Advanced Techniques in 3D Ultrasound : Fly Thru - SD

Introduction to Advanced Techniques in 3D Ultrasound Fly Through

It's been a delight to actually be one of the first folks in North America, probably to have had the ability to actually use the technology I'm going to be talking about tonight.

We've entitled this Advanced Techniques in 3D ultrasound fly through, and when you see these images, you'll understand why the folks at Toshiba came up with the idea of fly through.

It really does represent a completely unique method of processing ultrasound images and a unique way of looking at structures within the body.

As you can see in this image here, we have several images, which are the typical gray scale, multi-format, multiplanar imaging.

But of course what's unique is the image at the bottom of the screen, which is a fly through of the aorta.

This is something that we, I personally have had limited experience with.

I've been lucky enough to use the machine over the last several months before its actual introduction, but it certainly is a unique way of looking at the body, one that we've certainly not seen, at least in the ultrasound world before.

What is Fly Through Technology?

What is fly through technology?

As we said, it's a new perspective in 3D imaging for ultrasound and as opposed to the regular 3D or even so-called four D imaging that we do, we tend to look from the outside in.

And as you could see from that imaging, this is really the first time I think ultrasound has done a turnabout and is now looking from the inside out.

The term that the engineers have given this is perspective imaging because it gives you a different perspective of the way you're looking at various body cavities.

And it really is perspective imaging of an acquired four D ultrasound volume.

You're virtually, as you could see, traveling through a body cavity.

The images that you've just seen, and you will see for those of you who do CT or CT virtual colonoscopy, have a very similar feel to that.

And some of these you would actually probably be hard pressed to tell the difference in whether they were ultrasound or ct.

4D Versus Perspective Imaging

Four D versus prospective imaging.

Typical four D imaging really uses a parallel projection, and so one's viewpoint is essentially infinite, and therefore it's very difficult to get any sense of depth or really what's around you.

The fly-through technology uses what's known as perspective projection, where the image is really much more displayed exactly as what you would see is fewer doing an endoscopic procedure of any one of a number of body cavities.

Ways to View Fly Through Images

There are various ways that one can actually view these images.

The machine itself will actually navigate through structures for you, and the observer's eye, or really the machine or what we look at, moves according to the center line of the blood vessel.

And so in this particular case, you would see the surface around you and it would be displayed as such here.

But then the actual projection as you go through the vessel will travel directly through the center line of it, whether you're looking at a blood vessel, the gut, or any other fluid filled structure within the body.

And again, this is another example of allowing the machine to go into auto mode so that it essentially passes through the tubular structure.

You can see it branching here.

This particular case, it kind of decides for you which of the branches it's going to go into.

So this can actually be done automatically for you as you go through, in this particular case, the branches of the portal vein.

There is also the possibility of doing actual fly through navigation yourself, and it depends on what it is you're looking at and what it is you'd like to know.

In this particular case, what you can do here is to actually direct the arrow or the line of sight, the prospective line of sight, through the bowel in this particular case, but you will actually be able to direct it in this particular mode of navigation where you do the directional navigation.

If you are, for example, looking at a bifurcating vessel, you can actually choose which of the two vessels you'd like to go into and interrogate.

Likewise, if you are looking at a polyp, for example, in the endometrium, you can actually come around the back of it and see it from behind and get a different perspective.

So, the machine can do it for you or you can actually navigate yourself through some of the structures of the body.

Reconstruction Time and Advantages

The reconstruction time for this technology is quite rapid.

As I mentioned, we have automatic and manual visualization modes.

Obviously since we're dealing with ultrasound, you don't have the problem of ionizing radiation.

The volume itself is actually stored on the ultrasound unit, and it is viewed after the examination is complete.

And for that, that considers the fact that of course, you don't have to come in and interrupt the examination while the patient is being scanned.

It can be reviewed later on.

Overview Mode

There's also an interesting overview mode, which I'll show an example of in a moment, which we've actually found some beautiful images.

I'm not quite sure what to do with them, but they're really beautiful images and that's part of what will happen with this technology is at this point, it's a technology that we will be looking to try to figure out how it can help us in our practice.

But we do have an overview mode possibility where we've looked at fluid-filled bowel or pelvic structures, pelvic organs like the uterus or ovaries when they're surrounded by fluid.

It is kind of a unique way of looking at the bowel in this particular case in a patient with ascites.

And you can manipulate this, you can look at various parts.

As I said, it's kind of an offshoot of the actual way or the reason that the technology was done, but can give you some rather interesting images.

We've seen also, as I said, uterus, ovaries and the surface of them, probably the peritoneum as well is another area where you may be able to use this kind of overview mode.

How to Perform Fly Through Imaging

Basically. How do you do this?

It's very simple.

It is acquired just like you would acquire any other normal 3D data set.

On the machine, there's a button, you hit the fly through mode, you point the arrow in the direction you'd like it to go.

You hit start and off you go, you're flying through.

So it's a very simply performed procedure.

Takes a little bit of getting used to, if you're actually going to do the navigation mode yourself, that takes a little bit more learning curve.

At this point, as I said, a number of us including Dr. Fisher, who you'll see in a moment, have met in the past.

We've obviously worked with the Toshiba people and at this point we were trying to come up with some ideas at one of our previous meetings, where would be the places that this might actually enjoy potential clinical applications.

Potential Clinical Applications

Endometrium and Virtual Hysteroscopy

The first thing that came to mind was, of course, in the endometrium.

The endometrium itself, of course is a solid structure, but if it's distended with fluid, as would be the case with a sa saline hy sonogram, as you will see, you're actually able to obtain what is essentially virtual hysteroscopy.

Obviously this would be a new way of looking at polyps, mitus syn, and practically anything else that lives in the middle of the endometrial canal.

Breast Ducts

The technology is actually capable of seeing relatively small fluid-filled structures, and for example, I'll show some images of dilated ducts in the breast.

The idea with this would be, and some of this work has been done in Japan, looking for example, a patient suspected of having intraductal papillomas.

Vascular Imaging

Obviously, I suppose one of the areas that that would come to mind rapidly is the use of this technology in vascular imaging.

Certainly venous structures tend to lend themselves well to this.

Tips can be a challenge of course to look at the area of the stenosis.

Typically, we rely on doppler velocities to do that rather than visualization and of course, the aorta and potentially endo stents.

There are some issues with vascular imaging that are challenging, and I'll talk a little bit about that before we end.

But motion is a bit of a problem and something that we'll be working on hopefully to get around as this technology evolves.

Obstetrics and Neonatal Imaging

Other areas that could be potentially interesting are obstetrics.

We have done a couple of early pregnancy cases, and certainly complex fetal anomalies such as cleft palate and other complex facial anomalies might be something that could be nicely investigated with this technology.

One of the things that we also thought about would be the potential for using this technology to look at the neonatal head and a really completely different way of looking at hydrocephalus in in infants.

Gastrointestinal Tract

The GI tract is also an, I think, a fairly obvious area.

Certainly the ability to visualize or fly through, if you will, the common duct or the pancreatic duct, the gallbladder or the gut.

Some of these you've already seen, in the gu tract, hydronephrosis potentially with stones, obstruction, transitional cell carcinomas or even bladder lesions may be nicely evaluated with this technology.

Examples of Virtual Hysteroscopy

As I mentioned, the first thing that really came to mind when we thought about what to do with this technology was so-called virtual hysteroscopy.

Here you can see a polyp, which is sitting in the middle of the screen.

We've just flown right by it.

And again, depending upon how you manipulate this, if you do your own imaging with navigation techniques, you can actually point the arrow around the back of the polyp or beyond it.

Or in this particular case, we're actually pointing the arrow out into the area of the fallopian tubes.

And so these are kind of unique ways of using this technology.

And Dr. Bill Smith in in London has done a fair amount of work with this, and we owe him thanks for allowing us to use some of his nice images here of going almost right out there into the fallopian tube.

Breast Duct Imaging

D as I mentioned in the breast.

As you can see, these are very small structures.

They're only millimeters in size, but the images are actually quite impressive from the standpoint of giving you that same kind of virtual duct topography appearance and the fly through of these structures.

Again, probably this would lend itself well to the evaluation of Intraductal Papillo.

Venous Structures

The veins are relatively easily evaluated with this technology.

The portal veins are quite stable and they don't move a whole lot, so portal veins are easily evaluated.

This is actually in the fly through auto mode, and you can see here that we've actually been able to travel again quite far out into the periphery of this portal venous branch.

And again, if you decided to navigate on your own, you can go into various branches and investigate at will.

We have another patient here, in whom there is obviously a mass like structure here.

And this actually represented an area of portal vein thrombosis.

The hepatic veins are usually fairly large and are easily interrogated as you can see here.

Patients, for example, who have undergone liver transplant, something that we see a tremendous amount of at our institution at in, at the University of Southern California, may for example, develop stenosis in living related donor transplants.

This may be a very valuable way of actually, or a secondary way of looking at areas of stenotic vessels, particularly in these venous structures.

This is a patient here who has had a transplant, but in this particular case, you can actually see the vein dumping into the inferior vena cava.

We directed this, and as you come out of the vein, instead of going outward, we're coming into, and you can sort of see us falling into the larger structure of the inferior vena cava.

The venous structures of the leg, the peripheral veins are also easily evaluated.

Don't get too dizzy on this one.

But both the deep and the superficial veins are very nicely flown through, if you will.

Walls and clots can be visualized quite nicely, and other interesting idea and tips also can be very challenging.

Most of the stenosis that affects the tips will occur in the area of the hepatic veins.

As I mentioned, it's difficult because the only way that we typically diagnose this at this point in time is by looking for doppler evaluation or doppler abnormalities, velocity abnormalities.

In this particular case, you actually have a realtime image showing you the anatomic structure of the tips and the ensuing hepatic vein after it.

Aortic Imaging

The aorta is an easily imaged structure, but as I mentioned, there are a couple of technical challenges, and one of the things that is challenging and we found more in the carotids than in the aorta is motion wall motion.

As you can imagine, if you're going to process an image like this wall motion that's significant can be problematic.

It seems to be less so in the aorta.

One can often follow the aorta down and see the orifices of the vessels coming off of it, including sometimes the renal vessels and of course the iliacs as you go further down.

So a unique way, almost like an ivus where you're looking with an intravascular probe outward from it, without actually of course having to be inter actually performing an interventional procedure.

Obstetric Applications

As I said, we've actually looked at a couple of early pregnancies.

This is just like doing a 3D sweep, so there's no actual added interrogation with ultrasound of these particular patients.

Again, this is something that we're not sure where this will go, but kind of some rather interesting looking images.

Gallbladder and Bile Ducts

Gallstones, I'm not sure that we need gallstone.

We need fly-through technology to see gallstones or to evaluate them.

In our limited time, we've actually not had the ability to image such things as polyps or carcinomas, but I'm sure that the solid masses that affect the gallbladder wall, other things that affect the gallbladder wall may give us an interesting perspective when they're evaluated using this new technology.

The bile ducts, as I mentioned, particularly when they're dilated, are easily seen with this technology.

You can see here that we're actually doing a fly through of a dilated duct.

Probably more impressive than just wandering through the ducts themselves is this particular case coming up here, which actually shows ductile dilatation.

But as you're traveling down the duct, into the area around the pancreatic header, the amary region, you can actually very nicely see that on the horizon.

There is this mass like area which actually represents an am amary mass.

I'm thinking that otherwise would probably be very, very difficult to see.

Certainly a unique vantage point from the standpoint of using ultrasound to get these kinds of images.

Bowel Imaging

The bowel is an area where, again, the, if they are fluid filled, the images are remarkably like those of virtual colonoscopy.

This is obviously small bowel.

You can see the valase quite nicely.

And again, some of the evaluations, if there are polyps or other masses involving the wall of these structures, the imaging can actually be quite impressive.

You can actually, again, go out rather far into relatively small structures.

This is a directed scan.

Here you can actually see that we've managed to interrogate up into the area of the ureter in this particular case out of the bladder.

And so structures at the distal ureter may also be capable of being evaluated using this particular technique.

Challenges and Future Developments

One of the things that I mentioned is that there are some challenges.

This is the inferior vena cava, which is also extremely pulsitile in some patients, and you can see easily here that you get that kind of wall motion.

And this is something I think we're gonna need to work on or may wanna work on in the future.

That is a, that still needs to be investigated as we go forward.

There are, as I mentioned, one of the thoughts we've had about this is for the problem of wall motion is potentially even doing a gated acquisition for the carotids or other very pulsitile structures.

Also one of the other thoughts that we've had is potentially using this in what we've called a transparent mode, where you actually combine fly through with subsurface images.

For example, you would be able to do your virtual hysteroscopy and actually then beyond it, see where the, for example, myoma would be out there sitting in the wall of the uterus.

One of the things that I had actually hoped we would be able to do, and lo and behold, this image just happened to show up here this week, is actually using contrast with reversed polarity.

I know most people who live outside of the United States are used to contrast, here in this country.

Of course, we have issues with it, which largely involve the FDA, but for those of us who do use contrast, it's a very safe procedure obviously, although it is an off-label use.

But in this particular case, one of the thoughts we had was that if you actually took a contrast image, for example, of the carotid artery that you could then construct just like you would with a fluid filled structure, you could then actually go in and reconstruct the lumen of the vessel.

Here you see us rising up in the internal carotid artery out of the common carotid.

You can see both parts of the bifurcation there.

And again, we've directed the image up into the car internal carotid artery itself.

So one of the problems we thought was a technical challenge actually our engineers, I suppose, have managed to overcome that.

But some interesting idea here where you flip the actual polarity of the image to get what you need.

Summary

So in summary, hopefully this is a technology that will yield just more than pretty pictures.

I think the pictures are pretty incredible.

And I think it does have the potential to provide a unique form of imaging with 3D ultrasound.

And in some ways it's kind of, I guess, up to us who may get to use this technology to find out where the eventual role of this technology will be in the future.

Thank you.