Serial Sonographic Assessment of Lymphedema/Fibrosis with Shear Wave Elastography - HD

Introduction

Hi, I am Arthur Fleischer, chief of ultrasound at Vanderbilt University Medical Center in Nashville, Tennessee.

Presentation Topic

This talk is about the use of ShearWave elastography in evaluating patients with lymphedema and fibrosis.

This presentation describes our initial data in patients who have undergone radiation therapy for oral facial cancer in the assessment of lymphedema and fibrosis using ShearWave elastography.

Acknowledgments

I'd like to acknowledge my co-authors, venina Eva Paha, which she is the sonographer involved. G ding, who is the nurse practitioner researcher, and Barbara Murphy, who is the oncologist.

This is a grant supported by NCI.

Objectives

The objectives of this talk is to present some very preliminary data on changes in skin, muscles, soft tissues of the neck and face in a longitudinal assessment with a baseline study.

And now at three months, this is part of an ongoing project where we will be seeing the same patient at three months, six months, nine months in a year after undergoing chemoradiation for oral facial cancer.

We will correlate the SWE with the clinical assessment of lymphedema.

Lymphedema is assessed from grades A through D, with D being the most severe.

We will also be looking at changes in thickness in skin, assessing skin to bone measurements and muscle measurements.

We will assess the accuracy and repeatability of SWE measurements and determine how to improve the accuracy and reliability of ShearWave elastography.

Background on Tumors and Lymphedema

Basically, tumors have very abnormal vessels, and the abnormal vessels show large gaps in the endothelial gap junction, which allow fluid to escape into the interstitium.

In addition, the lymphatic drainage inside tumors is impaired, so you have development of basically lymphedema.

This has implications as to not only the symptoms of the patient, but also the ability to have drug go into the tissue and be effective if the interstitium of the tumor contains acidic fluid.

This degrades the medication once it goes in across the gap junction.

Patient Example

This is a patient who has lymphedema on the right, in the right cheek area.

This is a patient that has, as you can see, cancer, cancer of the tonsil, stage four that was treated with radiation therapy and represented with right cheek lymphedema.

These patients have typical lymphedema type patterns and about 60% of all patients that are treated develop lymphedema.

Lymphedema is an abnormality in the lymphatic system in the dermis and the sub dermis layers.

As this diagram shows, one has arteries, veins, capillaries in the dermis, and then in the sub dermis there is some buildup of fluid giving lymphedema.

Lymphedema itself is very commonly seen in patients that have cardiac dysfunction, so-called third spacing.

It can also be seen in patients that have had breast cancer surgery due to lymphatic obstruction.

For some reason, patients that have radiation therapy are prone to develop lymphedema, and there are of course many non-specific causes as well.

Study Purpose

So this study was a study that continues to look at the ability of ShearWave elastography to quantitate lymphedema and fibrosis in these patients that have oral facial cancer.

The need is to assess the extent and changes in the underlying skin and muscle fascia, and also to try to find ways to improve the accuracy of ShearWave elastography.

Assessment Sites

In this study, five sites were chosen for assessment of lymphedema and changes in thickness and muscle thickness, and they're shown here.

The first is the maxillary prominence where we also measure skin to surface to bone distance.

The second is in the middle mandible area where skin surface to bone is quantitated.

The third is the submental area where skin to surface to bone, skin surface to muscle.

The fourth and fifth are along the line of the sternocleidomastoid muscle, one high and basically one low where we assess skin surface to muscle thickness as well as SWE.

The SWE measurements are duplicated in these sites to determine the measurement error.

Clinical Evaluation Scheme

Clinically edema is evaluated using this scheme, which has been described by our group where A is basically no lymphedema.

B is visible soft tissue edema, that's reducible, so-called pitting edema.

C the edema is non reducible.

D is very firm with increased density, decreased compliance, basically representing fibrosis.

And the above grades can be evaluated and quantitated mild, moderate, or severe.

Methods

So our methods in this ongoing project, as I mentioned, are to do a baseline study at three months, six months, nine months, 12 months in patients undergoing chemoradiation.

The SWE is performed using a Phillips Epic scanner with a C five two transducer and a gel standoff.

And as we said, five sites per side of face are obtained.

And in several of the sites, the SWE measurement is duplicated in three of the five sites.

As of the data I show here, we have 15 patients that have three months follow up.

Elastography Techniques

So we started this project using strain elastography, and as you know, pressure is applied in strain elastography, and you're quantitating changes in thickness with pressure as opposed to ShearWave elastography where a beam is generated and you're looking at the velocity propagated at 90 degrees to that beam.

In ShearWave elastography, the amount of stiffness or velocity can be quantitated in kilo pasquale or in meter per second.

Strain Elastography Examples

This is an example of a patient that has left sided lymphedema, and I hope you can appreciate on the picture of the edema around the jaw area in this patient.

I wanna draw your attention to this strain Elastography, which I can show you here, has a red signal, red being soft, and if you compare that to the opposite side, you can see that there is a blue signal, which is indicative of hardening of that area.

This is another patient that has actually fibrosis, and as you can see the right side, the left side here is actually more than the right side.

And these are strain elastography showing a big difference in the normal side and in the abnormal side.

In this patient, which I showed you at the beginning of the talk, that has lymphedema on the right, right here, you can see a big difference in the strain ELAs grams.

But the problem with the strain ELAs, it's very hard to quantitate.

And this patient with severe fibrosis, as you can see here, there's a big difference between the normal side and the fibrotic side with more blue colors indicative of a very hard skin surface.

Results: Thickness Measurements

Now, quantitating the measurement differences in the thickness again is an ongoing project, but our initial data shows a increase relative increased thickness in the more severe type Bs.

As you can see from this box diagram, there are other areas that we have looked at the cheek, the submental, and the neck area, which also show increased thickness in areas of lymphedema and fibrosis.

And this is a comparison of right versus left in these patients.

Results: Shear Wave Elastography

As far as ShearWave elastography, this is our two of our first patients in our study, and we can see that in this patient who has a type D amount of lymphedema, there's a very high velocity rate in this patient who has a B or C abnormality.

There also is a very high number, but not as high as the first patient who has a type D amount of lymphedema.

And here's an image from that first patient who had severe fibrosis.

As you can see, there's a standoff area related to the gel pad.

The skin is very nicely depicted, and in this box, the velocities are extremely high.

As you can see from that image, this patient has a B2C amount of lymphedema.

And as you can see here, this patient has also elevated SWE values.

Now, based on our initial data, five sites measuring skin to bone or muscle thickness, there clearly is a trend to increase thickness relative to the severity of lymphedema.

However, some of these differences are within the measurement error.

These are the SWE values.

After three months of treatment in 15 patients, in three out of 15 patients, there was no lymphedema, and the SWE value averaged 2.9 meters per second in two patients with a type lymphedema, as you can see, the number is elevated at 3.5 and B patients, there are seven of them.

The measurement of SWE values was elevated, and c it was also elevated.

And in the one patient with D the average measurement was elevated, and we're in the process of looking at the data from each site comparing right to left.

Summary

So in summary, we see that there indeed is a trend toward increased thickness in the skin as well as the muscle in patients with lymphedema.

And we're also see an incremental increase in the SWE values.

The amount of increase, however, is relatively small and in some cases probably within measurement error.

Future Questions

So we still have many questions to answer.

How do we best detect lymphedema before it becomes fibrosis?

The idea is to try to get detect lymphedema early so it can be treated and certainly way before it becomes fibrotic.

Are there ways to optimize SWE, new transducers may be very helpful.

Does SWE improve with successful treatment?

This is kind of a side project that we're looking at.

What is the magnitude of the measurement error?

We are beginning to quantitate that.

What is the correlation between thickness and SWE?

In other words, do the SWE values go up when the patient's thickness changes?

And what are the therapeutic implications for lymphedema fibrosis assessment with SWE?

Closing

I wanna thank my coworkers, who are shown here for an initial evaluation of this data, which is as I say is an ongoing project.

Thank you.