Atherosclerosis Imaging in Real-Time: Bedside and Back To Bench? - SD

Introduction

Hello, I'm Steve Feinstein.

I'm a professor of medicine at Rush University Medical Center in Chicago, Illinois.

And as a cardiologist, my area of expertise is non-invasive imaging and preventive medicine.

These two merge together when we use contrast ultrasound techniques to identify early disease in at-risk patients.

That is patients with early metabolic disease, metabolic disorders, diabetes or proven cardiovascular disease.

So together with non-invasive imaging, ultrasound contrast agents and echocardiography, we are able to identify premature disease in our patients.

Thank you.

Presentation Context

Hello. This presentation was part of a invited lecture at the leading edge conference in 2009 at Atlantic City, New Jersey.

I began the presentation by showing two old friends Barry Goldberg and Harvey fba, both leaders in their field of ultrasound, in radiology and ultrasound in cardiology onto atherosclerosis and imaging.

In real time, I will present a series of slides and movies showing bedside and then back to the bench, contrast, enhance ultrasound and carotid vaso imaging.

We will then move to quantification clinical studies, experimental data and future uses to begin with.

Cardiovascular Disease Epidemic and Technology Needs

Cardiovascular disease is in fact pan epidemic.

What technology are we going to use?

Who's going to rescue and make early diagnosis of patients?

Who will build it? Who's going to pay for it?

And how do patients access healthcare?

Non-Invasive Imaging with Ultrasound

Non-invasive imaging, as shown here by Rembrandt and his early Dutch explorers, ultrasound is portable, goes to the bedside and is quite inexpensive.

As this slide demonstrates, we can image any part of the body, including the carotid, the heart, the kidney, the aorta with ultrasound and contrast can be used to enhance the lumen and the perfusion of tissue.

The next slide is a series of movie slides actually demonstrating the parts of the body that we've imaged with ultrasound in contrast.

So we consider this our cardiovascular prevention center at the core of the ultrasound system.

In the upper left corner is an example of a patient in the different parts of the body and each corresponding movie shows successive imaging of different parts of the body, heart, carotid kidney, the IMT and handheld information systems as long as we can record data from the patient's charts.

Atherosclerosis and Plaque Structure

The next slide is an example of a tumor or atherosclerosis, and as you will note, there's a necrotic core as well as a lining along the lumen surface in this excise crowded plaque from a patient exactly how to plaques grow, what makes them survive.

It is in fact the blood vessels or the vasorum that actually penetrate the wall of the artery into the median and into my surface, providing the tumors or the abnormal growth with new blood vessels As seen in this series of photographs from 1991.

This is from an autopsy sequence where the coronary arteries highlighted here or the lumino Graham is well seen from a silicon high pressure injection.

The plaque is noted here with a piece of calcium in it and as you progress from the left to the right, you'll notice that the vasculature is actually bathing the plaque.

So this is very much an angiogenesis based atherosclerotic tumor.

In this autopsy specimen and early marker of preclinical atherosclerosis is the VAs of his arm as identified by Beaterman.

In these series of quotes on this slide taken from her paper from Ner Etal in 2004, she described that the vassor is actually an early sign of atherosclerosis and occurs prior to the development of IMT thickness.

Contrast Ultrasound Demonstration of Angiogenesis

This slide is our very first example in 2003 of a human carotid artery with contrast ultrasound demonstrating angiogenesis in an atherosclerotic plaque.

As you can see on the surface of the carotid artery, the vasso, his arm lining can be identified.

However, within the tumor itself or the atherosclerotic plaque, you can see evidence of contrast agents circulating.

The next series of slides will show the clinical pathologic correlates to the carotid plaque angiogenesis that I've demonstrated.

This again is a histologic sample from a patient who had a carotid artery atherosclerotic plaque surgically removed.

As you can see on the left part of the slide, that's the lumen and a corresponding necrotic core.

There are cholesterol crystals also seen.

As we begin to look inside the plaque itself into the matrix of the plaque, we can identify many irregularly shaped vasculature.

These are endothelial lined angiogenic vessels.

You can note there are two red cells trapped inside one vessel in the center right screen of note in the upper left corner where it's marked hemosiderin deposits.

You can note there's a brownish stain in the matrix without evidence of angiogenic vessels using the same slide series, but staining with CD 31, which is a mouse auto antibody to human endothelial cells.

You can note there's a growth of endothelial vessels and new vasculature throughout the atherosclerotic plaque.

And an important stain is the hemosiderin stain identifying iron deposits within the plaque.

What this indicates is that when the plaques rupture and the red cells actually extrude from the vaso his arm vessels, the iron within the hemoglobin is deposited in the tumor itself or the plaque and remains there permanently and can be later stained with hemosiderin.

Correlation of Ultrasound and Histology

This graph demonstrates a recent publication in 2007 from the Journal of Vascular Medicine in which we compared and correlated the ultrasound contrast angiogenesis to the histologic examples from the tissue specimen.

What you can see is that the histology correlated very well with the visual quantitation of angiogenesis noted within the specimen in 17 specimen or 15 patients.

Surgical and Imaging Views

This next view is an open re exposure during surgery taken from stroke 2007 and Vince's article.

What you see on the middle left is the common carotid then bifurcating into both the internal and the external carotid.

Please note the surface of the artery itself is filled with small wisp like vessels.

These are in fact angiogenic vessels.

And another view from the same paper in 2007 reveals a standard carotid imaging in A then B with color doppler and C with contrast enhanced ultrasound.

Note that within the plaque itself are the small microspheres And finally from the same paper of stroke 2007, another example of the contrast enhanced carotid in A and in B, you can see the micro vasculature and see of course at the time of surgery.

Patient Examples from Rush University

This is a patient taken from our laboratory at Rush University Medical Center in Chicago.

It's a patient who has a graft in the carotid artery.

What you'll note is there's very little angiogenesis within the dark luminal structures.

These in fact represent the arterial grafts.

However, on the next slide, proximal to the bifurcation, you can see vast amounts of angiogenesis lining the arterial surface of the artery while the contrast flows through the lumen itself.

The next slide is courtesy of professor Maori and Stefano choline Milan, Italy.

It's a patient with Taaka ya's disease and notice that the inflamed arterial wall is tremendously vascular after the contrast injection.

By the way, all these contrast injections are injected through a peripheral vein in the arm circulating through the right heart lungs, ultimately to the left heart and then to the carotid artery.

So none of these are are arterial injections, but venous injections requiring only a half milliliter of a contrast agent.

In this slide, you can note that the inflammatory wall is filled with vasculature consistent with the inflammatory nature of Taki's disease, and in fact looks very similar to the previous images I've shown you with atherosclerosis.

And in fact, the next slide courtesy of Hans Peter Wescott from Hanover, Germany.

What you'll notice is that the plaque can be seen intruding upon the lumen, but you can also notice there's an external surface to the plaque, which is positive remodeling as well as negative remodeling.

And in fact, the atherosclerotic plaque is filled with contrast agent signifying that the vessels are within this tumor or atherosclerotic plaque.

The next image is a patient of mine whose 53-year-old diabetic gentleman not on a statin.

On the left in real time, you can see the common carotid artery.

You can see the contrast entering.

And if you will note at the bifurcation, there's an exceedingly bright signal which indicates the vaso arm over the bifurcation.

The image on the right is eight months later after placing the patient on a statin to reduce the inflammatory response of atherosclerosis to the arterial wall.

As you note, when we approach the bifurcation on the right, the vessel that was so apparent on the left is now only a remnant.

This is probably the first indication of regression of angiogenesis seen in a patient.

This was published in 2006.

This patient example was one week ago in our laboratory.

It's an asymptomatic patient seen for preventive screening.

As you'll notice on the posterior far wall, the IMT can be seen as normal.

However, as we approach the bulb, there's IMT thickness.

And if you look carefully, in fact, in one of the plaques seen at the bulb on the far wall, there's actually vasculature as we move towards the bulb in the same patient.

You can note that the far wall plaque identified at the bulb is in fact quite vascular as well as thickened.

And the final image in this sequence shows that the plaque not only intrudes into the lumen and is vascular, but also extends outward or caused positive remodeling.

So the tumor or plaque actually extends both inward and outward and is readily seen in this example.

Quantification of Images

Now what about quantification of these images?

To date, most efforts have been simply qualitative.

Working with Dan Adam from Haifa, at the Teknion Institute in Israel, Dan has developed an in vitro test model where we can actually design the carotid artery and the vaso arm.

The next series of slides will show our results.

What you see on the left slide is flow through the plastic tubing in the lumen, and if you notice in the upper left, you'll see the small vessels flowing through the vaso.

In a series of calibration studies, we noted that as the contrast concentration increase, so did the video image in both the lumen and the vassor.

As we began to develop this model, we are now using 3D imaging of the vaso and lumen.

When we move into clinical studies, we have also performed calibration studies.

What you see in this slide is an intravenous injection of 0.5 1.0 and one point 0.5 milliliters of an ultrasound contrast agent in the patient.

The lumen is increasingly bright and the vasso arm as identified by the green and blue regions of interest are also increasing in brightness.

And if you look at the graft, you will notice that as the luin increases in brightness, so does the vavo.

Very similar to the in vitro tube study.

Furthermore, we are looking at ways to quantify the vasorum.

We have identified a region of interest between the lumen and the intima media, and that considered a standard vasorum baseline or normalization.

And then we have a region between the green line, as you see, and the blue line, which includes the vasorum.

So in order to do this, we actually developed a ratio of adventitial intensity to lumen intensity.

Based on this data, we have looked retrospectively at around 159 patients from our laboratory.

What we found is that patients who had significant more angiogenesis had in fact an increased incidences of heart attack or stroke.

Now, this represents a retrospective study correlating the presence and amount of angiogenesis in our patients.

It does not represent a prospective study at this time.

Animal Models

Furthermore, we are looking to develop animal models that mimic the human atherosclerotic condition.

We've been working with the researchers at the University of Wisconsin involving the Vasorum activities seen in the rappa familial hypercholesterolemic swine model.

What you see in the upper right corner is an insert of the FH swine and in the lower left two boxes, the femoral arteries and the histology of the femoral artery on the right, an angiographic view.

And below that, the ultrasonic view of the femoral artery.

What you will see now on the right is a real time image of an contrast injection, intravenous injection in the FH swine, the luminous highlighted.

But what you'll notice above the lumen are presence of angiogenic vessels filling the wall indicating atherosclerosis.

Simply seen in this slide, we then began to develop a serial quantification of the vaso in the FH swine at five weeks, 13 weeks, and 43 weeks.

Please note the VAs of his arm above the lumen was poorly seen at five weeks, minimally at 13, and was significantly seen at 43 weeks.

Conclusions and Future Directions

In our conclusions then the contrast enhanced imaging is a unique platform to study atherosclerosis, and the rappa pig model apparently is a good place to begin this investigation.

Future issues will resolve the difficulties we currently have in plainar imaging with 2D, and what we prefer to image is a volumetric analysis of the carotid artery, the lumen, and the vaso arm as seen in this slide.

Ultimately, the 3D representation as shown here will show the lumen, the bifurcation, and the adventitional structures in one volumetric analysis.

Finally, site-specific drug delivery.

Therapeutic systems are being developed.

The micro spheres carry agents and with the activation of ultrasound will deliver at certain locations their payloads.

A simple slide demonstrates the agent is mixed with the microbubble and the ultrasound energy, then destroys the microbubbles and delivers the agent at sites.

Thank you very much.