How To: Evaluation of Portal Hypertension - SD

Introduction to Abdominal Doppler Ultrasound of the Liver Vasculature

Hello, I'm Dr. Leslie Scout and I'm chief of ultrasound at Yale New Haven Hospital and a professor of diagnostic radiology at Yale University School of Medicine.

And I'm here today with Kim Bico, who is a wonderful sonographer and a very photogenic patient model here who is going to be acting as a patient.

And together we're going to describe to you the techniques of doing an abdominal doppler ultrasound with particular focus on evaluation of the liver vasculature.

Now, I think, and I think Kim will agree that this is probably the hardest of all of the ultrasound exams to do because there's so much anatomy and it is not necessarily in straight lines.

So it's often at very different angles.

And so technique here is as important as understanding the anatomy.

And the other thing that I want to say right from the beginning, that a lot of people when they start doing this exam think that they ought to be able to get all the information if they're good enough with a patient lying flat and just barely moving the transducer on the anterior abdominal wall.

And the fact of the matter is that you are looking at so many different vessels and they run in such different orientations from patient to patient that no sonographer, no matter how good they are, can do an adequate exam that way.

So you have to be prepared to understand that you need to use many different lines of sight with your transducer, that the patient actually has to be participatory in this exam, rolling in different positions.

And you really have to be prepared, as you've seen Kim just do here to move the transducer from the anterior abdominal wall to looking coronal from the lateral approach.

And the results that you get are going to be directly related to the effort that you put into this.

So with that as a background and some apologies to everybody watching because we do have a model here that really does have beautiful anatomy, and it won't always be this easy in your own practice.

We'll start by going over the anatomy and to point out some of the techniques and some of the acoustic windows that have worked best for us.

Liver Blood Supply and Portal Vein Anatomy

So what I like to do when I think about the liver is to follow the blood as it heads towards the liver.

And the liver itself is fed by two different vessels.

About 75% of the blood flow through the liver comes from the portal vein, and about 25% comes from the hepatic artery.

So let's start with the portal vein and follow that as it goes towards the liver.

Now the portal vein starts right below the head of the pancreas.

And it is fed by the splenic vein, which comes right underneath the pancreas as you see here, and the superior mesenteric vein.

And they meet in the portal confluence to form the main portal vein, which you can see here heading towards the liver.

So we're going to start off by looking at those structures.

So to start off, I want to find the splenic vein because that's the piece of anatomy that is easiest to find in all patients.

And the best way to look is with a transverse midline approach.

You place your probe just above the level of the aorta, which sits over the spine.

Sometimes you have to angle it a little bit to right or to the left as you see Kim doing here to lay out the splenic vein fully.

And sometimes you have to angle a little bit towards the feet or sometimes a little bit towards the head again to see it perfectly.

And you can see on the gray scale image that splenic vein and it goes, hugs just the underneath of the pancreas.

It crosses over the aorta and it joins the superior mesenteric vein to form the portal vein.

You all can notice on the monitor a little bit of echoes that are kind of moving in the portal confluence here.

And that is just slow flow in the portal vein, that vein dilates.

And so velocity will drop.

And so sometimes you can discriminate the rouleau formation of the red blood cells as they pass through it.

So let's just, we're gonna push a little bit harder, get a little bit of a better window here, and we'll point out some of the other anatomy that you're going to see as you're evaluating the portal system.

This echogenic curve, linear structure with shadowing is the spine on top of that.

The pulsating structure is the aorta.

From the aorta you can see a tubular structure here.

This will be the right renal artery that courses between the aorta and this other large structure that also pulsates little bit, not with cardiac pulsatility as much as it does with some respiration.

Maybe if you could take a deep breath, take a deep breath in and blow it out.

And you can see how that caliber of the inferior vena cava changes a little bit.

We have a little bit of artifact here as she just moves the transducer a little bit.

We can clean that up.

And that's the inferior vena cava coming off the aorta.

You can see the celiac axis and it comes up in a T shape as you see here.

This is a celiac axis with a branch to the patient's left is a splenic artery, and the branch to the patient's right is the common hepatic artery, which always travels above and slightly medial to the portal vein till it reaches the portal confluence.

So, and here is a good depiction of that right renal artery traveling between the inferior vena cava and the aorta between the main portal vein and the inferior vena cava runs only three possibilities.

Typically what you will see is the papillary process of the liver.

And occasionally you can see lymph nodes between the main portal vein and the inferior vena cava.

And if you ever see a vessel that courses between the main portal vein and inferior vena cava, this is gonna be a replaced right hepatic vein, which this patient does not have.

But that's a very common congenital anomaly.

So this is the anatomy.

And here, the way she's laid this out here, you can really see the blood coming this way from the splenic vein through the portal confluence.

And she's just angled her probe a little bit so that you can see the main portal vein entering the liver.

So once you know where you are, the next thing is to do some of the doppler evaluation.

Color Doppler Evaluation of the Portal System

And the first thing we're going to do is to put the color doppler on.

And that is going to show you these vessels in living color.

Now, we have used on this equipment a abdominal vascular preset, but you should be aware of some adjustments that you might have to make in order to optimize your image.

Now the first thing that I think that's the most important is to optimize the scale, which you can see here, the color bar.

And we'll show you that if we turn the scale way up so that these numbers increase that you actually don't see as much fill in of the vessels, but you get rid of some of that noise.

This is just some artifact from bowel gas.

If she turns that scale way down, you will be more sensitive to slow flow.

But you're going to get a lot of artifact, which is this flashing noise from the pulsations of the aorta and from breathing.

And while it is more sensitive to slow flow, and sometimes you need to have the scales relatively low to see flow within the venous structures, you have to titrate the scale so that it's kind of the three bears, the daddy bear, the mama bear and the baby bear.

You don't want it too high or too low.

It has to be in the middle just right.

So there isn't a lot of noise artifact.

And the, what you can see with a color, first of all, is whether or not a tubular structure is vascular.

And if it's vascular, of course it will fill in with color.

You also can tell direction of flow.

And the direction of flow is determined by how this color bar is set, such that what's ever on the top here in this case is red, indicates that flow is heading towards the transducer.

So in the splenic vein, which we can see on this image all the way from the tail of the pancreas to the portal confluence, the flow is red because the blood is traveling in this direction towards the transducer to the portal confluence.

And at that point, it looks as if it changes direction because it changes color and it goes right here.

There's an abrupt change in the splenic vein from red to blue.

Now that actually isn't a change in the way the blood is going towards the liver.

It just is a change of the angle.

It comes up here till it's about a straight angle.

And at this point the vessel curves a little, and the flow actually, although still going towards the liver, is going in an angle slightly angulated away from the transducer.

So still overall towards the liver, but the angle of the flow of blood has changed with relationship to the transducer box.

And that's why the color changes.

So it goes from red to blue just because of a difference in the angulation of the blood vessel, not because there's been any reversal of flow within the vessel because of that I think it is important to use a angle or to angle your transducer to make it clear which direction it's going in this.

So you can angle the transducer this way or that way, steer it so that it helps make it quite clear to you which way the blood is flowing in relationship to the transducer.

So we often start with it angled a little bit towards the patient's left as we look in the splenic vein.

And then as we look in the main portal vein, we'll angle a little bit towards the patient's right now, if there had been a true direction or change of blood flow at this point, you would have seen some increase in the intensity of the color.

You can't really determine velocity of flow directly on the color image, but the lighter the color is in general, the higher the velocity.

So if the blood flow had really changed in direction, you would see that it would wrap around becoming a white, turquoise to orange.

But when you see this black line here, as you see on the color bar, differentiating between the red and the blue, it's just due to the change in the relative angle to the transducer.

So here again, flow in the aorta that's pulsating.

Here's the flow in the celiac axis, which is that first branch coming up into the hepatic artery here, some flow in the inferior vena cava.

Spectral Doppler Tracing of the Portal System

And so the next thing that we're going to do is to get our pulse tracing or all spectral tracing.

And we'll start with obtaining a tracing in the splenic vein.

And if you want to measure the velocity, you need to angle correct, and that angle ought to be parallel to the lumen of the vessel.

And so you're going to have to tweak a little bit the angle of the transducer so that you really align that the vessel walls parallel to the cursor marker in the center of the vessel.

And once that's aligned, you're going to hit update and you'll get a spectral tracing.

And you analyze the spectral tracing much in the same way that you for direction of flow as you look at the color.

And we will just freeze this here so that we can talk about it.

So again, flow above the baseline, if it's positive here, is gonna be flow heading towards the transducer with flow below the baseline or where there are negative numbers being in a direction away from the transducer.

So again, blood in the splenic vein coming up towards the transducer.

So flow above the baseline.

Now, when you see this tracing, it is normal in the portal vein and splenic vein to see a little bit of respiratory variation such as you see in this patient, it is abnormal to have a completely flat wave form.

Because a flat wave form indicates portal hypertension.

Some people measure the difference or the amount of change in respiration from here to here.

And if there's less than a 20% change from inspiration to expiration, they consider that to be a very sensitive, a specific though not sensitive finding for an increased gradient in the liver consistent with portal hypertension.

Now, one of the things that you observed that Kim did as we started to obtain this tracing is that reflexly, she optimized it so that the tracing actually fills the screen.

And one thing that you can do, maybe you can turn that doppler scale down and show a very small tracing.

Here the scale is too high on the spectral doppler tracing.

And while you can see a little respiratory variation there, you really see very little flow at all.

So she's going to lower that scale, and you maximize it or lower it enough such that the tracing fills as much of the area as is allowable and you can lower the baseline as she just did, again, allowing you to decrease the scale further so that, again, the tracing fills the allotted space.

This isn't as important for venous structures as it is for arterial structures, but as a general rule of thumb, when you optimize your Doppler exam, you want the spectral tracing to fill the available space on the monitor.

So we obtain at least one tracing here, the splenic vein, and then we move on towards the main portal vein.

And we're going to go through a similar doppler approach.

She's gonna find the portal vein on the color image.

She's going to align the cursor there parallel to the walls of the portal vein.

And then we will obtain the doppler tracing, the spectral tracing.

Now it's going below the baseline because relative to the transducer, it's heading away from the transducer, even though it's still going towards the liver.

And again, she's going to optimize that wave form by decreasing the scale a little bit so that it fills in, and it magnifies the waveform.

And she will take one, capture one image there to represent the main portal vein.

Alright, now it's not enough just to get the main portal vein.

And again, another thing I should mention before we leave the main portal vein, some people measure the portal vein in inspiration and expiration the diameter of it.

And we can ask our model once we get organized, if you can take a deep breath in and hold it really, really deep, as deep as you possibly can and blow it all the way out.

A little hard to see deep, deep breath in, again, really deep and then blow it out.

We didn't see much change there.

But in some patients, there is a change in the diameter of the portal vein with inspiration and expiration.

It is more prominent actually in the SMV and in the splenic vein and in some locations where they evaluate patients a lot for cirrhosis, this is also something they can look at if the portal vein is greater than 13 millimeters at quiet respiration and 16 at deep inspiration, that's abnormal.

And if there isn't a three millimeter change with deep inspiration, that's considered abnormal as well.

Intrahepatic Portal Veins

So moving into the liver, we are going to want to take waveforms, the intrahepatic portal veins as well.

And as the portal vein enters the liver, it branches into the right lobe, or the right portal vein is what, and the left portal vein and the right portal vein will branch into the branch feeding the posterior segment, which is what we see here.

And that will have flow that is blue heading towards the liver capsule posteriorly and the anterior segment, which will be red coming more anteriorly as you see here.

So this is the anterior segment and the posterior segment.

Now, one of the things that you will notice right here is that despite the fact that we haven't changed our scale velocities at all, we see more flow in these little vessels than we do in the main portal vein right here.

And the reason that is, is that the portal vein is running almost 90 degrees or perpendicular to the transducer.

And so because of that, we don't see flow because at 90 degrees is when your doppler instrument is less sensitive to flow.

So when you see that you have a couple of options, you could turn the scale way up and see if that helps.

And it doesn't always.

You can choose the power doppler mode of imaging rather than the pulse doppler, whereas power directional color power, this machine has an upgrade and I didn't know anything about directional color power, but anyways, so it shows the direction as well as it will be more sensitive.

It's not as angle dependent, so it will pick up flow at 90 degrees.

And if you don't wanna have one of those fancy things, of course, the other thing that you can do is just change the direction that you're imaging so you are no longer at 90 degrees, and therefore more sensitive.

A third thing that you can do is to decrease the size of the color box because that will also increase your sensitivity to flow.

And you also always want to make sure that your depth is just at or just below the level that you are scanning.

So, I didn't mean to say depth, I meant to say focal zone.

And so again, you don't want it too low, but you don't want it too high.

You want it set just below the area that you're imaging.

So we would take a tracing in the posterior segment as well as anterior segment.

We're just going to do the posterior segment this time and again, go through the same techniques, maximizing the size of the tracing and making sure that the cross hair is parallel to the vessel wall.

And once we have finished with a right portal vein, we'll move on to looking at the left portal vein.

And that is often seen best coronally here is the main portal vein coming into the board of Hetus, and this is going to be the umbilical segment of the left portal vein, which runs in the echogenic falciform ligament here.

And it branches to a branch going to the lateral segment, and then one to the medial segment of the liver.

And again, you can see that with the color doppler and we'll obtain a tracing just showing how she's gonna move that cross hair to make sure it's, again, parallel to the vessel wall in the left portal vein.

And again, note that there's a little bit of transmitted cardiac pulsatility, but mostly what you're seeing is a respiratory variation.

So again, if you can just take a really deep breath in and you'll see flow will decrease, you let it out and the flow will come back.

And that's a normal finding that we'd expect to see.

So that's how you optimize your obtaining the doppler signal and looking at the portal vein.

And the easiest way to find it is to go transversely in the mid abdomen, starting with the splenic vein.

Superior Mesenteric Vein and Coronary Vein

Now, I mentioned that the portal vein is fed by both the splenic vein, which is quite easy to see, but also by the superior mesenteric vein.

And the way to find the superior mesenteric vein is to again, get on that transverse image, the splenic vein going into the portal confluence, and then turn 90 degrees so that you're parallel to the aorta and inferior vena cava and right above the inferior vena cava.

In that same plane, you're going to see the superior mesenteric vein and what courses between the superior mesenteric vein and the inferior vena cava is the uncinate process of the pancreas.

So if we go transversely, again, starting up where the confluence is and coming down towards the feet, you see the uncinate process of the pancreas right here.

You keep coming down, the superior mesenteric vein is right there, uncinate process between it and the cava.

So if she turns again in longitudinal plane, they're going to see that uncinate process traveling between the SMV and either the aorta or inferior vena cava posteriorly.

Now, the superior mesenteric vein is not probably critical to identify in all patients, except that it is a good marker of where the coronary vein is.

And so if you find the superior mesenteric vein and you look at it in the same projection in the region of the portal confluence, you'll see the little coronary vein rising, usually in that exact same obliquity.

So in the same plane as the superior mesenteric vein.

But running towards the head though the direction of blood flow, of course, normally would be from the head towards the portal confluence.

And finding this coronary vein is very, very important because it is the vein that feeds gastroesophageal varices.

So if a patient has portal hypertension and they're concerned about the possibility of gastroesophageal varices, this is the vein that you wanna look for because this is the one that feeds them.

And if you see flow going in the wrong direction, so towards the head instead of towards the feet, that is abnormal.

Or if this vein measures more than three to four millimeters in diameter, if that vein measures more than seven millimeters in diameter, a patient has a substantial risk of gastroesophageal bleeding.

And so that's why it's important to find that vein and be able to measure it.

And this one is perfectly normal in this case, at under two millimeters.

So those are the structures that we look at when we're trying to look at the portal venous system.

And here if she had a beautiful depiction there of the longitudinal view of the aorta with a branch vessels coming off, this is the celiac axis here and the superior mesenteric artery there.

Hepatic Artery Evaluation

Okay, so we go back to the portal confluence and the aorta, and we start looking for the hepatic artery.

And as I mentioned, and it's easy to see in this model, the hepatic artery arises from the celiac axis, which is the first anterior branch off of the aorta, usually comes in this T shape with the left branch to the splenic is a splenic artery, and the right branch going to the liver.

So this is the common hepatic artery, and we can obtain a doppler tracing right there because we see it beautifully.

And I generally, you can see this with color and again, see that pulsating flow and that helps.

But actually, in this particular model, and in many patients, you can do this perfectly well just with the gray scale imaging.

In fact, using the gray scale imaging sometimes is helpful because the frame rate is a little bit faster.

And so that you have better resolution when you turn the color on the frame rate slows down and that makes the image more susceptible to motion artifact from breathing.

So here's the hepatic artery, and she's going to again get the doppler tracing that cross hair parallel to the vessel wall.

And it's when you do the arterial signal that it's absolutely critical that you have that cross hair parallel to the wall.

Again, she's going to maximize that tracing so that it's as big as possible.

And normally the hepatic artery waveform has a very sharp upstroke as you see here, and she's a little pulsatile, so she bounces just a little bit there in the aorta.

So we may have more luck if we look closer in the port of heus.

So why don't we try that?

Normally it's hard to see the common hepatic artery, and we consider ourselves lucky if we see the hepatic artery in the region of the portal.

Remembering, as I said at the outset, it's going to be above and slightly medial to the portal vein.

And it typically runs between the portal vein and the common bile duct as you see there.

So if we put the color on that, sometimes we'll help identify for you what is the hepatic artery and what is the common bile duct.

And here is the common duct up on top in the hepatic artery right here.

Now, in this particular case, the hepatic artery and the portal vein, as in most normal patients, the flow's gonna be heading in both of them towards the liver and be in the same color.

It can be hard to differentiate them.

And one of the things that helps a lot is if you turn that scale way up and that will help separate them sometimes as separate structures.

I think I turned it up too far, Kim, you shouldn't let me touch this machine.

But here you can see it a little bit better and you can see that there's higher brightness because there's higher velocity in the hepatic artery.

So we can go ahead and take a doppler tracing there, and she's gonna have to drop the scale there.

And here is the typical wave form of the hepatic artery sharp upstroke and continuous forward diastolic flow, sharp upstroke and systole, and the diastolic flow there.

Maybe we'll get one more tracing and you'll can show them how to measure a resistive index.

Pulsatile, isn't she?

Let's try here.

Okay.

Perfect.

All right, breathe.

One of the problems that a nervous sonographer has often is asking a patient to take a deep breath.

And as they get focused on the machine, they forget to remind the patient to breathe.

So again, don't have your patient hold their breath for too long.

So to measure the resistive index, your machines will do this for you.

You measure peak systolic velocity and right here, end diastolic velocity and will calculate the resistive index, which in the hepatic artery is usually around 0.6, but certainly ought to be less than 0.7.

And so this is normal.

And to do a complete doppler examination, in addition to measuring the resistive index and getting away from the main hepatic artery, you need to do it from the right and left hepatic arteries as well.

So you just, we can show you with the left 'cause we're right here.

You just follow that left portal vein and up higher.

Once you see the artery surrounded by a liver, you can take a sampling there.

And she's gonna, again, change her angle here.

And even if you can't see the artery, you can just sample around on either side of the portal vein, and sometimes you will be able to identify it that way as well.

I think it's the angle.

There we go.

And she's gonna drop her scale there so that it, you can see it a little bit better.

And these vessels are so small that even if you have a small sample volume, often as you see here, you're going to see a little bit of portal venous flow in addition to the arterial flow.

So this is normal to see a little bit of portal vein flow.

In addition, 'cause the two are right next to each other.

You want to try one more time, see what we can do.

And again, the arterial and portal vein flow as well.

And particularly in a patient with a question of who's had a liver transplant, it's absolutely critical to get this inter parenchymal arterial flow as well as flow in the main hepatic artery in the porta.

So that's a nice example of flow in the left hepatic artery.

Hepatic Veins and Venous Drainage

So at this point, we found the flow towards the liver from both the portal vein and the hepatic artery.

And so the last thing that there is to do is to find the flow heading away from the liver, the venous drainage, which is through the hepatic veins.

And the easiest way to find them initially is generally from a transverse midline approach, sometimes angled a little bit towards the right shoulder.

And when you do that, you will be able to see the right middle and left hepatic veins joining here at the inferior vena cava.

And again, you're going to get, this is the right one here.

There's often some anomalies of the hepatic veins.

That's probably after the hepatic artery.

That's where the most anomalies occur.

And here's the right one.

So we'll get tracing there, right?

That's at 90 degrees and maybe a little hard.

There we go, maybe better.

And the waveform of the hepatic veins is very different from the waveform of the portal veins.

And it is normally a very pulsatile waveform with a slight reversal of flow as you see here, corresponding to atrial contraction.

And these have been described as the S V and D wave with the atrial contraction here.

And the atrial contraction is always in the opposite direction of the S wave.

Now, one of the things to remember, therefore is that some reversal of flow in the hepatic veins, normally they have flow going away from the liver, but a little reversal flow as you see here, a little change from blue to red, that red is normal and it's just the reversal flow during the time of the atrial kick.

So you have to remember to freeze your image when you see the blue because that's where the majority of blood through the cardiac cycle is going away from the liver.

But if you're not careful, you can actually freeze your image when the blood is red and it looks like flow is going towards the liver and that therefore it's reversed.

But that is not true.

That's a normal finding, and it just a slight reversal during the time of the atrial kick.

And we obtain a waveform just like we did for the right hepatic vein in the middle and left as well.

And maybe we can just show you the middle since it's right here and simple.

And again, it will be exactly the same.

And this really shows the different valleys beautifully with the atrial kick here, the S wave, the V wave and the D wave.

And again, that pulsatility is normal.

If you see a flat wave form in the hepatic veins, which is a wave form that looks a lot like the portal vein, that's a bad finding.

And that indicates that there's something obstructing the transmission of the cardiac pulsatility from the heart to the level that you're looking at.

And either there is external compression by a mass or there's a thrombus in the inferior vena cava or more distal hepatic vein.

So it is normal to see this pulsatile wave form in a flat wave form is indicative of either intrinsic disease or extrinsic compression.

Now you can also find the hepatic veins coronal.

And that's important because really the last thing that you do is to get waveform in the very inferior vena cava.

And that's often best done in a coronal view as you see here.

And you can see the hepatic veins joining the cava up by the diaphragm.

And we get a waveform just in the upper IVC as well.

And again, she changes her cross hairs.

And the waveform in the inferior vena cava ought to look like the waveform in the hepatic veins.

In other words, it has this pulsatile waveform with the two peaks as well as that reverse flow during the atrial kick.

So those are the veins that drain the liver, the right middle and left hepatic vein, which drain into the inferior vena cava.

Aorta and Additional Landmarks

And the very last thing that we do is to get a waveform from the aorta.

And the aorta, again, seen on the coronal image just medial or to the left of the inferior vena cava, or a little bit deeper as you see here.

And that should have, again, a very pulsatile wave form, sometimes without this much diastolic flow.

But again, always a very sharp systolic upstroke.

And not that the aorta is really part of the liver, but it is a good thing to look at because of course it feeds the hepatic artery via the celiac axis.

But you ought to get used to looking for the aorta because if you can find the aorta and you can find where the aorta goes through the diaphragm.

And here's the diaphragm here, this echogenic line, this is the area where you're going to see gastroesophageal varices right around the aorta between the aorta and the stomach.

And those are things that you want to look for in a patient whom you're suspicious that they may have portal hypertension and might be bleeding for varices.

So it should be part of your routine exam, and it serves as a landmark for a potential significant pathology, namely gastroesophageal varices.

Patient Positioning and Final Tips

So that's kind of a summation of how I watch an excellent sonographer to an examination of the liver vasculature.

So I don't know, Kim, if you have other suggestions or other tips.

I think that while we have such a wonderful model here, we will show you just a couple of other positions.

We didn't have to use them in her, but notice that while we did a lot of the exam from the anterior abdominal approach in the midline, we do come in sometimes coronal.

And while in her it worked for her to be flat, it often is very helpful to have the patient turn up, put their left side down.

And here you can see a beautiful depiction of the inferior vena cava here.

And here you see a gorgeous look at that main portal vein branching into the right here and the left portal vein as well.

And here are the hepatic veins.

Now another thing that can be helpful is how you differentiate on an image like this, which is a portal vein and which is hepatic vein.

The hepatic veins don't have much around them, and so they have a wall that you really can't see.

So you just see the blackness in the vessel, and then it goes straight into the liver parenchyma, the portal veins run of course in the portal triad, and the bile ducts are there, the hepatic artery.

And so they're surrounded by a very echogenic wall like you see here.

So you can differentiate a little tiny portal vein like up here from a hepatic vein here.

This one's a hepatic vein, partly by the direction that it flows down for the cava, but also by the echogenicity of the wall.

So it's the portal structures that are echogenic.

And here this very echogenic structure, of course, is the diaphragm.

And so here's the cava, the caudate lobe, and the main portal vein here.

So again, one position, one acoustic window.

One way of looking isn't going to work in all patients, and in most patients you really have to look from multiple planes in order to get a complete examination.

And she's showing again how very often with a patient in that position and you aim up towards the right shoulder.

You can see the hepatic veins well in cava.

And here's the portal vein up here.

Thank you very much.

Thank you.