Scrotal Sonography: Tips and Tricks of the Trade - HD

Introduction and Educational Objectives

I have no financial disclosures.

My educational objectives are basically my outline.

First thing I'd like to review is to review the vascular anatomy of the testis, and talk about how it helps in performing and in interpreting Doppler exams.

I'd like to address the vas deference and hopefully you'll be able to recognize the normal and abnormal vas deferens.

I'd like you to be able to understand the appearance and the importance of gray scale findings in the evaluation of testicular torsion.

And finally, I'd like you to know the differential diagnosis for incidental non palpable intra testicular masses and for solid extra testicular masses.

Vascular Anatomy of the Testis

Let's go over the vascular anatomy first.

This is a diagram that comes from the second edition of the ultrasound requisites, and it shows the testicular artery coming down from the spermatic cord coming along the posterior aspect of the testis and then ramifying into centripetal or into capsular arteries.

There's usually several capsular arteries.

One is shown here.

You can see that the capsular arteries provide branches called centripetal arteries that head into the testicular parenchyma towards the mediastinum, and then ramify in the opposite direction and vessels that are called recurrent rami.

But if you look in this region where the mediastinum is, there's very little arterial vascularity, just small vessels there.

Now, if you look on doppler and you rotate it into the normal orientation, you can see these centripetal arteries in the recurrent rami quite well.

Mediastinum is down here.

And here is this relatively hypovascular zone near the mediastinum.

And notice there is one little vessel here that we'll talk about later.

Anatomists never really realized that there were a lot of testes that had something called a trans mediastinal vessel running through them.

The anatomists thought that this was either didn't occur or that it occurred very rarely, but in fact it's almost a normal variant bordering on normal.

It occurs in 52% of testes.

It's present unilaterally in 50% bilaterally.

In 25% it's absent and only 25%, and in 8% it's multiple.

So if you look at this transverse view, you can see the centripetal artery here, recurrent ramus.

Here's a capsular artery, but there's also a big prominent artery that runs through the mediastinum to the opposite side of the testis with blood flow headed towards the opposite side of the testis.

And these trans mediastinal arteries then supply capsular arteries with ultimately supply the centripetal arteries.

Now for all of you that do dopplers and bill for doppler exams of the testes, you realize that you have to make a comment in your report about the presence or absence and quality of arterial inflow in venous outflow.

So you and your sonographers need to know where to find the venous outflow.

And when there's a trans mediastinal artery like this, there is often a visible vein running parallel to it.

You can see that on color doppler, not always, but in some situations.

And if you do doppler analysis and open up your sample volume, you'll be able to see the arterial flow in one side of the baseline and the venous flow on the other side of the baseline.

And many times when you have these trans mediastinal vessels, you can see them on gray scale.

What if you don't have a trans mediastinal vessel?

Then where do you look for the veins?

Well, you can see the veins really well.

They show up much more prominently in cases where there's hyperemia.

So this is a nice example where we've got a normal right testis and a hyperemic left testis in a patient with oris, not much blood flow in this region on the right, but a lot of flow here on the left, and it's all heading towards the mediastinum.

If you do doppler analysis of these vessels, you'll get an arterial waveform.

These are the recurrent rami that are heading away from the mediastinum.

But if you do doppler analysis of these vessels, these are veins that are heading through and to and through the mediastinum and they have a venous waveform.

When there's hyperemia like this, the waveform often is slightly pulsatile, but that should not be confused with arterial flow.

Here's another patient with oris.

And you can see this intense hyperemia with readily detectable venous flow down here near the mediastinum.

And a lot of flow in the recurrent rami here, which are usually relatively unimpressive.

And what about normal testes?

This is a normal testes.

And you see there's not much blood flow down here, but there is one little vessel that's one of the normal testicular veins.

You'll see them occasionally on color doppler and be able to get waveform from them.

You can see here when we take the waveform, it's a very low velocity venous signal less than two centimeters per second.

Now it's completely normal to be able to see no venous flow in the testis at all.

And when you see that you just report in your report that venous flow is not detected, this is a normal finding.

Another important thing in doing doppler exams is comparing the two testes to see if one is hyperemic or under perfused in the transverse view, it's easy to see that the vessels run in vascular planes, in this case from upper right to lower left.

In a longitudinal plane, it's harder to tell that.

So if you were to scan this testes in a longitudinal plane like this, you would see the vessels elongated, they'd be very prominent.

It would look like there's a lot of flow in that vessel.

But if you look in this plane, you're gonna be viewing those vessels in cross-section and it will look like it's less vascular.

This is the same testes, it's just that you're looking at it in two different planes.

You have to keep that in mind when you're interpreting comparison views of the right and the left testes in longitudinal planes, you also have to pay attention to that in the transverse plane.

So this is the same as dual image images.

And you see the mediastinum here, very little detectable blood flow.

And that's because the vessels are oriented at a Doppler angle of about 90 degrees, and it's just very hard to detect blood flow at that angle.

Here on the right, the testis has rotated a little bit, the mediastinum down here, and this is the orientation of those vessels, a much better doppler angle and they're much easier to detect.

It's the same testes, but it's just flow that's readily detectable in one orientation and not as detectable in the other.

This is a patient that presented with a left scrotal pain.

You get your comparison views of the right and the left side.

The vascularity perhaps is a little greater on the left than it is on the right, but it's a pretty subtle difference.

Notice in this case, the mediastinum is down here.

In this case, the mediastinum is a little bit more laterally oriented when you readjust the direction of the probe so that the mediastinum is oriented in the same location on both, you get similar sensitivity bilaterally.

And it's clear that this is a hyperemic testis.

So when you're doing Doppler exams, you want that mediastinum to be posterior as much as possible.

And this is just one little tip that I'll give you.

The sonographers often like to get this view where they show both testicles on the same image trapezoidal formats.

So as you compare the appearance and the vascularity of both of the testes, and I think this view is absolutely terrible for doing both of those things.

The testes are very accommodating organs, but they rarely sit symmetrically like this in the scrotum.

It's usually like that, or it's like this or one's way up here and one's way down there.

It's very difficult to get symmetric views on the same image.

So instead, you should go to a dual screen format, optimize your visualization of one testes, and then optimize your visualization of the other testes, orient them symmetrically, and that way you can get a fair comparison of the vascularity.

So this view is really only good for showing that you absolutely have two testes.

It's not good for comparing the two.

Evaluating the Epididymis for Vascular Assessment

And there are some lessons to learn from evaluating the EPIs that can help with vascular evaluation.

So the in the normal anatomic position, the epididymus is posterior to the testis.

And when it's posterior, it's often not that easy to find sonographers struggle with that.

Sometimes when you happen to be lucky in the test or the epididymus is located lateral to the testis like this, it usually is much easier to see.

So many people have developed skills at kind of moving that testis around, moving the EPIs around so that it is easier to see.

So here's a an example.

Epi demus is posterior to the testis.

In this case, it's pretty easy to see, but many times it's not.

But it's always easier to see when it's rotated up into the anterior aspect of the image.

Well, how do you accomplish that?

If you look at this image, here's the epi demus posteriorly.

If you take the transducer and you push and rotate the probe out laterally, then that tends to rotate the testis so that the epidermis rotates anteriorly.

So pay attention to this.

This is the epidermis and as we move the transducer laterally and then push the testis rotates and notice that's the mediastinum that is also rotating with the epidermis.

The two are very close together and they rotate with each other.

So to get the epidermis and the mediastinum posterior, which is where you want it to evaluate the vascularity, you do just the opposite.

You rotate your probe medially and you release a little bit of pressure.

I don't know how many of you have been extremely frustrated by the cremasteric muscle.

But it can really be a tremendous pitfall when you're trying to evaluate scrotal vascularity.

It results in skin thickening, corrugation of the surface of the skin, a lot of sound attenuation and refractive shadows.

It can just completely wipe out the detectable vascularity in the testes.

In addition to decreasing the echogenicity of the testis can make it very difficult to evaluate.

This is just a case where we see tremendous refractive shadowing from this sort of corrugated cremated scrotal wall.

So how do you avoid that?

Well, keep the room warm and use warm gel.

How do you overcome it?

Reduce your transmitted frequency just so that you can kind of blast through the scrotal skin.

And then sometimes you just have to wait it out and hope that it will relax.

So here's an example where we can see the scrotal skin is 7.4 millimeters in thickness and there's very little detectable blood flow in this testes and it looks very dark because of the sound attenuation later ons, scrotal skin's starting to relax a little bit.

We're beginning to be able to detect some blood flow in that testis and it's starting to regain some of its echogenicity and later on, yet it's even thinner.

And now we're starting to see more readily detectable blood flow.

The Vas Deferens

Next I want to move on to talk about the VA deference.

I don't know how many of you make that a part of your scrotal examinations.

Probably not many, but you should at least be able to recognize the VA deference.

So the anatomy is shown here in this diagram.

There are multiple tubules in the epididymus that converge into a single sort of convoluted tubule that becomes the vast deference in the inferior aspect of the scrotum.

This epi or this vast deference is very convoluted, but as you get up higher in the scrotum and into this spermatic cord, it straightens out.

This is the area that I want to kind of focus on.

Now, the histology of the VA deens is kind of interesting.

It has an inner and an outer muscular layer and a inner middle circular layer that are very thick, especially thick compared to the lumen of the epidermis.

And that's well shown here on this histologic cross-section.

And you can actually see it well on sonography.

This is a resected VA specimen from a vasectomy and of a water bath.

And you can see how well this reproduces the histology of the vast deens.

And you can measure the thickness of the vast deferens and measure the luminal diameter.

In this study, the thickness range from 1.5 to 2.7 millimeters and the lumen range from 0.2 to 0.7 millimeters.

So we're really talking about highly high resolution to resolve this.

When you look at this matic cord, you see a lot of structures.

Most of these are vessels, but you can see the anatomy of the VAs deens here.

When you compress the cord, the vessels, the veins at least will compress and all you'll be left with is the VAs deference and one or two arteries.

So this is the VAs that's the spermatic artery there.

So how do you tell the difference between the deference and the artery?

Well, you just do doppler.

So you start like this with the baseline where you see all these structures in the spermatic cord, you compress them, then you turn on doppler.

Anything that's left is gonna be either a vessel where you'll see the doppler signal or it'll be the VAs deference.

And here you see the vast deference with the little luminal reflections.

Now, the vaso epidermal loop that I showed you in that diagram is really hard to see sono graphically.

It's unusual to be able to find the two in the same plane so that you see the epidermal tail and the vast deference.

Usually you'll see the epi epidermal tail, and then you move the transducer laterally or medial, and you'll see the origin of the vast deference.

In this case, you can see them on the same image.

And here's a case where you can see the two in this nic clip.

So this structure that is oriented parallel to the epidermal tail immediately adjacent to the epidermal tail is the origin of the vast deference.

So what does it look like when it's abnormal, when it's obstructed?

This is a 35-year-old man that presented with a right scrotal mass.

On the left side you can see the normal epidermis.

Up here on the right you see this enlarged congested appearing epidermis and this unusual kind of multi cystic looking lesion inferior to the epidermis.

Well, that actually turns out to be the vast deference, which you can see running parallel to the epididymus here.

And you can see on the nic loop that this structure communicates with the vast deference.

So don't scratch your head when you see the vast deference or when you see a dilated vast deference.

It's something that you should come to recognize.

Testicular Torsion: Gray Scale Findings

And I wanna move on to testicular torsion and really focus on the grayscale findings.

I think everybody is pretty familiar with the Doppler findings, but the grayscale findings are important as well for a number of reasons.

They can provide information about the viability of the testis.

They can provide diagnostic information both by making an alternative diagnosis and also in assisting to make the actual diagnosis of torsion.

Just as we heard earlier how it can help in diagnosing ovarian torsion.

It also is very useful in diagnosing testicular torsion.

And then it can also help in guiding management.

'cause when you look at the torso spermatic cord, you can see the direction of the twist.

And if you want to detours that testes, then that's important information to have.

And then the information about viability can also provide information about urgency of the surgery.

Prognostic Information from Gray Scale Findings

So what about prognostic information?

Well, this is a study that looked at a variety of gray scale findings.

And it found in a series of patients where there were seven non-viable testes and nine viable testes, that a hundred percent of the non-viable testes had an abnormal echogenicity and none of the viable testes did.

There were other differences, none that were quite as stark as that.

I mean, for instance, detectable flow was only seen in a few of the viable testes never seen in a non-viable testes.

Increased wall thickness was only seen in the non-viable testes and not in the viable testes.

But this abnormality in echogenicity was the main differential.

And here you can see one of these testes is torsed.

I can't remember which one it was, but it was viable.

And then here, this testes that's enlarged and hypo coic was non-viable.

This was a study that we did, sort of preliminary study and it's been pretty much corroborated in subsequent studies where they looked at the salvage rate with respect to the gray scale findings.

In this particular study, 64% of the testes that were normal were salvageable.

50% that were either hyper coic or hypo coic diffusely were salvageable, but none of the testes that were heterogeneous were salvageable.

And in this larger study, 89% of the normal testes were salvageable and none of the testes that were heterogeneous were salvageable.

And interestingly, in this study, when you look at the duration of pain, which is also supposed to be a predictor of salvageability, it was very similar in those two categories.

So the gray scale findings were more reliable than the clinical findings.

Diagnosing Testicular Torsion with Gray Scale Findings

So what about diagnosing testicular torsion with gray scale findings?

Well, it is helpful.

You can see the twisted cord.

This was originally described in pediatric radiology in the late 1990s in a series where all 23 of the cases of torsions had some clue about a twist in the cord on them.

And in nine of the 23, it was the only finding it was better than colored doppler, which I think is unusual.

But that was the case in this study.

I'm gonna just skip to this study because it's got a larger number of cases.

This is the study that sort of popularized looking at the cord.

In cases of suspected torsion, there were 64 cases of torsion and they saw some clue that the cord was twisted in all of them.

And in four of the cases where the torsion was incomplete, it was a more reliable sign than color doppler.

So let's look at that a little bit.

To find a twisted cord, you start in the transverse plane, little bit above the level of the testis, four to five centimeters above the testis, and then you just bring your probe inferiorly and you look for a twist in the cord.

So this is looking at the cord as we come down.

You can see the twist very similar to what Lori showed you in the ovaries, although I think it's easier to see in the scrotum.

So this was the baseline scan.

This patient was manually detoured.

And when you look at the cord after detour, you can see that that twist has disappeared.

Now, another clue that you've got a twisted cord is an abrupt transition between a normal cord above and all of a sudden a congested thickened en large cord down below.

So in this transverse view, as we start up higher, you can see the normal cord and then you sort of lose the cord and you see this enlarged sort of in homogeneous non-specific mass.

And that's part of the inferior aspect of the cord that's congested.

Another clue is the tip of the iceberg sign, and that's where you get a twist in the cord, a very tight twist and a lot of refractive shadowing off of that twisted cord.

It looks like a little pearl with a shadow.

And here you can see it on the cine clip.

So be aware of that 'cause that sometimes won't look like an actual twist.

You'll just see that little area of tip of the iceberg.

And then the final is the whirlpool sign.

Again, just exactly like we saw earlier with ovarian torsion.

And it looks very similar.

Some people call it the hurricane sign.

And I, you can see that this is a picture of hurricane Florence and the similarity here is pretty striking.

And here you can see on the cine clip, as you sweep down, you just briefly see that little whirlpool sign as you go through the cord.

And then the torsion knot.

So this is something I was not aware of until Tom Stavros told me about it.

This was years ago he said.

So that's what I've been seeing all these years in these patients that have a tors essis, and it's called a torsion knot, but it really doesn't look like a knot.

It looks just like a heterogeneous sort of solid per testicular lesion.

And, if you don't know what to expect, you really won't be have a clue what this is.

And in fact, many times sonographers confuse it with an enlarged epidemo.

As you can see here, this was labeled left epididymus, but this is actually part of the torsion knot.

And then finally, the underlying abnormality that causes torsion is bell clapper deformity.

And you can see the bell clapper deformity on gray scale if there's enough fluid.

So here you can see the testis fluid surrounding it on all sides.

Same thing here.

Now the testis does make contact with the wall of the scrotum here, but the angles are acute in a normal scrotum.

If there's a hydro seal around it, the angles will be obtuse.

And it's clear that this testes is attached to the wall of the scrotum.

This testes is not.

So here's a cine clip where you can see that the inferior aspect of the cord and the testis are surrounded by fluid.

So this is a bell clapper deformity.

And the reason these things are important is because there are cases where the blood flow to the testis is relatively well maintained despite the fact that it's tors.

And here's an example where we see the right testis, readily detectable flow, left testis readily detectable flow.

But this patient had pain on the right and clearly he has a bell clapper deformity here.

And in addition, he has a cord that abruptly terminates here.

And you have this big swollen aspect.

So this was a patient with torsion where the gray scale findings were the clue to make the diagnosis.

Guiding Management with Gray Scale Findings

And then management, you can also guide management by looking at the gray scale findings.

Here's a patient that clearly has torsion of the left testis, normal right testis.

When you look at the direction of the twist in the left side, you can see as you come down that's rotating in a clockwise position.

That means that that testis has torsed in a lateral direction.

Normally we think that the testes torse in a medial direction, and to detours them, you have to open the book, twist them in a lateral direction.

But actually lateral torsion is not all that uncommon.

This is the most recent study that I could find, and it was almost half of the testes.

The torsed actually torsed in the unexpected direction.

So you need to know that before you detours them.

And here again is a case that was detours and you can see following the detour and the twist disappears and you see the hyperemia in the post ischemic testis.

Incidental Non-Palpable Intra-Testicular Masses

Now I wanna finish up a little bit with talking about masses, not your run of the mill masses, but specifically talk about non palpable intra testicular masses.

And how do you deal with those?

There's a nice paper that came out recently from the European society of Euro Radiology that looked at this specifically.

And the bottom line was that many of these non palpable incidental masses are benign.

Many of them are light cell tumors.

So when you report on these patients, you shouldn't give the clinician the impression that this is very likely to be malignant.

We're all taught that intra testicular masses are malignant, and that is true, but when you're detected incidentally and they're non palpable, a sizable percentage of them are not malignant.

So don't lead the surgeon to necessarily do a complete orca orchiectomy in these patients.

And in fact, when the lesion is small, less than five millimeters, and the tumor markers are negative, it's a reasonable approach to follow them.

Here's an example.

This is a patient that presented with a sperm seal on the left, but had this incidental lesion on the right that clearly looks like a neoplasm solid vascularized.

We suspected that this could have been benign, but couldn't rule out malignancy either surgeon decided to resect it and it did in fact turn out to be a light cell tumor.

Now contrast that with this lesion, even though there's no detectable vascularity here, there is micro theis, which raises a big red flag, and there's a second little lesion here as well.

So to make yourself a little bit more confident, do what you tell your residents to do.

And that's look up in the retroperitoneum.

And in this case, when we looked at the retroperitoneum, there clearly is adenopathy.

So that kind of seals the deal here.

Biopsy is also something that we don't consider often in the United States, but it is a viable possibility.

A nice paper that Vikram dra and one of his colleagues from India wrote that I would refer you to.

And they made a couple of relevant points.

First, that biopsies, needle biopsies are well-established in patients with infertility.

They're not widely used for focal lesion based on the assumption that the risk of malignancies high enough that those testes have gotta come out anyway.

So why biopsy?

And also the fear of seeding the biopsy tracked and altering the lymphatic drainage.

This fear is probably not warranted even though it is slightly increased, it's not statistically significantly increased.

And it's based on studies that talk about scrotal violation.

And most of those studies, the violation of the scrotum that occurred was surgery.

You know, they went in, they went through the wall of the scrotum to either biopsy or resect the testis.

And that's much more invasive than doing a needle biopsy.

But you don't need to do it very often.

Here's a patient with CNS lymphoma on PET scan, had a solitary lesion in the testes, no disease, any place else in the body.

And they were, and you could see that there clearly was a focal abnormality on ultrasound.

And they did want to get a diagnosis before they treated the patient.

So we agreed to do a biopsy and you basically do it just like you do any other biopsy.

The trick is you have to immobilize the testis.

So in this case, we put a tourniquet around the testis to keep it immobile.

Had one person holding the test, that's the other person dealing with the needle and the transducer.

And this was confirmed to be lymphoma.

Solid Extra-Testicular Masses

Finally, extra testicular masses.

We think of extra testicular masses as being benign, and that's true.

But the reason that they're benign is the majority of them are these four lesions, sperm seals, cysts, varicose seals and hydro seals.

That is an easy diagnosis to make on ultrasound.

The ones that you have trouble with are the minority that are solid.

So what do you do with a solid extra testicular masses?

Well, here's an example.

Here's a testis, a super testicular mass.

You can see that it's right next to the epidermis, but it's not arising from the epididymus.

It's separate from the epidermis.

And those of you that are probably sharp recognize that it's iso coic and looks just like the testis.

And this is actually a case of poly anorism.

Localizing ex testicular masses is important.

There's a variety of techniques that you can use.

One is transducer pressure.

We use that every place else in the body and you can use it in the scrotum as well.

Here.

This lesion that we thought might be arising from the head of the epididymus is probably too mobile to be arising from the head of the epidermis.

We weren't smart enough to figure that out and we couldn't separate it from the EPIs, but in fact, this turned out to be a cystadenoma of the appendix of the epidermis.

Another technique is transducer retraction.

So what do I mean by that?

When you have lesions that are on the surface of the testis, it's sometimes very hard to tell if they're testicular or if they're in the scrotal wall.

If you apply a lot of gel to the transducer kind of acts as an adhesive, and then you pull the transducer away from the testis, it will pull the wall of the scrotum away from the testis.

And a little bit of fluid will flow in between the testis and the wall.

And as in this case, you can see that this is clearly part of the testis.

And this is a plaque of the tunica albu genia that's contrasted to a case like this where the plaque is arising from the tunica vais and not from the surface of the testis.

You can also use real-time palpation to help you figure out if the lesion you're seeing is palpable.

And if the thing that you're palpating is actually the visualized structure on sonography.

So here's a patient that had a little extra testicular lesion.

We weren't sure if this was what the guy was palpating and not, so he showed us, just put your finger underneath it, your probe on the opposite side and palpate it.

And you can see as your finger moves here, it's right next to this little lesion.

So the list of things that can cause extra testicular lesions is long.

The most common is the adenoid tumor, but there are a lot of other benign and malignant tumors that can be solid extra testicular lesions.

We're gonna start and just talk briefly about the adenoid tumor 'cause that's the most common.

It's benign.

It arises from the mesothelium of the tunic and vaginalis.

And because they're usually small and outside the testis, they usually don't get resected.

So there's not great sonographic literature on the appearance.

But what there is usually describes them as solid masses that are hypo to hyper coic and they arise from the epidermis or the tunica of the testis.

And here's an example of a little adenoid tumor that's hyper coic in the tail of the epidermis with some detectable blood flow.

This is a classic ad rheumatoid tumor here, tail of the epi demus with a mass arising from it.

But this tends to be uncommon in my experience.

Most of the time they tend to be plastered up against the testis and appear as little hyper coic lesions.

Or as they get bigger, they get a little more heterogeneous and hypoechoic as we see here.

But all of these are adenoid tumors.

This is a really nice study that Mary Frady and her colleagues at the Brigham did in the late nineties.

And they looked at all the per testicular lesions that were resected and evaluated histologically.

They had 19 cases, three of them were malignant.

Now extra testicular lesions aren't supposed to be malignant, but three of them are malignant in this case.

And they were all sarcomas.

The rest were benign and most of those were adenoid tumors.

And in their series there was no difference in the appearance, the size or the location of the lesions.

Now realize this is a very selected case.

So there's a selection bias here.

'cause these are just the patients that went to surgery and there were probably many that were small benign lesions that didn't go to surgery and didn't get entered in this study.

This case here is a leiomyoma.

On the other hand, this case is a MOC sarcoma.

It's bigger, it's a little more heterogeneous and has a lot of blood flow.

This is another MOC sarcoma.

And you can see it looks very lobulated.

This is a very angry looking lesion.

So just be aware that just because it's extra testicular, if it's solid and it's sizeable, then you do need to worry about malignancy and those should probably be resected.

Summary

So in summary, the take home points I'd like you to remember is that the vessels of the test is radiate toward the mediastinum.

And the orientation of the test is is important When you assess both arterial and venous flow, when you compare one testes to the other, cremasteric contractions are very detrimental, especially to doppler sensitivity.

And you have to know how to deal with that when you encounter it, the VAs deference is reliably visualized.

You should be able to recognize it when you see it.

Familiarity with the gray scale findings is important in the assessment of testicular torsion for multiple reasons that we all went over.

Small incidental, intra testicular masses are frequently benign and they don't need to be resected in all cases.

Ultrasound follow-up is a viable approach when they're small needle biopsy is also a viable approach that you won't need to use often, but you can use when needed.

And then finally, solid extra testicular masses should not necessarily be assumed to be benign, especially when they start to get large.

So thank you all very much for attention and again, thanks to the program committee for inviting me to.