Tips & Tricks - SD

Introduction and Background

My name is Han Peter Esco.

I am an internist,

and I started to do ultrasound in the year 1982.

And with contrast agents,

I did the first studies in 1996.

At that time, we had LEVU as the agent,

that was followed by a second generation agent, some

of you in 2001.

So I'm now head of the central ultrasound department in

the Silva Hospital in Hanover, Germany.

And we are performing a lot of

ultrasound studies,

roundabout 17,000 a year.

And the major interest that we have is of course,

interventions, contrast agents.

So we are performing all kind of

studies except cardiac examinations

and O OB GYN examinations.

Now, this time I'm going to talk about tips

and tricks when using ultrasound contrast agent agents.

Pre-Examination Checks and Contraindications

And before we start with our extermination,

there are a few questions to be answered.

Number one is, can

seals contribute to the clinical problem?

And second, are there any contraindications like unstable

coronary heart disease, severe pulmonary hypertension,

pregnancy, and the use of contrast agent in children

is not approved in Europe or Asia.

But in case you think it is justified,

then you have to ask, of course, the parents

and they have to sign an agreement on that.

Are there any cardiac diseases?

Because this has an influence on the contrast kinetics,

especially right heart failure, either aortic valve stenosis

or insufficiencies valve prothesis or arrhythmia.

Written consent is needed in Germany,

not in all European countries,

but in some, do you have a

safe venous access check, the venous line

that has been placed before on the ward,

sometimes they're occluded

or are not ready to be used

prepared for emergency cases.

And aphy like to eat reactions are very seldom,

but in case they appear, you have to be prepared for that.

Previous imaging studies like CT MRI

or PET should be reviewed

previous to your study.

The needle size and needle placement, we avoid

small needle sizes and hand veins.

And last not least, the dose, we use doses between 0.5

and 2.4 ml vu as bolus.

This is a preferred mode followed

by a tele ML saline flash.

Venous Access and Patient Preparation

Now, in case you have a big patient,

do you have any chance to image

one

of the abdominal organs and you should check

before in gray scale.

And if you have a acceptable gray scale image quality,

then you are fine.

Also with contrast, venous access, as I just

was telling, is an important issue.

Of course, you have to look

for a venous access if there is not a needle placed

intravenously before you have to do it yourself.

And in case of an arm like this,

you can imagine it's not that easy to palpate a vein

and to puncture this vein.

So in these cases, we use ultrasound high frequency probe

to find a appropriate vein,

and we can place the needle then

with ultrasound guidance.

And when you have placed the needle, then look

that the contrast agent is going directly into the vein

and the saline flash as it's shown here in the

photo, should be administered directly afterwards.

Device and Dose Recommendations

Those recommendations, that depends

of course on the ultrasound device that you are using.

The transducer frequency

and the type of transfuser that you use

for the contrast ultrasound study,

avoid oversaturation,

and that is visible during the arterial phase.

A too high dose of contrast agent will lead to an

over saturation of the major vessels

at low doses.

The vessels will be displayed without any ballooning

artifacts during the anterior phase and with higher doses.

On the other hand, the late phase will be lengthened.

The bigger the patient and the more distal the ROI is

located, the higher the dose has to be.

Of course, within limits, I would not go beyond the

two time dose that you normally use.

And normally we are using for liver studies between one

and 1.2 ml, so I would not go beyond two

to 2.4 ml vu.

Ultrasound contrast agent will not compensate a loss

of tissue information due

to attenuation like in severe fatty liver disease.

If lesions cannot be imaged in tissue harmonic mode seals will also not be diagnostic.

Special Application: Fistula Imaging

A few drops of contrast agents dissolved in saline are

sufficient for imaging of fistula or intra cavitary imaging.

As you can see it here, this is a patient

with a Crohn's disease and a 20-year-old male.

And on the skin you can see an ulceration.

And if you puncture this with a needle, then you give the contrast, in this case,

only two drops in 20 ml

and you can follow the fistula being filled.

And now you can see

that the contrast agent is now entering the intestine.

And this is the second shot that we did.

And again, you can see the network of the fistulas

that connect different parts of the intestine,

and you can clearly differentiate the air

that is within the intestine from the contrast agent.

Mechanical Index (MI) Settings

The right eye number of course, the right

and eye number depends on the ultrasound device

that you have and the probes frequency.

And that might differ even

between the same machines of the same company.

The lower the MI number, the less enhancement you will

you can expect in the far field

and the less bubble destruction in the near field.

But the higher the MI number,

the higher the enhancement level in the far field,

but more bubbles will be destroyed within the near field.

Factors Affecting Contrast Kinetics

Physiological Differences

Regarding the kinetics of contrast agents,

there are some physiological differences as we think.

Number one is the age, the younger the patients,

the longer the enhancement will last.

So we have a longer late face in hospital

of the liver in young patients.

And not so long in older patients.

Breathing, of course, influences the kinetics.

For example, if you see a lesion and let the patient inhale

and ask the patient to hold breast, most

of the patients start then pressing.

And this will cause a delay in the wash in phase,

so the contrast agent will arrive later.

And not so many bubbles will enter the

circulation of the liver.

When holding breath

and pressing very strongly shunts, like in cirrhosis

or ulcer disease, means that we have

very often less parenchymal enhancement.

We think that gender, the last meal time during the day

and especially medication,

will also influence the contrast kinetics.

But that has so far not been studied.

Technical Reasons

Some technical reasons that influence the kinetics

or that influence the measurements

that you will perform during your studies

is the venous line placement.

So if you have a central venous access,

then the contrast agent will come up very quickly.

Phase inversion amplitude mode that also may influence

the kinetics.

Late contrast arrival, yes, that is a can be seen

of course during holding breath

and pressing cardiac diseases.

And pulmonary diseases will lead

to a late contrast arrival.

The patient's position also plays a role,

so avoid the pressure on distal veins.

I will show you shortly. Subclavian veins thrombosis

or arterial stenosis like thoracic outlet syndrome

and early bubble destruction due to high pressure,

like in some venous ports can be expected.

The early arrival of contrast can be seen, of course,

in the central venous line

and in the cardiac shunting left to right.

Example: Late Arrival in Liver

Now, this is an example of a late arrival

of the contrast agent in the liver.

You see that in this case,

you will see the first bubbles appearing in the arterial

tree of the liver.

After 20 seconds about,

now you can see the very first bubbles.

Normally you have eight to 12 seconds

that the contrast is arriving in the hepatic arteries.

And a time beyond 15 seconds is always suspicious for

a cardiopulmonary disease.

And of course, later,

after one minute, you can still see

the flow characteristic

and that the backward flow,

the reflux into the liver is

or can be seen very well.

This is the same patient.

And you can perform also doppler studies in the

contrast mode of the liver veins

and the portal vein, as you can see it here.

And you can see a hepato

ugal flow in the portal vein.

Troubleshooting: No Enhancement and Placement Issues

Other reasons why you cannot expect when you don't see any enhancement of the liver is,

of course, when so you bubbles

are going into the extra vasal space.

So that was a wrong needle placement.

And if you then look at the site

where the needle placement was taken, then you can see

that all the bubbles are in the top soft tissue.

And in contrast to levu, that was the first agent

that was on the market in Europe.

Levu was really hurting when it was

not placed, when the needle was not placed correctly.

But solar view is not hurting. Okay?

Bubbles under pressure, just like you see it here.

It's a milky agent,

but when it comes to high pressure,

then all the bubbles are being destroyed

and it becomes crystal clear.

The solution, if a patient is lying on the left

or right side or on that side, whether a needle was placed,

then the external pressure on the

on the veins on the major veins may be so high that

it influences the arrival time machine setting,

optimize the gain just below the noise level.

And the MI depends of course, on the ultrasound device.

In most cases, we have numbers between 0.07

and 0 point 12,

bit high in difficult scanning conditions.

So that is can be chosen

especially when you have not a very good

enhancement in the far field.

A focus position it is in with most machines

the focus zone is automatically placed in the far field,

start the clock when the contrast agent is injected

and look for bubble destruction,

especially in the near field.

So when you move slightly the transducer

and the image gets a bit darker

or the enhancement is then getting quickly less,

then this is a sign in the indirect sign

of a bubble destruction in the near field.

Contrast agent concentration is too high,

so then the enhancement is too bright

and that causes attenuation in the far field

volume storage of the question.

Organ indifference can planes.

That is important because we would like to document our examination in different scan planes,

and we'll try to store

c loops of the whole organ.

And of course, we have to check if the machine has

enough storage capacity, examination techniques

and contrast doses.

Examination Techniques and Contrast Doses

The worst the B mode image quality,

the less likely is a sufficient serious examination,

especially in the far field.

Number two, aim at the best B mode image quality

for a good serious examination.

And very often we turn the patient

around in the left decubitus position in order

to bring the region of interest closer to the transducer

and to have really the best image quality

and that will guarantee a good serious examination.

Lower the contrast dose of superficial lesions

and in lesions that already show a high vascularization

during when using color flow imaging.

Or when you look at the gray scale image,

if you see a posterior enhancement in the B mode,

then this indicates also that this lesion

might highly be vascularized.

So we then choose a lower dose of contrast agent in order

to avoid over saturation, increase the dose, then viability

of tissue is questioned as long

as no hyper vascularized tissue has to be passed

to reach the ROI

and higher doses are needed in high frequency probes

mostly doubled.

So if we use a seven

or nine megahertz probe, we double the dose compared to the

abdominal probe

and how much bubbles are trapped in the proximal tissue, like

in the spleen

or in the liver when we examine a an organ that is

behind these organs.

External Transducer Pressure

Okay, external transfuser pressure, as you can see it here,

this was a subcostal image of the right liver lobe.

And I was pressing very hard on the liver.

And you can see the effect that the near field

is not enhanced enough

because due to the pressure, you don't have

enough bubbles entering the

peripheral zone in this case.

And you can look at the sound shape when

you destroy the bubbles.

When you shortly have a high mi then you destroy the bubbles.

And when you turn around the transducer 90 degree,

then you can see the shape of your sound waves.

Bubble Size and Visualization Techniques

What is the real size of bubbles?

Of course, we know that bubbles are so tiny

that we cannot really image the

true size of a bubble.

It is just one third of a red blood cell.

But on the left image, you can see with an high eye

in B mode, the tiny bubbles

in the aorta and in the right renal artery.

And if you change to the contrast mode, low mi mode,

then you can see that the bubbles appear

to be a little bit bigger than in the

conventional B mode.

And of course, air bubbles are much bigger than the contrast

bubbles, as you can see it here,

here you see the air bubbles in the biliary tree

after papilla to,

and we have a technique that is named replenishment.

We destroy all the bubbles within high mi burst,

and then we switch again to a low mode image.

And then we see the reentering

of the bubbles in a lesion.

This here is a FNH, and you can see the central scar.

You can see quite nicely the

architecture of the vessels.

Accumulation Mode

The daylight pattern, Accumulation mode is also helping,

this is a metastasis

of a malignant melanoma in the neck.

And you can see here in the late phase

that only a few bubbles are entering this lymph node.

But if you accumulate over more than 10 seconds,

then you have an idea about the vasculature

of this lymph node.

And the next image shows you a second injection

of the contrast agent.

And of course,

this shows you much better the

vascularization of the lymph node.

And you can see also that there are areas

with the lower vessel densities in areas

with a higher vessel density, what is quite typical

for malignant lymph nodes

or malignant tissue definition of

liver contrast phases.

Liver Contrast Phases

And you can read that in the European guidelines

and also in the guidelines that will come up in

August this time.

The from the guidelines on the liver diseases

and the use of contrast, the arterial phase starts

10 to 20 seconds after IV injection.

We think with our experience eight

to 12 seconds would be more correct than the 20 seconds.

It ends after round about 30 seconds.

And then the portal venous phase is starting

and last until two minutes.

And beyond the two minutes, we talk about the late phase.

Liver Examination Technique

This is the examination technique that we have.

We look first during the arterial phase.

We perform a sweep

and look for hyper vascularized lesions

during the arterial phase.

And afterwards, we look for the right

and left liver lobe in the early

and late portal, venous face, subcostal,

cross-section and longitudinal scan plane.

And here's the late phase.

You can see that the liver is enhanced homogeneously from

the top to the bottom.

And of course, it is very important to look

for the arterial phase

because in the arterial phase,

we can best characterize the vasculature of lesions.

So like here you can see an FNH, you can see

during the arterial face already the central scar.

You can see the single vessels,

and you can see the venous drainage on the right image quite

nicely, drainage of the FNH.

Examples: Liver Lesions

And on the next image, you can see a patient

with a colon cancer and multiple metastasis in the right

liver lobe and giving contrast.

You see that only for a couple of seconds.

These lesions are hyper vascularized

and then are quickly being washed out.

Now you can see 1, 2, 3, 4 lesions.

Here are the lesions.

And when you watch it over time,

now they're starting to wash out.

So this is due to the high temporal resolution,

we can see quite nicely they're hyper vascularized the

status of these metastasis that is often being missed on ct.

Another example of a liver metastasis from ovarian cancer.

You can see the wash in of the contrast on the left image,

you can see quite nicely the very bright arteries.

Now the portal veins are filling

and you can see the network of tumor vessels in the metastasis

and being washed out very quickly.

And this is during the late phase.

After more than two minutes, you can see

that the tumor is nearly completely washed out.

Also, males have fages.

This is a 3-year-old male,

and we have examined this lesion

with a nine megahertz probe and injected two mls.

The other examples were performed with one

to 1.2 mls of so view.

And you can see quite nicely the

architecture of the vessels.

Again, this is the importance of the arterial face.

You can see it is now filling, it is growing.

So you have a century peel filling of the FNH.

Contrast Circulation and Transit Times

You should know the contrast circulation.

When you inject the contrast agent,

it first appears in the right heart,

then passes the first capillary bed that is the lung,

and then enters the left heart

and enhances the arter and its branches.

So the liver is first enhanced by the hepatic arteries

and then followed by the portal vein.

And the contrast filled blood in the portal vein has

first to pass the second capillary band

that is the intestine.

And also the spleen.

The arrival time in the hepatic artery is round about

nine seconds, three seconds later,

the portal vein is being enhanced, and

after 21 seconds, the hepatic veins are being enhanced.

And by that you can calculate the so-called transit times,

the transit time between the hepatic artery

and the hepatic vein is round about 12 seconds.

And the time between hepatic

or portal vein enhancement

and hepatic vein enhancement is roundabout nine seconds.

And this is an example.

This is a patient where we give the contrast agent.

You can see now the filling of the hepatic artery.

Now the portal vein is being filled.

And after couple of seconds, now you can see

that the liver veins also enhance.

And by that you can calculate the arrival times

and from the arrival times the transit times.

In contrast, you can see a patient here with multiple liver metastasis.

You can see that the arteries are filling,

but the portal veins fill up very late

and nearly simultaneously with the contrast filling

of the hepatic veins.

So if we look, we did a study here,

and you can see the transit times between a group

of control healthy patients compared to those

with an FNH, liver cirrhosis, liver metastasis.

And you can see that the time difference between enhancement

and the hepatic vein and hepatic artery is

12 seconds in the control group.

Nine seconds in the FNH,

this is a much younger population also.

Liver cirrhosis, 6.8 meta testis 8.8 seconds.

And if we look for the transit time between the HEPA vein

and the portal vein, then the control group

we measure the time of nine seconds.

The FNH is 5.5, liver cirrhosis, 1.5,

and liver metastasis 4.4 seconds.

Tools and Criteria for Characterizing Focal Liver Lesions

We have different tools to look for the liver,

for example, we have B mode image.

We have color doppler, we have pulse,

wave, doppler and Sears.

And we have criteria

with which we can characterize focal liver lesions.

First of all, we have to look for the liver itself.

Are there any, is there any background pathology in the

liver, like a cirrhosis?

Are the lesions predominantly EPO or eridge?

Do we see a halo?

Do we see a typical architecture like a staite pattern?

In FNH, do we see a lesion

that is homogeneously

or in homogeneously from its gray scale appearance?

Do we see calcification cystic areas?

Does the tumor invade neighboring structures?

Do we see secondary tumor effects, like

enhancement or shadowing?

And that gives us a diagnosis.

And then we should check how confident are we

with this diagnosis?

And can color doppler maybe increase the level

of confidence or see us?

And seal is definitely the technique

with which we can characterize lesions best.

Enhancement in Other Organs: Spleen and Kidney

With ultrasound, the spleen enhances in a different way.

We know that the spleen has an open and closed circulation.

And due to this fact, the spleen is during the washout,

wash in time not homogeneously enhanced.

You can see that there are some bands

with less enhancement in the spleen,

but if you wait, just like in ct,

after one minute, you have a complete homogeneous

enhancement of the spleen.

Now looking for the kidney, you can see now the contrast is

arriving and you can see a nice enhancement

and homogeneous enhancement of the renal cortex.

So we have first a cortical enhancement followed

by a medula enhancement,

and the medula enhancement progresses from the peripheral

zone to the lyase.

Then we have a parenchymal phase with an iso enhancement

and a washout phase that starts

with a medulla being washed out,

and then the cortical washout.

And here you can see the placement

of ROIs in different positions,

the yellow one in the cortex.

Then the next is placed in the outer area

of the medulla and the red in the more central part.

Artifacts in Contrast Imaging

Artifacts, of course, we try to avoid artifacts,

but they are there.

And there are some classical ones,

like you can see it here.

This is a patient with a fatty disease of the liver.

You can see a cyst

and the cyst is attenuating not attenuating the

sound waves.

So you can see much better posterior to the assist,

the enhancement of the liver parenchyma.

And here you have an insufficient enhancement in the far

field with a high frequency that is being used in this

contrast setting.

But we can also change the transmit frequency in contrast, so then we can

image the far field much better.

And this has of course, a very practical aspect.

As you can see here, we see multiple

metastasis in the liver.

And when we go down with the transmit frequency,

then we can also image the metastasis.

In the far field mirror artifact, of course,

mirror artifacts appear in contrast,

just like in gray scale image

attenuation is an important issue when we

look at the contrast studies of the liver and other organs.

Phantom Study on Attenuation

So what we did was we were looking at a,

and we were building up a phantom,

and we tried to figure out what is the effect

of attenuation to tissue.

You can see there are two phantoms

and pump were pumping blood

through a tube that is passing the two separated phantoms.

And with machine number one, we produce a high mi

and destruction of the bubbles.

And machine two is continuously scanning at a low mi.

Okay, now this is the phantom.

You can see the tube being filled with contrast.

And now the first machine completely destroyed the bubbles.

And now the bubbles come back in the tube

and did, what did you see else?

So when we position our ROIs within the tube

and behind the tube, then you can see the

destruction of the bubbles.

And you can also see that the tissue behind the

tube is less attenuated when you have to destroyed the bubbles.

So this is an important finding,

and you can see that also when you look at vessels

with a high contrast dose, like here,

this is a common carotid artery and a soft plaque.

And you can see during the wash in phase that the very high

dose of the contrast does not allow the visualization

of the distal part of the vessels.

So this is due to attenuation to a very high

bubble concentration in the near field.

And when you look at the time intensity curve

and you position with a very small

ROIs in the near field, the midfield

and the far field in the vessel, then you can see

that influences really the time to peak numbers.

Recommendations for Vessel Imaging

So that also means that when you look at vessels

you have to look for a maybe different

examination strategy.

So we would recommend to use one

or multiples small contrast agent doses.

So the intraluminal enhancement time will then be a bit

shorter than what you do or inject higher doses.

But the advantage is that you have no,

or only little intraluminal attenuation

and less attenuation caused by solid organs.

Like the liver, the spleen,

or the kidney that are positioned proximal

to the vessels are also of advantage for the vessel imaging.

This is an example. So you can see the spleen

and the left kidney.

And due to the attenuation

of the contrast filled spleen, the enhancement of the kidney

behind the spleen is much less than the part

of the kidney that is on the lower pole,

and it's not being covered by the spleen.

Examples of Specific Artifacts

Another example, this is a lymph node

metastasis from a melanoma.

You can see the color doppler examination of the right.

And if we now inject the contrast, then it looks like

as if the near field is not enhancing And

that there is maybe a necrosis in the near

field of this lymph node

Because We do not see any bubbles in the near field.

Is that correct? When we perform a sweep over

the lymph node in the late phase,

then we see, or after one minute, then we see

that the lymph node is nearly homogeneously being enhanced also in the near field.

So the answer to the question did we have a,

or do we have a necrosis in the near field, we can say,

no, of course not.

But due to the continuous scanning in one scan playing cause a

destruction of the bubbles in the near field,

and that gives the false impression

of a necrosis in the near field.

So this is clearly an artifact,

This is another artifact, very important one.

It's the glare artifact.

You see a hemorrhage cyst of the left kidney,

and when the spleen is being filled up with contrast,

then this glare artifacts produces

stationary echoes within the cyst.

That may give the impression that there is

some viable tissue in the cyst.

And that is definitely not the case. This is an artifact.

Advanced Techniques: Lesion Vasculature and 3D Imaging

And last not least, we were looking for lesions

and trying to figure out what is the

vasculature within the,

or the architecture of the vessels in the lesion.

And we can also apply a 3D technique in contrast.

So this is the scan plane that we were using

for the image that you can show that you can see here,

you see here 3D imaging of an FNH in two scan planes.

And you can see that

not only one vessel is supplying the FNH, but two.

Okay. And this may be of an advantage in future,

especially when calculating the blood volume within tumors.

Conclusion

Thank you very much for your attention.