0:02

Hello and welcome to Noon Conferences

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hosted by MRI Online. In response to

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changes happening around the world

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right now and the shutting down of in-person

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events, we've decided to provide free daily

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Noon Conferences to all radiologists worldwide.

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Today we're joined by Dr. Javad Azadi.

0:16

He is an academic radiologist

0:18

at the Johns Hopkins Hospital.

0:19

He is interested in hepatic—sorry, hepatic

0:23

steatosis and the metabolic syndrome.

0:26

He is assistant course director for the

0:27

Diagnostic Radiology medical student elective,

0:30

and is a member of the RSNA COVID-19 Task Force.

0:34

A quick reminder, there'll be time at the end of

0:35

the hour for a Q and A session, so please

0:38

use the Q and A feature to ask questions,

0:40

and we'll get to as many as we can before our time's up.

0:43

That being said, thank you for

0:44

joining us today. Dr. Azadi,

0:45

I'll let you take it from here.

0:48

Alright. Welcome, everyone, and thank you for joining.

0:50

My name is Dr. Javad Azadi, and as mentioned, I'm an

0:53

Assistant Professor in the Department

0:54

of Radiology at Johns Hopkins.

0:57

And today we're gonna be discussing

0:59

ultrasound elastography, and how to

1:00

use it to assess hepatic fibrosis.

1:04

I have no disclosures.

1:05

Um, and our learning objectives for today's talk

1:09

include reviewing the liver fibrosis scoring

1:12

systems, of which you may not be familiar with

1:15

because you're radiologists, not pathologists.

1:17

Review the techniques to measure liver

1:19

fibrosis using ultrasound elastography,

1:22

and finally, learn how to interpret and

1:24

report ultrasound elastography results.

1:28

As a review for liver fibrosis,

1:30

remember that liver fibrosis exists on a spectrum of

1:33

disease, from minimal injury to end-stage cirrhosis.

1:36

So you often think about cirrhosis as being

1:40

a nodular liver with contour deformities.

1:43

Uh, you may have portal hypertension.

1:46

And you may see some of these findings in

1:48

a spectrum and attribute it to cirrhosis.

1:50

And it's important to consider that hepatic fibrosis

1:54

is a spectrum, and it's not cirrhosis, because

1:56

cirrhosis reflects the end stage of that process.

2:01

Common etiologies of liver fibrosis include alcohol

2:04

abuse, non-alcoholic fatty liver disease, such as

2:08

steatohepatitis, and then chronic viral infections

2:12

such as Hepatitis C and Hepatitis B.

2:17

There are several widely validated methods

2:21

to score fibrosis using histopathology.

2:24

These include the SAF method, which uses six

2:27

stages, and it's the most sensitive, and it can

2:29

be readily translated into the other scores.

2:32

The reason why this uses six stages is

2:33

because it actually will characterize

2:36

early cirrhosis and advanced cirrhosis.

2:40

METAVIR might be the most widely used system.

2:42

It uses three categories, with a fourth

2:44

category being normal—but mild, moderate,

2:47

severe—with severe representing cirrhosis.

2:50

And then there's the Batts-Ludwig

2:52

category, which is also a four-category scale.

2:55

It has simple definitions based on the degrees

2:58

of interface hepatitis, as well as lobular injury

3:00

inflammation that the pathologist may see.

3:03

And just for a reminder, you may

3:05

see the spectrum includes periportal fibrosis,

3:08

bridging fibrosis, and nodularity.

3:13

When would a clinician want to know

3:16

about a patient's hepatic fibrosis?

3:18

Well, three commonly accepted indications would be

3:21

evaluating the grade of fibrosis prior to initiation

3:24

of an antiviral therapy for chronic viral hepatitis.

3:27

Now we have cures for Hepatitis C, and we have

3:30

several cures, whereas 10 years ago we didn't.

3:33

They want to know how much liver damage has

3:35

occurred and if the patient will benefit.

3:40

Some patients may present to the hospital or

3:42

to their physician with portal hypertension

3:44

or signs of portal hypertension and the etiology

3:47

unknown, and assessing hepatic fibrosis would be

3:50

helpful to assess whether or not cirrhosis

3:52

is the cause of their portal hypertension.

3:54

And then finally, a more commonly used

3:57

application is to monitor hepatic fibrosis

4:00

in response to various treatments.

4:02

Whether they're receiving treatments for

4:03

their hepatitis, or if they're on certain

4:07

chemotherapy agents that may induce fibrosis.

4:11

Now, I'm sure many of you have been asked to perform

4:15

core biopsies of the liver to assist in this process.

4:18

At our institution, we use a

4:20

percutaneous core biopsy device.

4:22

We use 18 gauges.

4:23

You may use larger gauge

4:25

core needles.

4:25

We typically only do a single core for grading.

4:28

You may do more.

4:30

The pathologist is gonna receive that core, and they're

4:32

gonna grade it based on those elements of fibrosis

4:34

that I previously described present in the core.

4:36

Now, the limitations are gonna include under-

4:39

sampling, as in you didn't get enough of

4:41

the elements to get them the correct stage.

4:44

Inter-observer variability.

4:46

One pathologist mild to moderate, maybe

4:48

another pathologist moderate to severe.

4:50

And then the heterogeneous distribution of fibrosis.

4:53

Fibrosis doesn't occur homogeneously

4:55

all at once throughout the liver.

4:56

It is an evolving process, and so you may

4:58

sample a part of the liver that has a different

5:01

stage of fibrosis than the maximum stage

5:02

actually present. Complications of, uh, invasive biopsy

5:07

include bleeding and pain, and I'm sure as many of

5:11

you have experienced, your patients don't like the

5:13

idea of having needles going into them and sampling

5:17

their body.

5:17

It's a very, uh, anxiety-provoking procedure.

5:21

So if we could get away with doing non-invasive

5:23

scoring, I'm sure patients would prefer it.

5:25

Unfortunately, we can't.

5:27

The two primary methods that we use are MRI

5:29

elastography and ultrasound elastography.

5:32

Some of the pros of MRI elastography, which

5:34

I'm not gonna go into further detail, are

5:37

that with our protocols, we're able to assess

5:39

the hepatic fibrosis, the degree of steatosis,

5:42

and if there's evidence of iron overload.

5:44

The downside of our protocol is if there

5:46

is iron overload, it actually makes

5:48

the fibrosis portion uninterpretable.

5:50

It has a very high agreement with biopsy

5:52

fibrosis grades, which again would make the

5:55

biopsies less needed in the workup.

6:00

Because our MRI is expensive as it is, it uses

6:03

a lot of time, and elastography specifically

6:06

needs special MRI elastography equipment.

6:08

It needs an external pulse generator to generate

6:11

elastography pulses that can then be measured.

6:14

Ultrasound elastography, on the other hand, also can

6:17

evaluate fibrosis and to a lesser extent steatosis, although it's

6:20

less agreed upon compared to MRI. It can assess

6:24

the portal vein velocity and direction, which is a

6:26

helpful marker in assessing for portal hypertension.

6:30

It's very inexpensive compared to

6:31

MRI and much more readily available.

6:34

For example, your patient who is bedbound

6:37

in the ICU, you can take this elastography,

6:39

the ultrasound machine, to the bedside where

6:41

they couldn't go bedside with MRI.

6:44

Similarly, you would be able to do patients who have

6:46

contraindications to MRI using ultrasound elastography.

6:50

Cons include it's operator dependent,

6:53

so whether your technologist or you

6:54

are not comfortable or familiar with

6:57

using ultrasound elastography

6:58

may lead to inaccurate results.

7:00

Similarly, there have been studies that show

7:02

that ultrasound elastography may overestimate

7:04

fibrosis in patients who have elevated liver

7:07

function tests, who aren't fasting, or have

7:11

hepatic congestion, which you might see in

7:13

volume overload or right heart dysfunction.

7:15

Now, this wasn't something that I

7:17

appreciated until really diving into

7:19

making this presentation, but there are

7:22

stiffness scores reported for MRI elastography

7:24

and there are stiffness scores reported for

7:26

ultrasound elastography, and they're different.

7:28

But it turns out the reason why is they're

7:30

using different estimates for the stiffness.

7:33

MR elastography is gonna use a shear modulus,

7:36

whereas ultrasound elastography is gonna use

7:37

a Young's modulus, and they are convertible.

7:40

So your MR stiffness scores are gonna be

7:42

typically a third less than what you

7:44

would measure on ultrasound elastography.

7:47

So what is elastography?

7:49

Ultimately, what elastography is, is you're applying a

7:52

vibration and you're going to distort a target tissue.

7:55

In this case, for hepatic fibrosis,

7:57

we're gonna distort the liver.

7:59

Other tissues can be and have been used—

8:01

thyroid nodules, breast tissue, the spleen,

8:05

if you are working up portal

8:06

hypertension, which we do not do here.

8:10

But you distort the tissue.

8:11

You can either distort it using external vibrations,

8:14

and those start at the surface of the skin.

8:15

We see that with MRI, as well as some forms of

8:18

elastography, but we also have a method using

8:21

acoustic radiation force impulse, which I'm

8:24

gonna refer to here on out as ARFI, and those

8:27

will actually start inside the target tissue.

8:29

We then observe the changes to the

8:31

distorted tissue, and we're gonna measure

8:33

shear wave velocity in the target tissue.

8:35

For ultrasound, we're gonna convert that

8:37

measured shear wave velocity, which is measured

8:39

in meters per second, to liver stiffness, which

8:41

is measured in kilopascals using the modulus.

8:45

So what evidence is there for elastography?

8:47

There's been a lot of evidence over the last 10 years.

8:50

These are just two example

8:51

papers and their conclusions.

8:53

The first paper by Oli et al., published in

8:56

2014, talks about using shear wave ELA as a

9:00

reproducible method for assessing liver stiffness,

9:02

comparable to an older form.

9:04

And compared to patients who didn't

9:08

have significant fibrosis and healthy volunteers,

9:11

the values were significantly different.

9:14

An additional paper published in 2014 showed that

9:17

2D shear wave elastography, FibroScan (which is

9:21

another form of elastography), and ARFI (which is

9:25

another form of shear wave elastography) all

9:27

correlated significantly with the fibrosis

9:29

score, with 2D shear wave elastography

9:31

performing the best based on its R value.

9:35

So what ultrasound elastography

9:37

techniques are currently in use?

9:39

Well, we'll talk about two major techniques

9:41

and then dive into the second one.

9:43

The first one is transient elastography.

9:45

The second one is shear wave elastography,

9:47

and that can be subdivided into point

9:49

quantification shear wave elastography,

9:51

and two-dimensional shear wave elastography.

9:54

All three methods are gonna use the Young’s modulus

9:57

to convert that measured velocity and stiffness.

9:59

So how does that work?

10:00

Well, the velocity is measured, it's squared.

10:04

It's gonna be multiplied by the density of the tissue.

10:08

For our purposes, we're gonna

10:09

assume it's one gram per milliliter.

10:11

Then you take that, multiply by

10:13

three, and you get a density.

10:15

And so for all purposes, the shear velocity

10:19

and the liver stiffness are interchangeable.

10:24

The FibroScan (the brand name) uses an

10:27

external vibrating source, so they have a

10:30

five megahertz probe, and it's mounted with

10:32

a vibrating source, which is gonna generate

10:34

elastic shear waves on the skin surface.

10:37

Then you are able to measure shear wave

10:39

velocities in the tissues deep to it, and it's

10:42

gonna be related to the tissue stiffness—higher

10:44

the velocity, the more stiffness. Shear wave

10:47

elastography is gonna use those ARFI pulses

10:50

generated by the ultrasound probe itself.

10:52

And then the speed of the pulse in the measured

10:54

tissue is also gonna be related to tissue stiffness.

10:56

So both methods can be used to generate liver

11:00

stiffness or stiffness of other tissues.

11:03

So a little bit more on FibroScan

11:04

or transient elastography.

11:07

The ultrasound probe is gonna be placed

11:08

over the portion of the right upper

11:10

quadrant that is dull to percussion.

11:12

And the theory here is the dull to

11:14

percussion is gonna be the part of the

11:16

liver with the most hepatic parenchyma.

11:18

And the reason why is these machines

11:20

don't obtain grayscale images.

11:23

You are only getting a shear wave propagation.

11:26

The machine's gonna automatically take 10

11:27

measurements, and it's only gonna report the

11:29

data if it's able to deem it internally valid.

11:32

So either the machine's gonna have output or it

11:34

won't. You won't really be able to troubleshoot it.

11:38

It is a dedicated machine, so you're not able to just

11:41

convert one of your preexisting ultrasound machines.

11:44

Because it's a dedicated machine and it's

11:46

pretty simple to use, it can be used in

11:47

outpatient settings by non-radiologists, and

11:49

commonly you'll see hepatologists performing

11:51

this in their outpatient setting, and then

11:54

they'll have a formal referral to you.

11:56

In radiology, it cannot be used with patients who

11:58

have ascites because the ascites will interfere

12:00

with the measurements, and it doesn't provide any

12:02

other diagnostic information because you don't

12:04

have grayscale or color Doppler capabilities.

12:08

For visualization, this is what a FibroScan

12:10

looks like, and on the right you have two

12:13

examples of the output of the FibroScan.

12:15

The top image showing a liver

12:17

stiffness of three kilopascals.

12:19

The lower showing 40 kilopascals,

12:21

which I'm assuming is just experimental

12:22

because that would be a very stiff liver.

12:26

Point

12:27

quantification shear wave

12:28

elastography is going to use those ARFI...

12:31

301 00:12:32,880 --> 00:12:36,300 ARFI pulses and to generate shear waves in

12:36

a small ROI within the target tissue, you're

12:39

able to use B-mode imaging to visualize

12:43

the liver during these measurements.

12:45

And then the shear wave velocity can then be

12:47

calculated at different locations using this method.

12:50

So this kind of gets over the under-

12:53

sampling of a core biopsy because you

12:55

can take samples throughout the liver.

12:57

In addition, by using B-mode imaging,

12:59

you can ensure where you're measuring—

13:01

hepatic—and it doesn't include bile

13:04

ducts or portal venous vasculature,

13:08

which could change your measurements.

13:14

The other useful

13:15

thing with using this technique

13:17

is that you can get other

13:18

diagnostic information because you still have

13:21

grayscale, color Doppler, and duplex information.

13:24

And that means that you can do this as an

13:26

add-on to your standard liver ultrasound or

13:29

your standard right upper quadrant ultrasound.

13:33

Two-dimensional shear wave elastography is a newer

13:36

method, and it is actually now our preferred method

13:40

of ultrasound elastography here at Johns Hopkins.

13:42

And the previous reference a few slides ago showed

13:46

that it had the highest agreement with tissue samples.

13:50

Multiple ARFI pulses are gonna be sent out over

13:54

a large scale of view, and then you're gonna

13:56

get shear wave velocities over multiple areas.

14:01

You're able to get real-time measurements, and

14:02

you can assess the fibrosis of the tissue in real

14:06

time using a color scale during the scan itself.

14:09

Similarly, you're able to generate confidence

14:11

maps, and so the way that I tell the

14:15

residents and fellows to differentiate

14:17

using 2D versus conventional shear wave elastography,

14:22

pSWE is that 2D is gonna have two circles—

14:26

one with a confidence map and one with the

14:29

actual shear wave velocity—and it's gonna be

14:31

in color, whereas the other will be grayscale.

14:34

And like peak or point quantification

14:39

shear wave elastography,

14:39

it can also be performed at different

14:41

parts of the liver and can be an

14:42

add-on to standard liver ultrasound.

14:46

So what is our technique?

14:49

The patient is

14:51

NPO for at least six hours, and that decreases the

14:54

amount of bowel gas, as well as reducing the

14:57

incidence of overestimation. Preferably, do this

15:00

in an AM study. One reason is it's easier to do

15:04

the study if the patient's been fasting overnight

15:06

than fasting all day because they're cranky.

15:09

The patient should be supine

15:11

or in left lateral decubitus.

15:13

The patient's right arm should be extended.

15:15

We use a C5-1 transducer, and

15:17

we'll use a tissue-specific preset.

15:21

Place the transducer parallel to the rib space.

15:24

We're gonna make sure that we're over the

15:25

liver and we're gonna optimize the 2D image.

15:28

Then we're gonna set cine loops for about six

15:30

seconds and launch the elastography module.

15:34

So whatever company you're using, they're

15:36

gonna have their own proprietary module,

15:37

and you wanna make sure that you have

15:40

adequate training in that specific module.

15:44

You typically are gonna be targeting

15:46

the right intercostal space and

15:48

seeing liver segment seven or eight.

15:51

You wanna keep the liver capsule parallel to the

15:53

transducer surface, and you're gonna place an ROI

15:57

in the center of the image that's about one and a

15:59

half to two centimeters deep from the liver capsule.

16:02

You don't wanna place near a rib shadow,

16:03

you don't wanna place on the capsule, and you

16:05

don't wanna place on non-hepatic structures.

16:08

You'll ask the patient, or your technologist will

16:09

ask the patient, to pause their breathing while

16:12

acquiring the clips—meaning suspend respiration.

16:15

Don't take a deep breath,

16:16

'cause if they take a deep breath,

16:17

the liver may go out of plane.

16:18

And then finally acquire the cine loops.

16:22

With those cine loops, you're then able

16:24

to review them, place measurements, and if

16:28

you have at least three frames of stable

16:31

tissue with high confidence based on the

16:35

confidence map—no rib shadows, no vessels—

16:37

those will be adequate

16:40

measurements to then acquire.

16:43

We generally don't require more

16:44

than two measurements per loop.

16:45

So we'll change our position and we'll obtain 10

16:48

valid measurements as needed, and then we print

16:51

the report. The radiologist will then interpret.

16:56

So this is something I get a lot of

16:57

questions on—for people who don't

16:59

regularly report elastography findings—

17:03

it's just kind of thinking through

17:06

what the different numbers mean.

17:08

You're gonna be given a whole slew

17:10

of numbers with newer machines.

17:11

Median stiffness or median stiffness,

17:15

average stiffness, median velocity, average

17:18

velocity, and IQR, uh, standard deviation.

17:23

And it can be a little overwhelming if

17:25

you're, if you're not just breaking it down.

17:28

The median stiffness or velocity is what

17:30

ultimately we're gonna use to grade the fibrosis.

17:32

And the IQR, the interquartile

17:36

range, describes the spread of measurements.

17:40

We use the interquartile range over the

17:42

median, which can be either stiffness or

17:45

velocity, and that's gonna validate the data.

17:48

If the ratio of the IQR over median is less than 30%,

17:52

if using stiffness, or 15% using velocity, then it's

17:56

deemed quality data and it should be considered

17:59

valid. If the ratio is greater than 30% or 50%,

18:04

velocity,

18:05

remember, the Young modulus has a square

18:08

and then, um, it has a times three, so the

18:13

velocity should be lower than the stiffness.

18:17

The data is considered poor quality.

18:19

However, in the 2015 SRU guidelines, they

18:21

did make a note that the data may still

18:25

be usable if the data obtained is normal

18:28

or low-grade fibrosis based on earlier

18:31

studies using the FibroScan technique,

18:34

which was the older technique that we,

18:36

uh, would use in the hepatology use.

18:38

So I would still report that the data's poor

18:41

quality, but it may still be usable if it's fibrosis.

18:44

But if it's not fibrosis, I would just

18:46

state that the data's poor quality, and

18:50

this is just a visualization of

18:51

what a interquartile range is.

18:54

It's kind of a 50%, 25% below, 25% above the median.

19:00

Um.

19:01

It's just a statistical technique.

19:02

There's nothing special about it.

19:04

You could, uh, manually calculate it if you had to.

19:08

Uh, fortunately, the newer machines

19:10

will actually, um, calculate the

19:12

value for you based on the measurements obtained.

19:17

In 2015, the SRU and a few other organizations

19:21

came with consensus reporting for

19:24

elastography measurements using ultrasound.

19:27

And it was a little confusing

19:28

because it was vendor dependent.

19:30

It was

19:31

method dependent.

19:32

Um, sometimes you weren't sure which vendor you

19:35

were using, so you weren't sure which cutoff to use.

19:38

Uh, the good news is it's been simplified,

19:41

but for historical accuracy, Siemens,

19:46

uh, it used to be less than 1.34 meters per

19:49

second and greater than 2.2 meters per second.

19:53

Philips would be less than 1.37 meters per second,

19:56

or greater than 2.2 meters per second.

19:58

And then using Supersonic Imagine, which is

20:01

the 2D shear wave elastography technique

20:04

available, it was less than 1.5 meters per

20:07

second or greater than 2.2 meters per second.

20:09

So all three agreed:

20:10

If you had a shear wave velocity

20:12

greater than 2.2 meters per second,

20:15

you either had stage four METAVIR, which

20:19

is cirrhosis, or some stages of three,

20:21

which would be advanced fibrosis.

20:22

Whereas if you had the lower end of the

20:25

velocities, then you had, you might have fibrosis,

20:28

but it wasn't deemed clinically significant.

20:31

And then if you were in between, we would describe

20:34

that you would have an intermediate grade of fibrosis,

20:38

and that further workup may be needed

20:39

to determine the actual degree.

20:42

Um, but the good news is,

20:45

as of last month, there was a new consensus—an

20:48

update to the consensus—published in Radiology, and

20:51

it simplified it a little bit, but it also took away

20:54

the correlation with actual pathology grading and gave

21:00

more of a holistic description of what's going on.

21:05

And so it's vendor neutral.

21:06

It's only applicable for, uh, shear

21:09

wave elastography using ARFI pulses.

21:13

And it's really only applicable for patients who have

21:15

viral hepatitis and non-alcoholic fatty liver disease.

21:19

And so now you have some, uh, new numbers

21:22

to think about. If you measure less than five

21:25

kilopascals or 1.3 meters per second—

21:28

and you'll notice that this has both

21:30

stiffness and the shear wave velocity—

21:32

and that's because we've started to

21:34

use shear wave velocity less, and

21:35

actually report the stiffness itself.

21:38

So what you would wanna report is that

21:40

it's a high probability of being normal.

21:42

It's less than nine kilopascals

21:44

or 1.7 meters per second.

21:47

In the absence of other clinical signs, it's gonna

21:49

rule out compensated advanced chronic liver disease.

21:52

But if there are signs—portal hypertension—they

21:54

may need further tests for confirmation and biopsy.

21:59

If the liver stiffness range is between nine and 13

22:02

kilopascals, or 1.7 to 2.1 meters per second,

22:05

and you'll notice all of these, um, are related.

22:08

And that's again through the modulus formula.

22:11

If you get that range, it's suggestive of

22:14

compensated advanced chronic liver disease, but

22:17

you would need a further test for confirmation.

22:19

Generally that means biopsy. If the

22:21

liver stiffness is greater than 13

22:24

kilopascals, or 2.1 meters per second,

22:27

that rules in compensated

22:29

advanced chronic liver disease.

22:30

And if you—we'll just go back a slide—

22:32

if you see that 2.1, that 2.1 is below

22:36

the previous 2.2, uh, recommendation.

22:39

So more patients are gonna

22:41

get a diagnosis of compensated

22:43

advanced chronic liver disease.

22:45

And then finally, if you get a liver stiffness

22:47

rate of at 17 kilopascals or 2.4 meters per

22:50

second for a velocity, it's suggestive of

22:55

clinically significant portal hypertension.

22:57

So not only do they have advanced

22:59

fibrosis, but they likely have cirrhosis

23:01

and a result in portal hypertension.

23:04

These numbers are for viral hepatitis

23:08

and non-alcoholic fatty liver disease.

23:10

And if you are reporting this, it's important

23:12

to put a disclaimer that in other causes of

23:15

fibrosis, these numbers are not validated,

23:17

and so the clinician may have to pursue

23:20

biopsy to actually grade the fibrosis.

23:25

So let's go

23:27

over a few cases.

23:28

Our first case, and this was from several years

23:31

ago, was abdominal pain, history of alcohol abuse.

23:37

So here you have a grayscale image.

23:39

You have an ROI, looks like a hepatic lobe.

23:43

You have a rectangular ROI, no color in it.

23:46

So this is probably gonna be the

23:48

older form of pure elastography.

23:52

And we see a measurement of 1.16, standard

23:55

deviation 0.08 meters per second.

23:58

So that's pretty good.

23:59

You don't see any bile ducts in there, you don't

24:01

see any, uh, portal or any hepatic vasculature.

24:05

So this looks pretty good in terms of measurement.

24:08

So technologists took 10 measurements.

24:11

The average stiffness was 1.08.

24:14

The median stiffness was 1.0.

24:17

You'll note that there is no reporting

24:19

of, uh, the actual kilopascal stiffness.

24:23

It's just the shear wave velocity.

24:25

And that's because the older package.

24:28

And so this is how we reported it.

24:30

The elastography measurements are as follows.

24:33

And this was—I actually manually calculated this.

24:35

The interquartile range is 0.40 meters per second.

24:40

The median velocity is 1.0 meters per

24:42

second, so the IQR over median is 40%.

24:45

So you would have to state that this is indicating

24:47

poor quality dataset for clinical interpretation.

24:50

And again, I put the disclaimer that the IQR

24:55

does not necessarily affect the accuracy if

24:57

the stiffness is less than 7.1 kilo—

25:03

and so the interpretation here would be

25:04

that this is a high probability of being

25:06

normal

25:07

with the 2020 guidelines.

25:11

Alright, case two.

25:13

Indication: elevated liver

25:15

enzymes; evaluate for cirrhosis.

25:16

Patient has a history of alcohol abuse.

25:20

Again, grayscale image, rectangle over

25:23

what looks to be the right hepatic lobe.

25:25

You don't see any vessels in it.

25:27

You don't see any, um, bile ducts, so

25:30

you're confident you're in the right spot.

25:32

You're gonna get good measurements, and even with

25:35

this grayscale image, you can kind of appreciate

25:37

how coarse in the echo texture is of the liver,

25:42

which is a marker of hepatic fibrosis by itself.

25:46

So we take a couple measurements: 2.43, 2.46, 3.08.

25:54

We get a median stiffness of

25:56

2.5, average stiffness of 2.54.

26:00

Going then to the reporting, our IQR

26:04

manually calculates to 0.42 meters per second.

26:08

Our median is 2.5 meters per second.

26:12

The IQR over median is 5%.

26:14

So this is indicating a quality data set for...

26:21

Velocity higher than 2.4 meters per second.

26:24

In the 2015 guidelines, it's higher than, um,

26:28

2.3 meters per second in the 2020 guidelines.

26:32

So this is suggestive of clinically

26:33

significant portal hypertension.

26:37

Case three.

40:40

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40:42

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40:49

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40:52

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