increase your gray scale penetration because if you can't see it, you're probably not gonna be able to get color in it.

Decrease the frequency, change the wall filter, decrease it.

And then if all else fails, go ahead and switch to a lower frequency transducer.

If you have one in a superficial vessel or organ, you may need to switch to a higher frequency transducer.

You need to play with it and try both a higher and a lower frequency transducer to see if you can visualize it adequately.

So this is a patient who has portal vein thrombus and what we're seeing is the arterial flow, correct?

Well, maybe not.

This is a cirrhotic patient and this cirrhotic patient has significant arterial flow because they are cirrhotic and the portal vein flow is slow.

So what we need to do, color scale's 15 here, if we drop the color scale Down to seven, now all of a sudden we're showing the flow in the portal vein.

We're seeing a little bit in the arterial side, but we're able to show that there is flow there isn't thrombus here.

So very important to know how to do this and to look for it.

Just because it's black or you're not seeing flu initially doesn't mean that it's thromboses.

This is a patient that we had relatively recently.

It was on call, it was a real busy day on a Saturday, and the patient was status post to DNC and she still had bleeding.

So the clinical question is, does she just have blood in her endometrial cavity or does she have retained products of conception?

Because if she has retained products of conception, she's gonna need a DNC.

So the endometrium is sickened and we can see everything beautifully.

In fact, we can see flow in the middle of the right ovary.

So we're all set up, we're seeing everything wonderfully.

And this sonographer that was on with me that day put on color and I'm not seeing any flow.

And just to put icing on the cake, just to be sure, because they knew that I was on, they were showing off a little bit and said, you know what?

I wanna be sure that she's happy with these gorgeous images I'm taking.

And they put power doppler on and there's no flow.

Well, there's a problem though.

I looked at it and said, okay, these images are great, but your composite setting for the wall filter and all the low flow states is medium.

And I'm not sure if we put it on a low flow composite state, perhaps we're gonna see flow.

So we went back in, had to put the transducer back in and it was worth it because what we found when we switched to a low wall filter is we saw definite flow in the endometrial cavity.

And we verified that always verify everything with spectral.

We verified that with spectral and this patient did have to go to A DNC and retained products of conception was verified then.

And we completely 180 changed the diagnosis in a matter of several minutes.

So very important to understand how to optimize your imaging for a low flow state, a medium or a high flow state.

The Twinkle Artifact

Let's talk about the twinkle artifact.

That is the interaction of the ultrasound beam with rough, highly reflective surfaces and it's generated by intrinsic scanner noise and some says phase or clock jitter.

There are other technical explanations for this, but this is a good one.

If you and you want this, this is a desired artifact.

There are some artifacts that are good.

And the way you look for this artifact is to increase the color doppler scale just above visualization of color in normal vessels and then turn off harmonic imaging and all those other advanced features.

And you will see this artifact if you have a stone and it is a random mix of colors posterior to the calcification.

You may see when the acoustic shadowing from the calcification is not pronounced.

So sometimes you can see twinkle artifact and you can't really see shadowing from the stone.

And we use this every day to improve detection of small renal stones.

And it's a very common study now for US bread and butter study on the days when there's renal clinics to follow overall stone burden.

'cause we certainly don't need to do ionizing radiation CT scans to follow stone burdens.

And we're commonly doing this now after lithotripsy and other manipulations.

And remember, you're not gonna find any flow at spectral doppler.

So if you ever get confused and you think that this twinkle artifact is actually flow in a tumor or some kind of funky looking abnormality, you're never gonna be able to see flow at spectral doppler.

So this is a patient with right flank pain and the CT three weeks ago showed a distal two millimeter stone.

Well, have they passed it?

They didn't know.

They didn't think so, but they weren't sure.

We don't see hydro now.

So that's good evidence that they've passed it, correct.

Well, maybe not, but maybe it's a non obstructing stone.

Two millimeters, that's not huge.

There is a little bit of fluid in the renal pelvis, so maybe that stone is still there.

How do we tell the bladder wasn't very full?

And rather than wait for her to fill her bladder, which we easily could have done 'cause she was an outpatient, came in through the ER and we went to endo vaginal scan as instead.

And endo vaginal scanning is very nice for looking at the distal ureters.

And here is the stone.

My sonographer was upset because I found it.

But with ev you can see a lot better the trigone of the bladder and the distal ureters.

And here's the stone and here is the twinkle.

And again, if your bladder's not full, you're just not gonna be able to see this.

And then this is the icing on the cake.

We saw the ureteral jet and that shows that's stone is not obstructing, so that stone is still stuck there.

And for three weeks they're gonna have to probably go in and get it.

Our urologists now use the presence or absence of ureteral jets to determine non obstructing versus obstructing stones.

And this is a very useful phenomena for them.

Optimizing Spectral Doppler

All right, moving on to spectral doppler.

You can't let the waveform get too small because you can't evaluate it, so you need to adjust the scale.

So the waveform films about two thirds of the box without aliasing and then adjust the gain so you don't have artificial fill in of the spectral waveform because if you have a filled in waveform that would suggest disturbed or turbulent flow and you don't always have that, sometimes your gain is just not correctly set.

So this isn't a patient with right renal artery stenosis and we've got an echogenic kidney, it's smaller than the left side and we can see clearly that there's aliasing of this kidney off the aorta or off the aliasing of the main renal artery off the aorta.

But we always verify everything and we get a peak systolic velocity of 3.2 and we could quit there because that is a definite abnormal peak systolic velocity, but it's not a very good waveform.

And so what we did was actually open that color gate up a little bit so that we can see the vessel a little bit better, we're encompassing the vessel better, and it was and we were able to get more signal into that color gate.

And so now we're clear it's 3.72 and that's a bonafide renal artery stenosis and an abnormally elevated PTO velocity.

In renal artery stenosis, we always evaluate the main renal artery and the intrarenal wave forms.

Don't use the liver or spleen as a window because then you're coming in more perpendicular to the vessels and you're not gonna be able to detect them as well.

So use the flank approach for intrarenal evaluation of the arteries.

And that improves the angle of intonation of the segmental arteries because we need to look for early systolic peaks.

So when we're looking at a vessel, we usually evaluate vessels with spectral wave farm proximal to distal.

So we assess the waveform.

Is it normal?

So again, you need to know what normal is, what a normal peak cysto velocity is.

Is it symmetric bilaterally?

Most of the things we have, we have to of, and this is a case where sometimes we might find something that we're not expecting.

This patient had a brewery status post cardiac cath.

I don't see anything.

Looks good.

No DVT, no fluid collection, of course, we're really looking for a fistula here.

And this patient has marked tissue vibration artifact like we saw previously.

Now, as soon as you see this, you've got to think that there's a fistula.

We didn't see a DVT.

And when we put doppler in the femoral vein, we saw a right superficial femoral artery to femoral vein fistula.

So that's nicely shown.

Sometimes we don't know that there's a history of catheterization.

We had a this patient was a leg swelling patient rule out DVT, just the typical one that we do, I don't know, 30 a day, 20 a day, something like that.

And this patient, when they stopped, what we actually had them stop breathing, the higher p sto velocity of the arterial flow actually kind of shined through the fact that the vein forward flow had stopped, but the artery was still pulsating away.

And this patient is a very abnormal waveform, clearly 'cause we're in the comm femoral vein.

And that patient had an arterial venous fistula that was not suspected.

Here's this patient was interesting too because they really didn't have any tissue artifact.

Remember when I showed you that they, I mean, it looked just like a pretty normal DVT, but then we had this very abnormal waveform.

Well, when we re position the closer to where the fistula is, we see there is an arterial signal and this is a an image in the transverse plane of that arterial venous fistula.

And when you val Salva, you can stop the forward flow of the venous blood.

But again, the arterial flow is higher POC velocity and so you may still see arterial pulsation.

Case Example: Carotid Evaluation

All right, this is the last case where we wrap everything up.

We're gonna put everything together.

65-year-old male with carotid brewery.

So this examination is depicted as the sonographer performed it.

Here's the right ICA proximally.

It looks pretty good.

Really not much plaque.

The ICA looks good.

PTO velocity one 11, there's a little bit of diastolic, there is some diastolic flow, which is normal.

Don't see any stenosis.

And then ECA looks good, no stenosis on gray scale.

But then we put color on.

And wait a minute, I don't even see any color, I don't see even any flow in what we think is the ECA.

All right, so now it's time to reevaluate where's that stenosis, which vessel is stenotic?

And that's very important.

When we put color on, we see that there's a little bit of flow, a trickle of flow in that vessel, a high grade stenosis.

And when we drop a spectral doppler there, we've got a peak cysto velocity of 145.

So we're still thinking that we're in the ECA, but there's a lot of diastolic flow.

So how do you determine which is the ECA and which is the ICA?

You use your anatomy, your knowledge of anatomy and the temporal tap.

And this is a pretty weak temporal tap.

So we need to reevaluate here.

So the temporal tap is always seen in the external carotid artery.

So this is a patient, this.

So we're going back now to look at what we thought was the ICA and we get a strong temporal tap here, and we're going back to look what we thought was the ECA and we're not getting a very good temporal tap.

So clearly this is the e, this is the ECA, this is the ICA.

There's a very significant ICA stenosis here, and I will refer you to some of our articles on temporal tap imaging.

To again, you have to know the anatomy and know all the different things that you can use to help you in diagnosis, which artery you're in.

And then use all the tricks at your disposal to try to make a diagnosis without having to move on to additional imaging.

Summary

So in summary, this has been a whirlwind tour through vascular ultrasound, and I would like you to learn all of the buttons, or at least nearly all of them.

If you know how to optimize the images, the your image quality will improve and the sonographers will take great pride in the images that depict advanced pathology because those people are walking around out there.

And your diagnostic capability and ultrasound volume will grow.

And I'd like to acknowledge and thank the excellent sonographers and radiologists at UAB hospital, the Kirk Clinic and Highlands Hospital, for their dedication to patients and advanced ultrasound imaging.

Thank you.