0:02

Hello and welcome to Noon Conferences hosted by MRI Online.

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In response to changes happening around the world

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right now and the shutting down of in-person

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events, we have decided to provide free daily

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noon conferences to all radiologists worldwide.

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Today, we are joined by Dr. Bhargava.

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Dr. Bhargava is a professor of radiology at the

0:21

University of Washington in Seattle, Washington.

0:25

His current work is focused on data analytics, radiology

0:29

operations, organizational psychology, and leadership.

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A reminder that there will be a Q&A

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session at the end of the lecture.

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So please use the Q&A feature to ask your questions,

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and we will get to as many as we can before our time is up.

0:43

That being said, thank you all for joining us today.

0:46

Dr. Bhargava, I'll let you take it from here.

0:49

Good morning.

0:50

It's good morning here in Seattle.

0:52

I know people from around the world have joined in.

0:54

Thank you for inviting me, Dr. Collins.

0:56

I saw you as one of the attendees.

1:00

So, in the next hour, we will talk about imaging

1:04

complications of liver transplantation and sort of an

1:07

allied topic, which is how to help your surgeons

1:11

by providing relevant information when

1:15

a surgical liver resection is being planned.

1:17

I will try to simplify these topics.

1:20

Liver transplantation can seem like a daunting topic.

1:24

If the institution you work with

1:27

doesn't do a lot of liver transplants, or if somebody

1:31

really hasn't simplified this for you, it looks daunting,

1:33

but it's actually very algorithmic.

1:36

We'll go through an algorithm of how to manage liver

1:38

transplant complications at the end of this talk.

1:42

All right.

1:42

So, with that, let's begin.

1:44

Meanwhile, you can type in your questions

1:47

in the Q&A; I'll take them at the very end.

1:50

So, what are we going to do in the next

1:53

30 minutes or so for liver transplantation?

1:56

I'm going to focus on orthotopic liver transplantation.

1:59

First, we should know what the normal

2:00

postoperative imaging appearances are.

2:03

Then we'll talk about complications, imaging

2:06

findings of complications, and then understand

2:09

how to integrate the role of imaging in the

2:12

management of liver transplantation complications.

2:17

So as background, uh, liver transplantation is,

2:20

uh, the treatment of choice for end-stage

2:23

acute versus chronic, um, liver disease.

2:26

As time has gone on, um, the graft survival

2:30

and patient survival rates have improved.

2:33

Uh, and they've improved mainly because of improved

2:35

surgical techniques, better immunosuppression, and

2:38

frankly, we have gotten better at imaging in the early

2:41

diagnosis and treatment of, um, transplant complications.

2:45

Um, surgical technique.

2:47

Um, so there's multiple anastomoses.

2:52

Suffice to know that most of the anastomoses are end-to-end.

2:58

But when you have a CBD that's too small,

3:02

diseased or even absent, then you're left with

3:05

no choice but to do a choledochal jejunostomy.

3:08

Now, as you can imagine, if instead of doing an end

3:11

to end donor recipient CBD anastomosis, you just

3:15

stick a loop of jejunum up to the hepatic hilum,

3:21

you have all the jejunal contents basically bathing the

3:25

bile ducts, and that leads to increased chances of

3:28

infection, bleeding, um, and even anastomotic dehiscence.

3:34

So, a couple of interesting things

3:36

about, um, arterial anastomoses.

3:38

Now, the important thing to understand is that, um, the,

3:42

the, the caliber of the arteries that are anastomosed,

3:46

donor versus recipient, is almost never the same.

3:50

So you have to have, um, a technique in

3:54

which how you're going to anastomose two

3:56

arteries that are of different caliber.

3:58

So there's different ways of doing this.

4:01

Um, and there's some fancy names right there,

4:03

but, uh, suffice to note that, uh, what the

4:07

names are and the techniques are not as much

4:10

as important as, as the imaging appearance.

4:13

So if you look at this image, um, the

4:16

surgical clip, which is that bright dot.

4:18

That tips you to that this is the

4:20

site of the arterial anastomosis.

4:22

Now if you look at the arterial

4:24

anastomosis, it looks bulbous.

4:27

And this is the normal appearance of the fish

4:30

mouth anastomosis, so it's created into this

4:33

wide, wide, wider shape at least on one side.

4:37

Um, and then it's anastomosed and the,

4:39

and the, and the important thing is to

4:40

not confuse this with a pseudoaneurysm.

4:43

I will show a good example of

4:44

pseudoaneurysm later on in the talk.

4:46

And the reason this is important is that

4:48

a fish mouth anastomotic appearance is

4:51

normal; nothing needs to be done about it.

4:54

A pseudoaneurysm, on the other hand,

4:57

when they form, they produce no symptoms.

4:59

So, um, again, symptomatically you can

5:03

distinguish between the two, but a pseudo

5:05

aneurysm has a weak wall and it can rupture.

5:08

And if, and if a pseudoaneurysm ruptures,

5:11

uh, the bleeding can be pretty bad.

5:13

And the patient is at risk of dying.

5:15

So if you see a pseudoaneurysm,

5:18

you have to treat it.

5:19

But again, we don't have to treat a fish mouth

5:21

anastomosis, which is what this is, right?

5:24

So don't call it a pseudoaneurysm.

5:26

This is classic for fish mouth.

5:27

If you've seen one, you've seen them all.

5:29

Um, you will occasionally come, come, uh, come

5:32

across people who read this as pseudoaneurysms

5:35

because they haven't seen this appearance before.

5:42

So, in terms of surgical technique, most of the anastomoses

5:46

that I was describing to you are end-to-end anastomoses.

5:50

A short segment portal vein thrombosis

5:53

is not an absolute contraindication.

5:56

You can always do a jump graft.

5:58

Um, the, the biggest, um, impact of IVC, um, surgical

6:05

technique innovation was in the IVC anastomosis.

6:08

So in the past they used to do an end-to-end anastomosis.

6:12

So what they used to do is they used to go deep inside.

6:15

the, the recipient, uh, cut, um,

6:19

a portion of the IVC, removed the liver out.

6:21

Now, as you can imagine, the, uh, IVC was pretty deep.

6:25

It was hard for the surgeon to get in.

6:28

There was a lot of bleeding and there were two anastomoses.

6:31

Now, what the surgeons, uh, figured out

6:33

was that they don't really have to cut at

6:35

these two points and transpose the liver.

6:38

What they can do is the piggyback technique.

6:40

So in this piggyback technique, what you

6:42

do is you just have one anastomosis.

6:45

You leave the native IVC in there.

6:48

You just stick the, the, the

6:50

recipient IVC on top of each other.

6:52

Now what that does is that it

6:54

decreases the risk of bleeding.

6:57

All surgical complications happen at the anastomosis.

7:00

This is just a buzz, you know, sort of a,

7:03

some buzzwords that you just have to remember.

7:05

Uh, you know, in, in any post-surgical anatomy, mostly

7:09

complications happen at the surgical anastomosis.

7:11

So you just go straight to the,

7:13

uh, look up your operative report,

7:15

go straight to the anastomotic sites, and that

7:18

is where you'll have, um, the complications.

7:21

So, in the piggyback technique,

7:22

they just put it on top of each other.

7:24

It actually shortens the surgery by up to an

7:27

hour, so everybody's happy it's a shorter surgery.

7:30

You decrease the number of anastomoses by one,

7:33

which means a 50 percent reduction in the anastomotic

7:35

sites in the IVC, and there's decreased bleeding.

7:39

So, it's a win-win everywhere.

7:41

Now, the way it works is that the inferior end

7:43

of the IVC is kind of tied off, so a little

7:46

bit of thrombus can actually form in there,

7:49

and this is how it looks in the operating room.

7:51

I got this from one of our transplant surgeons.

7:54

This is a liver being harvested.

7:56

Um, and this is how it looks like.

7:59

This is the recipient IVC.

8:01

This is the donor IVC.

8:02

They're just pasted on top of each other.

8:04

So when you look at it at the right

8:06

image, it looks like there's two IVCs.

8:10

So what can we do on imaging?

8:11

So we have lots of imaging modalities right now.

8:14

The vast majority of transplant imaging is

8:18

actually done, um, on ultrasound because

8:21

ultrasound is a screening modality.

8:23

Um, it's cheap, it's, it's easily

8:26

available, and it's a screening test.

8:28

So you, you kind of do the ultrasound and

8:31

you figure out where the problem is, and then

8:34

you can decide to do CT or MR, rarely PET.

8:38

Um, and that, so it's a good place

8:40

to start, uh, with ultrasound.

8:42

Some physics, I always like to have at least one or

8:45

two, um, things about physics in every lecture.

8:49

Um, so you want to make sure that your settings are

8:51

right, and these are the settings that you need to employ

8:55

with ultrasound.

8:57

With CT, you want to make sure that you have

8:59

thin sections in case you need to look at

9:02

the arteries a little bit more carefully.

9:04

A little bit thicker sections for

9:05

portal venous phase is just fine.

9:08

And you want to look at the vasculature.

9:10

You want to look at the bile ducts.

9:12

You want to look at the liver parenchyma, and you want to

9:14

look, um, you know, elsewhere around the liver, especially

9:18

so if you actually work in a transplant center, like

9:22

I do, um, you'll see a lot of requests come through,

9:26

uh, with the history being given: rule out rejection.

9:29

Well, I can't rule in or rule

9:31

out rejection based on imaging.

9:33

That's the first thing we have to understand.

9:35

Um, they're writing that in the history

9:38

because that's what they're worried about.

9:40

Now, um, rejection, as you,

9:43

as you know, can be acute or chronic.

9:45

It can be very nonspecific, both

9:47

clinically and with lab findings.

9:49

And we can't really exclude, um, rejection on imaging.

9:53

So what are we, why are we doing this study?

9:55

Well, we're doing this study mainly because

9:57

if we can see if there's any other causes

9:59

that might explain the lab findings.

10:02

Are there other findings that might explain

10:04

why the liver transplant is not doing well?

10:07

So it's actually a study of exclusion in some way.

10:09

If you want to make a diagnosis of, uh, of, uh,

10:13

of rejection, you actually need to do a biopsy.

10:18

So moving on to vascular complications.

10:21

Um, these are the big ones, um, because these are,

10:24

um, um, the complications that actually lead to the

10:28

death of the transplant, and the hepatic

10:31

artery complications are way more important than the

10:34

portal venous and the hepatic vein complications.

10:36

So let's recap what we've learned so far.

10:39

So, um, anatomy, you have to know your surgical technique,

10:43

you have to know your fish mouth anastomosis,

10:46

you should know what the piggyback anastomosis looks like.

10:48

And you have to know that you can't diagnose

10:51

rejection on imaging; you can suspect it.

10:54

But at the end of the day, you'll have to do a biopsy.

10:57

And if there's one thing you need to know

11:00

about liver transplant complications,

11:03

those are the hepatic artery complications.

11:06

So I have this little joke that when I present this lecture

11:10

to, um, our residents in the pre-COVID times where I

11:14

would go into the lecture hall, they would be, they would

11:16

be sitting, and I would start talking from as soon

11:19

as I would enter the hall, like, what is the one thing

11:22

we need to know about liver transplant complications?

11:25

And then for those people who had heard this lecture

11:27

before, they would say hepatic artery complications, right?

11:30

So, um, and then we would laugh over it

11:32

because I haven't even plugged in my USB.

11:35

And the idea about cracking that joke is I want our

11:38

residents to know that when they're alone at night, or if

11:41

they've not seen a liver transplant in a while, um, they're

11:45

not going to hurt a patient at night if they can only

11:50

look at the hepatic artery and make sure it's doing okay.

11:54

If you're alone, you have no help, um, it's in the

11:57

middle of the night, and you make sure the hepatic artery

11:59

is okay, you've nailed the case because everything

12:02

else can be taken care of, uh, in a couple of hours

12:06

when maybe somebody with more experience shows up.

12:09

Now to, to look for hepatic artery complications,

12:13

um, the most important thing is to know your normal.

12:16

So if you can just say all these things are normal, normal,

12:20

normal, If you have a normal job, then that's like 80% to 90%

12:23

of the job, and when it's abnormal, you, you need

12:27

to know whether this is a vessel in transition because it's,

12:33

it's just had a new transplant and will it normalize over

12:36

time, or is this an emergency right so step number one.

12:40

you know, up to, you know, a high percentage,

12:43

the vast majority will have a normal flow.

12:46

So what is a normal flow in the hepatic artery?

12:49

So any artery in the body, and this

12:52

is like a basic Doppler principle.

12:54

So any, any important organ has to have

12:58

continuous flow throughout the cardiac cycle.

13:01

Now, you cannot have even for, you know,

13:03

a millisecond, um, or a portion of a millisecond,

13:07

no flow in any critical organ in the body.

13:09

So, um, when you look at the hepatic artery, there

13:12

is continuous flow throughout the cardiac cycle.

13:14

That's very important.

13:16

Um, there should be a very brisk upstroke.

13:19

So from point number two to point number one, that

13:22

line is not completely vertical, but it's almost

13:25

vertical, and that's the normal hepatic artery.

13:28

Just to give you an idea of how steep

13:30

that slope is, it's almost vertical.

13:33

It takes 0.08 seconds for the flow to reach peak systolic velocity.

13:39

So it's nearly vertical.

13:41

And if somebody asks you what's the RI, the RI

13:44

value of something and you just blurt out 0.5 to 0.8,

13:47

that's actually true for most vessels.

13:50

So there's nothing, uh, abnormal, uh,

13:53

or something else to remember about the RI values, 0.5 to 0.8.

13:58

Now, if your RI values are not in

14:00

this range, having a higher than

14:04

0.8 RI value is actually better than having a slightly

14:08

lower RI value because the lower RI value over time

14:12

means that that transplant will have more complications.

14:15

So let's talk about what goes wrong in the hepatic artery

14:18

now that we know what the normal hepatic artery looks like.

14:22

So, um, this paper listed at the bottom, and there's

14:26

one other with the immediate post-operative

14:29

complications in liver transplant and radiographics.

14:33

They're definitely worth going through the images

14:36

that they show, and that'll show you that in the

14:38

first 72 hours, the recipient's body has

14:42

been used to having a cirrhotic liver for a long time.

14:46

And suddenly now there is a normal

14:48

liver of a young patient, right?

14:50

Uh, that's been stuck on the IVC.

14:53

Uh, it takes a while for the recipient's body

14:56

to actually accommodate that new healthy liver.

15:00

So what happens is that anytime there's an

15:03

astomosis, there's edema, and that can lead to a kink.

15:07

Um, and those will resolve, uh, most of these findings will

15:11

resolve over 72 hours, um, and again, higher, uh, RI values,

15:16

uh, very common in the immediate post-operative setting.

15:19

So, uh, unless you have, uh, no flow or

15:23

severe stenosis in the hepatic artery,

15:26

um, most of the other findings that you'll

15:29

see will actually resolve over 72 hours.

15:32

And these are followed very closely.

15:34

Uh, all the transplant surgeons are familiar with it.

15:36

Um, and so, uh, but again, if you have a new

15:41

liver transplant and you see, you know, RI values of

15:44

0.9, don't just say, "Oh, this is acute rejection."

15:47

Remember we can't really, um,

15:49

diagnose rejection on imaging alone.

15:52

So this is a good example, you know, immediate

15:56

post-operative, um, there's, you know, RI

15:59

value of one, there's, uh, you know, a little flow,

16:04

and then as soon as you wait, uh, a couple of days,

16:07

and this is a scan like six months later, but this resolved

16:10

within 72 hours showing a normal, uh, spectral waveform.

16:15

Now, uh, hepatic artery stenosis, what does that look like?

16:19

Um, so, again, this is a, this is a classic, this

16:23

is an ultrasound classic, Tardus Parvus waveform.

16:26

So where do you see Tardus Parvus waveform?

16:28

Um, after the anastomosis, after the stenosis.

16:34

So when you have a hemodynamically significant stenosis,

16:39

beyond that, you see this Tardus Parvus waveform.

16:42

What is a Tardus Parvus waveform?

16:44

It's got a very slow systolic upstroke.

16:46

Now notice that almost straight line

16:49

upstroke that I was talking about.

16:50

Now how slow, uh, that slope has become.

16:53

That arrowhead that you can see, it's a, it's a very,

16:56

uh, shallow slope compared to how steep it should be.

16:59

And the velocities are pretty low.

17:01

So once you see a Tardus Parvus waveform, uh, that tells

17:05

you that there is a hemodynamically significant stenosis.

17:09

Proximal to it, right?

17:11

So you can find a vessel if it, if a vessel shows normal

17:13

waveform and at one point it shows Tardus Parvus waveform,

17:17

you know that the stenosis is somewhere in the middle.

17:21

So this is how it kind of looks on an angiogram.

17:24

Um, so the surgeons actually, um, will have a pretty

17:29

good idea of, uh, whether they are going to expect

17:32

this or not in the immediate post-operative setting.

17:36

And the reason is because they know how, um,

17:39

how, how much of a mismatch they had when

17:41

they anastomosed, uh, the hepatic arteries.

17:43

They are aware of, um, you know, if the

17:47

anastomotic suture line wasn't great or whatever.

17:50

So they're aware of that.

17:51

So then they have to decide what are they going to do.

17:53

In the vast majority of cases, when you have a

17:56

stenosis, you can get by with an angioplasty or stent.

17:59

Um, and if there's a thrombus, you can lyse it,

18:02

but occasionally, you may need to do a surgical revision.

18:06

Now this is, uh, this again, this is a good

18:09

example of, um, hepatic artery stenosis.

18:13

Now, um, if you get something like this, um,

18:20

the surgeon decides whether it'll be a CTA that's done

18:24

next or a catheter angiogram that's done next.

18:27

So leave it up to the surgeon to decide

18:30

what modality should be done next.

18:32

Now, so, this is something really interesting

18:35

that I actually learned from my IR colleagues.

18:38

So, you can have a Tardus Parvus waveform but

18:41

that always doesn't mean that somebody needs

18:43

to jump in and do, do, do a recanalization.

18:48

And this...

18:50

So in the chronic stage, uh, you can have a Tardus Parvus

18:54

waveform, but look at the, the arrows show like those

18:56

wispy collaterals that you almost never see on a CTA.

19:00

I've never seen these, um, and you

19:03

see them really well on an angiogram.

19:05

So if, if the vessel is collateralized and there's, there's

19:09

good caliber distally, you don't need to do anything.

19:12

There may be Tardus Parvus waveform, um,

19:14

but, but, you know, there's been enough

19:16

compensation that you can just watch them.

19:18

So we have a couple of patients in our

19:19

system who have this kind of appearance.

19:22

They consistently, when they come for their

19:24

annual checkups, they have Tardus Parvus

19:26

waveform, but they're doing just fine.

19:27

So, Hepatic Artery Thrombosis.

19:30

Now, this is what, on call, this is the

19:33

one case that if you, if you mess up, uh,

19:36

everybody is going to be very unhappy with you.

19:40

When people roll out in the morning,

19:41

if you're taking call all by yourself.

19:44

And so hepatic artery thrombosis,

19:46

how do you, how do you diagnose it?

19:47

So if you, if you go to the porta hepatis and

19:50

you see the portal vein and anterior to the portal

19:52

vein, you do not see your hepatic artery.

19:56

You get no signal from the hepatic artery.

19:59

You've got to get really, really speedy about

20:04

calling people and telling, telling your transplant

20:07

surgeons, "I don't see the hepatic artery."

20:09

And, uh, you know, sometimes these patients

20:11

have bandages and you can't see it because, you

20:13

know, it's just a hard window that can happen.

20:16

Um, but, but if you don't see it, you've got to panic and

20:20

you've got to, you know, call your transplant surgeons

20:22

and then they have to decide whether they're going to

20:24

take the patient back to the operating room,

20:27

or if they want to get an angiogram done.

20:29

Now, an ultrasound, uh, doesn't diagnose this condition.

20:33

Um, it, it creates a very high suspicion for this

20:37

condition, and this is how it looks on a CTA.

20:39

You see a stump of a hepatic artery, and nothing distally.

20:43

So those two arrowheads show

20:44

the stump of the hepatic artery.

20:46

And this is hepatic artery thrombosis.

20:48

There's no vasculature internally.

20:50

So, uh, you suspect it on ultrasound, you

20:54

confirm it on any sort of an angiogram,

20:56

whether it be CTA, catheter angiogram.

20:59

And on occasions, the surgeons will take the

21:00

patient back to the operating room because their

21:02

suspicion is so high and they don't want to wait.

21:05

Now, the reason this is such an important diagnosis to make

21:08

is that because if you don't make this diagnosis

21:11

or make a delayed diagnosis, it can lead to, um,

21:14

uh, infarction of the, uh, of the transplant.

21:17

Now, in a native liver, we all know from our, uh, study

21:21

of anatomy that, you know, in a native liver, most of

21:25

the blood supply to the liver is from the portal vein.

21:29

Uh, 80 percent or so is from the portal vein.

21:31

A very small percentage is from the hepatic artery.

21:34

In a transplant liver, it's the reverse.

21:37

Um, the only source of blood supply to the bile

21:40

ducts in a transplant liver is from a hepatic artery.

21:43

So, if the hepatic artery is thrombosed, you get biliary

21:47

ischemia and infarction, and the transplant is dead.

21:50

Um, so that's why this is really, really important, right?

21:54

So, sometimes you can get false positives, and

21:56

sometimes you can get false negatives, but this

21:58

is not a condition that you would take lightly.

22:01

Um, it's okay to do, uh, an angiogram and

22:04

then make sure that, okay, you see the artery.

22:06

I didn't see it on option.

22:07

That's, that's cool.

22:08

That's fine.

22:09

Uh, but you can't, but you can't sit on it.

22:11

This is a case where, uh, a hepatic

22:14

artery thrombosis was treated.

22:16

So, again, you see a stump of a hepatic artery; they

22:19

were able to, uh, lyse the thrombus and open it.

22:22

Um, if they are unable to open it, um, there

22:25

may be another transplant that may be needed.

22:28

This is a pediatric, uh, liver transplant.

22:32

Uh, the thing that's striking here is that there's a T-tube.

22:35

This was left in there so they could inject

22:37

the bile ducts because they had, um, very high

22:40

concern for problems happening in the bile ducts.

22:43

And you can see what's going on in the bile ducts.

22:45

Those are wispy, irregular bile ducts throughout.

22:48

And this is, um, basically ischemia in the bile ducts.

22:52

I'll show you the, the CT scan.

22:54

This is the CT scan.

22:55

So, there's all these peripheral, uh, liver infarcts.

22:59

Uh, there's not much, uh, these are the infarcts

23:02

and, uh, this is more centrally the infarct

23:05

and, uh, there's a very, very tiny stump

23:09

of the hepatic artery that's seen on the image on the right.

23:13

So, you don't want this to happen.

23:15

You want to pick, you want to pick up this occlusion of

23:18

the hepatic artery before this sets in, because once

23:22

this sets in, this kid is just waiting for a new liver.

23:26

So, what else can happen that can look pretty confusing?

23:31

So, uh, the infarcts may or may not get super infected.

23:37

Uh, they may or may not have gas in them.

23:40

Gas doesn't always mean super infection.

23:43

Um, so you may have to, like, biopsy that something

23:45

like this to figure out if this is just air from

23:48

the infarct or this is really an infected area.

23:52

Um, this is a condition that's actually not very

23:57

well recognized by radiologists for some reason.

24:00

And these are biliary casts.

24:02

Um, uh, I have to admit, I don't diagnose a

24:05

lot of biliary casts, but, you know, they're

24:08

pretty dramatic when you actually see them.

24:10

There are these echogenic things

24:12

that are within the bile ducts.

24:14

And this is how they look on MR.

24:17

So these are biliary casts; this is an ERCP image.

24:24

Okay, now we talked about fish-mouth

24:26

anastomosis; let's talk about pseudoaneurysm.

24:28

So the fish-mouth anastomosis looks like a fish mouth.

24:32

This thing looks like a blob, it

24:35

looks like a circle, a sphere.

24:38

And then you have this ultrasound artifact,

24:41

the yin-yang phenomenon or yin-yang artifact.

24:45

It's basically the to-and-fro waveform.

24:48

Um, the thing to know about pseudoaneurysms is

24:50

that, um, when it hasn't ruptured, um, there,

24:54

there are no clinical symptoms.

24:57

But when it does rupture, there's

24:59

a huge bleed, and it, you know, it can

25:02

be fatal in a high percentage of patients.

25:04

So, um, you have to always look for pseudoaneurysms

25:08

in a post-transplant setting.

25:11

Um, everybody, for the most part, is now transitioning

25:16

to dictations that are very templated.

25:18

So this should be one of your templates, where you

25:21

have to look at, you know, pseudoaneurysms.

25:24

Present or absent.

25:26

This is another example of pseudoaneurysm.

25:28

They don't have to be at the porta hepatis;

25:31

they can actually even be intraparenchymal.

25:33

A lot of these livers get lots of biopsies

25:36

periodically to look for rejection.

25:43

Moving on to the portal vein.

25:44

So, um, everybody knows this, right?

25:46

So, um, hepatopetal flow,

25:48

monophasic, um, normal portal vein.

25:51

Uh, you can get hepatofugal flow

25:55

when there's portal hypertension.

25:57

Now, portal vein stenosis is a complication.

26:03

It happens, um, but it's not an acute complication.

26:07

Um, how do you diagnose a portal vein stenosis?

26:11

Well, at the anastomosis, you get three

26:14

to four times increased velocity, as the

26:17

native velocities will be really high.

26:20

Why do you get this?

26:21

Mostly because of a caliber mismatch during surgery.

26:26

So, how can it be treated?

26:29

Well, balloon angioplasty for the most part.

26:33

Portal vein thrombosis—uh, nothing special about

26:37

portal vein thrombosis other than that it has to be treated.

26:40

Chronic portal vein thrombosis with cavernoma

26:43

formation, um, doesn't need any specific treatment.

26:48

Arteriovenous fistula, how do you

26:50

diagnose an arteriovenous fistula?

26:52

Well, if you've actually spent time in the ultrasound room,

26:55

you can actually diagnose an arteriovenous fistula just from

26:59

what it sounds like on Doppler—that machinery sort of sound.

27:03

Even if you're not in the room, you're outside; you’re

27:06

outside the ultrasound room, you can actually just

27:09

listen to it and diagnose arteriovenous fistula.

27:13

But that’s how it looks on

27:14

ultrasound, and on a CTA or MRA,

27:18

if you start to see a lot of veins

27:20

in the early arterial phase, there’s

27:22

got to be an arteriovenous fistula.

27:26

Hepatic veins—you get, um, so you have a

27:30

normal phasic flow in the hepatic vein that represents

27:34

pressure changes in the right side of the heart.

27:38

And, uh, what happens when you get stenosis?

27:40

Well, same thing as the portal vein—you get really, really

27:43

high velocities, aliasing at the site of stenosis.

27:48

There may be blunting of waveforms, but you definitely want to

27:51

show that; you want to move the patient into

27:54

the decubitus view to make sure that persists.

28:01

Hepatic vein stenosis quite commonly

28:04

happens—remember, every complication

28:06

happens at the surgical anastomosis.

28:08

So you're, you're going to have a stenosis at the

28:11

piggyback anastomosis, and then you, you can angioplasty it.

28:15

Um, when, when is it a significant stenosis?

28:20

On the venous side, a pressure gradient of

28:22

five millimeters of mercury, um, is considered

28:25

a significant, um, hemodynamically

28:29

significant pressure gradient on the venous side.

28:31

On the arterial side, the number is 20.

28:34

Um, so you, you need, you can do an angioplasty;

28:37

instead, you can get, uh, hepatic vein thrombosis.

28:41

Biliary complications, um, are common.

28:44

Um, they're, they're not usually

28:47

very acute or very significant.

28:49

Um, what happens is that, um, you

28:52

can get two types of biliary issues.

28:54

One is the anastomotic stricture.

28:56

How do you identify an anastomotic stricture?

28:58

Well, it's very focal only at the site of anastomosis.

29:02

Um, and, and the rest of the bile ducts look totally fine.

29:06

So this is, they may be dilated from the stricture,

29:08

but other than that, they look totally fine.

29:10

Uh, if, if the bile ducts look very, very ugly,

29:15

you're probably looking at an ischemic stricture.

29:19

So ischemic cholangiopathy looks like that;

29:21

anastomotic stricture looks like that.

29:23

These are the only two, like, biliary images that

29:26

you need to burn in your mind, um, for this topic.

29:30

Now, bile leaks, uh, small bile leaks, very,

29:33

very common, um, and what do we do about them?

29:37

If, if they're small and they continue to

29:39

remain small or decrease, not really much.

29:42

Um, you can, you can diagnose and treat

29:45

at the same time if you're doing an ERCP.

29:48

Um, but if they're large, uh, biliary

29:50

leaks, they may have to be treated.

29:53

Cholangitis, uh, this fluffy,

29:55

feathery, uh, signal with enhancement.

29:59

Um, is, is, is, uh, pretty classic for

30:02

cholangitis in this setting, especially higher

30:04

risk if there is a choledochojejunostomy.

30:07

Um, peritransplant fluid collections, uh, the most important

30:11

thing is to put a color box on any, any transplant or

30:15

peritransplant fluid collection because you absolutely

30:19

want to make sure that it's not a pseudoaneurysm.

30:21

Now you don't want to be putting a

30:22

drain in a pseudoaneurysm, right?

30:24

So any, anytime you see a peritransplant fluid

30:27

collection, do not put a needle into it until

30:31

you've made sure there's no color flow through it.

30:34

And these are your options, pseudoaneurysm.

30:39

Um, if they're small, they're decreasing,

30:42

you don't need to do anything.

30:44

Uh, if they're large, make sure it's not

30:46

a pseudoaneurysm, then you can drain it.

30:48

Um, they can look, um, different.

30:52

They can have septations.

30:53

They can have a hematocrit fluid level.

30:55

Um, they can look pretty ugly.

30:57

So, um, peritransplant fluid collection, um, again,

31:01

the most important thing, um, before you try to

31:04

manage it is to make sure it's not a pseudohemorrhage.

31:07

Now malignancy.

31:09

So, there's only one thing you need

31:11

to know, uh, about, uh, malignancy.

31:14

Any mass in the setting of any transplant.

31:17

And, and it's a very simple, uh,

31:20

uh, you know, educational principle.

31:24

If, if a patient has had a transplant and

31:28

there is something that looks like a mass, the,

31:30

the next step is going to be a biopsy, right?

31:34

Now this is true like 99 percent of the time.

31:37

The only exception being if the malignancy

31:40

that you're looking at is very classic.

31:41

So if you have an HCC that's showing the

31:44

classic wave, uh, classic enhancement pattern

31:47

of an HCC, maybe you don't have to hedge there.

31:50

Um, but what happens here is that it is a long

31:53

laundry list of the differential diagnosis.

31:55

The differential diagnosis includes, you know, the tumor

31:58

that for which the transplant was done may have come back.

32:01

But you can have a whole host of other malignancies, either

32:05

de novo from cancer health happening elsewhere in the body,

32:09

or cancers, some cancers that happen from immunosuppression.

32:13

And in addition to that, you have PTLD, which is post

32:16

transplantation lymphoproliferative disease, which can

32:19

look like anything, which can happen anywhere, any organ.

32:22

I've seen it in the brain too.

32:23

So, um, you have this laundry list

32:26

of, uh, differential diagnosis.

32:28

Don't get too confused by it.

32:30

You see a focal mass in the setting of

32:32

any transplant, be it liver or elsewhere.

32:34

Your next step almost always is biopsy.

32:38

So, uh, it can look like this in the liver, it can

32:41

look like bowel masses, um, it, it can be anything.

32:45

So, again, the most important thing,

32:47

uh, about PTLD is the next step.

32:49

Here's another example of PTLD.

32:52

It can be anywhere, it can look like anything.

32:55

Next step is biopsy.

32:56

So the last thing that I want to talk about

32:58

in the bowel setting is internal hernias, right?

33:02

So with all this surgery, liver transplant

33:06

surgeries, some holes form in the mesentery and

33:10

you have to look for these internal hernias.

33:13

Now internal hernias for an abdominal

33:15

radiologist, tough, tough diagnosis, right?

33:18

But if you look for, um, swirling, if you look for,

33:22

you know, veins, uh, getting pinched and then widening, if you

33:25

look for, um, you know, loops that are forming a cluster,

33:30

if you look for, uh, that cluster having a little neck,

33:33

um, if you, if you only see dilation in, in, in one part.

33:38

So once you, you know, once the alarm goes off that this

33:41

looks like an internal hernia, you know, almost everyone

33:44

opens a paper to see what type of internal hernia this is.

33:48

And, and giving the name and giving a fancy name and getting

33:52

the type of internal hernia absolutely right is amazing.

33:56

But I think more important is, uh, just picking out that

33:59

there might be an internal hernia here and tipping the

34:01

surgeon so that the patient can go to the operating room.

34:05

So, um, this is an internal hernia

34:08

with this hole in the mesentery.

34:10

So, um, now this is the most important slide.

34:13

So this is where you need to pay attention.

34:14

So we were building up to this slide.

34:16

Uh, we have a copy of the slide that's pasted

34:19

in our ultrasound reading room.

34:21

Um, it took a lot of effort for

34:24

us to, you know, organize this.

34:25

I sent a lot of emails to our transplant surgeons

34:28

to get, to get this algorithm just right.

34:30

So the most important thing in a transplant setting

34:33

is whether you have symptoms or you don't have symptoms.

34:35

The first step can always be an ultrasound.

34:37

So it's a screening test.

34:39

It can show a lot of things.

34:40

It can show a completely normal ultrasound,

34:43

but remember you can have symptoms.

34:45

You can have abnormal LFTs, but what if

34:47

you ended up with a normal ultrasound?

34:49

Well, the next step is biopsy because the number one

34:51

thing you want to exclude is rejection, and you can

34:54

have other things like drug toxicity, uh, that may

34:57

be producing those symptoms or abnormal LFTs.

35:01

Now, if on that screening ultrasound, you

35:03

see biliary dilation, um, the next

35:07

step should be if, do you want to treat that

35:10

biliary dilation in which you would do ERCP?

35:12

Because in ERCP you can diagnose and treat at the same time.

35:16

Or if you, or if it's not urgent, you can do

35:18

MRCP for planning and then proceed with the ERCP.

35:21

If the ultrasound shows a transplant or

35:23

peri-transplant fluid collection, remember?

35:26

Always exclude a pseudoaneurysm first.

35:29

Once you've done that, you can decide how to treat it.

35:32

If it's, if it's a small fluid collection,

35:34

you can continue to observe it.

35:36

If it's a large one causing mass effect,

35:39

um, then you may want to treat it.

35:42

If you have a portal vein thrombosis, if it's a

35:44

new thrombosis, obviously you want to deal with it.

35:46

If it's an old thrombosis and it's collateralized,

35:50

there's nothing you need to do about it.

35:52

Um, hepatic artery thrombosis.

35:56

Remember, this is the "do not miss" case

35:59

because the ramifications are huge.

36:01

If you miss a hepatic artery thrombosis,

36:03

you're going to kill the transplant.

36:04

So don't miss that.

36:07

In an acute setting, you want to re-explore,

36:10

you want to, you know, I showed you all

36:11

those cases where IR was able to help out.

36:15

But, but in acute hepatic artery thrombosis is the

36:17

most important, um, entity amongst all of this.

36:21

If you have, if you, if, if you do an

36:23

angiogram and you see those collaterals,

36:24

you know, you can have conservative management.

36:27

If you see a mass, the next step is biopsy. Anything, anything else,

36:30

um, is academic, uh, in the, uh, in the transplant plus

36:35

focal mass scenario.

36:38

Uh, a while back we, um, we organized an issue,

36:42

uh, on topics in transplantation imaging for,

36:45

uh, Radiologic Clinics of North America.

36:49

I worked with, um, one of my friends, uh, Dr.Heller.

36:53

He's now at the Mayo Clinic.

36:54

Um, this is, uh, not much has changed, actually.

36:58

Uh, even though this issue was compiled in

36:59

2016, um, the concepts still remain the same.

37:03

Um, uh, most of the images that I showed you and that

37:07

algorithm in case you want it, it's, uh, it's actually a

37:10

part of this paper that I wrote in my fellowship years.

37:12

These are...

37:13

These are some other good papers in

37:15

Radiographics, um, about liver transplant.

37:18

I specifically recommend at least glancing through the

37:22

paper on the right because it actually shows what are the

37:25

reversible findings in the immediate postoperative period.

37:30

With that, let's spend a few minutes on the second topic.

37:35

So, um, the next topic is, um, how to help a

37:40

surgeon when, um, they're trying to do a liver

37:44

resection for a malignant liver lesion, right?

37:46

What can, how can we help?

37:49

So, um, the most important thing here to understand

37:54

is that even though we spend a lot of time talking

37:56

about liver transplant imaging, um, surgical

38:00

resection is the treatment of choice in hepatocellular

38:04

carcinoma and in colorectal cancer metastases.

38:12

So, um, how do we, how do we help the surgeon here, right?

38:17

So, um, why is surgery, surgical resection,

38:22

the treatment of choice and not transplant?

38:25

That is because this actually increases the

38:28

five-year survival rate and when the selection,

38:31

uh, when the selection is done appropriately,

38:34

and it offers the potential for cure, right?

38:37

So, um, liver transplant, we have the Milan

38:40

criteria, which is three tumors less than three

38:43

centimeters or one tumor less than five centimeters.

38:47

Anything outside of this will not fit in the

38:51

transplant setting, but if at all possible,

38:54

surgical resection is the treatment

38:56

of choice for liver transplant.

38:59

Now, why do we do surgical resection?

38:01

Because the goal is to eliminate macroscopic disease.

39:04

So if you can actually resect the liver,

39:07

and that is the only site of disease on the PET

39:11

image that's shown, then you would do great.

39:15

Then that tumor can be resected.

39:18

You want to make sure that the, um, that the

39:20

liver function, uh, is, uh, is appropriate.

39:25

Uh, this is all done, uh, by the, by the surgical team.

39:28

You want to make sure that the disease is localized.

39:30

You want to make sure that there's no extrahepatic disease.

39:35

And this is how we plan.

39:37

So you want to do what's called, uh, CT volumetric, right?

39:41

So, um, in surgical resection for a

39:44

malignant liver lesion, there's no size criteria.

39:47

You can resect a 10-centimeter

39:49

mass if it's exophytic.

39:51

Um, but you may not be able to resect a much

39:54

smaller tumor if it's at the wrong location.

39:56

So there's no size criteria.

39:58

in liver transplant resection.

40:00

But what you want to do is you want to make,

40:01

you want to make, you want to first make sure

40:04

what, what kind of surgery you're planning.

40:06

And you also, uh, want to, you want to have a

40:10

sense of how much liver is going to be left behind.

40:13

So, so what happens is that you, you locate your

40:17

tumor, you figure out what segments you're going

40:19

to take out, what you're going to leave behind.

40:22

And the way it works is that when you leave behind, um,

40:27

normal liver, uh, you actually need quite a bit less of it.

40:31

But if you leave behind a cirrhotic liver, then,

40:35

then you have to leave quite a bit more of it.

40:37

And we'll, we'll talk about that.

40:39

So traditionally, um, if you have multiple lesions,

40:44

um, if, if you can't achieve, uh, adequate resection

40:49

margin, if you have extrahepatic metastases,

40:51

for colorectal mets, uh, that's a contraindication.

40:54

For HCC, once you get portal venous, uh, or

40:58

hepatic venous invasion, uh, invasion of other

41:01

organs other than the gallbladder, disc,

41:03

and metastases, um, now you can't actually do surgery.

41:08

So this is a nice, uh, example to show, you know,

41:11

that these patients are not good candidates.

41:15

So, um, image on the left here, um, enhancing tumor

41:19

going into the heart, um, tumor thrombus going into

41:23

the portal vein, multifocal disease and whatnot.

41:27

So I think, um, everybody who reads livers, um, should

41:31

be very familiar with, um, anatomic liver segments.

41:35

Um, so this is just a recap.

41:37

I'm not going to go into liver segments, but uh, if you

41:39

haven't figured this out, um, it's very important to

41:42

describe these liver lesions and which segments they are,

41:46

and they may occasionally be across multiple segments.

41:50

So I think this, uh, this nomenclature

41:53

is, is really important to understand.

41:55

Um, so, uh, left hepatectomy is segments

42:00

two, three, and four, but left lateral

42:02

lobectomy, uh, segment four is not resected.

42:05

Uh, you'll, you'll often hear about right hepatectomy,

42:09

which is five, six, seven, eight, not four.

42:11

Um, but then if the surgeons want to remove segment

42:14

four, in addition to five, six, seven, eight,

42:16

it's an extended right hepatectomy, right?

42:19

So the others are not that common.

42:22

So, um, what are the indications for major liver resection?

42:26

So like I was talking about, sometimes the

42:28

masses are not isolated to a liver segment.

42:31

They may actually cross multiple segments.

42:34

So when they cross multiple segments, that's

42:37

when you know you have to resect more than four

42:39

segments and that's a much more involved surgery.

42:43

But our job here is to describe what

42:46

segments are crossed by the tumor.

42:48

So you can see even large tumors can undergo resection.

42:53

There's no size criteria.

42:55

Here's some examples of, you know,

42:58

tumors that underwent resection.

42:59

So that 55-year-old man, the large

43:02

right-sided tumor was resected.

43:05

Segment A and B is preoperative.

43:07

Image C and D is postoperative,

43:09

but unfortunately, he had a recurrence.

43:12

The case on the right, um, underwent right hepatectomy.

43:16

Now, this is how it looks in the operating room.

43:19

Um, this is courtesy of one of our,

43:20

uh, surgery colleagues from U Dub.

43:22

Um, so the tumors can be taken out

43:25

and this is how they look post-surgery.

43:28

Uh, our job is to, to identify segments and also

43:32

define for the surgeons in multiphasic images, uh,

43:36

the relationship of the tumor to the different veins.

43:41

So, uh, here's some more

43:43

examples of, uh, tumor resection.

43:46

Um, lots of tumors.

43:47

The more central the tumor becomes, the more

43:50

extensive the liver resection has to be.

43:53

And that's exemplified in the case at the bottom.

43:56

Um, now there are some, there are some resections

44:00

that are atypical resections or wedge resections.

44:03

Um, so sometimes we get lucky.

44:05

Sometimes tumors are at the periphery,

44:07

and they're not central.

44:09

And even though they may be multiple,

44:11

uh, we can actually just wedge them out.

44:14

Wedge them out means we take a triangular piece

44:16

of tissue at the periphery of the liver and we

44:18

don't have to do large liver segment resections.

44:22

So this is how, um, wedge resections look like.

44:25

So sometimes you'll see, um, you know, patients

44:29

who come in with imaging that looks like that.

44:31

You, you go back to see the old scans and you see

44:34

that they haven't really done a major resection.

44:36

They've just done a wedge resection.

44:38

So just taking triangular pieces of tissue at the periphery.

44:42

So, um, the last thing I'm going to

44:45

talk about is portal vein embolization.

44:47

Uh, portal vein embolization, uh, it,

44:50

it's not a common procedure, but you may

44:53

come across, uh, this entity occasionally.

44:57

Um, so what happens is that, um, you want to leave,

45:00

uh, about 15% of normal liver behind and 40%

45:05

of cirrhotic liver behind at the minimum.

45:09

Now your surgeons may use slightly different numbers.

45:11

So please check with them.

45:12

Some surgeons are more conservative.

45:14

They leave slightly more than the numbers that I described.

45:18

But in portal vein resection, a portal venous embolization,

45:22

PVE, um, what happens is that the, the residual liver

45:27

as we're planning, um, is, is actually, um, borderline.

45:33

So they want to grow that liver a little bit.

45:35

So what they do is they embolize the

45:37

portal vein on the side of the tumor.

45:39

And they wait, uh, for this window of four to six weeks.

45:44

They do a repeat, uh, uh, CT volumetric to

45:47

make sure that the liver, the liver has grown.

45:50

And then they do the surgical section.

45:52

So that's portal vein embolization.

45:53

So, remember, um, the treatment of choice for a malignant

45:59

liver tumor is surgical resection, and a transplant is

46:04

the treatment of choice for end-stage liver disease.

46:07

Uh, it's only the second-best option for, uh, for, um,

46:12

uh, for treatment of focal malignant liver lesions.

46:17

So with that, we can take some questions.

46:28

Yes, so one of the questions is, can

46:30

contrast-enhanced ultrasound help to

46:33

detect hepatic artery with more confidence?

46:36

Uh, yes.

46:37

So, um, increasingly, um, contrast-enhanced ultrasound is being utilized,

46:42

um, to outline, um, the hepatic artery.

46:46

To look at, um, enhancement characteristics of focal liver lesions.

46:51

Now, uh, unfortunately, uh, North America is pretty

46:55

behind, um, compared to their European, um,

46:57

uh, ultrasound colleagues,

47:01

because Europe is far more advanced in utilizing,

47:06

um, microbubble contrast agents and ultrasound.

47:10

But yes, uh, increasingly, uh, everybody in North

47:13

America, uh, is utilizing, uh, microbubble agents.

47:16

Um, but again, whether you use microbubble contrast or, or

47:21

CCTA, it really, the decision, and from what I have seen,

47:31

they continue to use, uh, angiogram as the primary modality.

47:35

Uh, not so much.

47:38

Uh, not so much, uh, microbubble ultrasound contrast.

47:43

So the other, uh, the other question

47:45

is, what is the threshold for biliary

47:48

ductal dilatation in a transplant liver?

47:50

So there's no size threshold that we use.

47:53

Um, you can get minimal ductal dilatation, um, in, um,

48:02

in some livers.

48:04

We're not super concerned about minimal ductal

48:06

dilatation, but, uh, if it starts to become,

48:11

um, more than minimal with, um, changes in liver

48:16

function tests, that's when we get concerned.

48:18

So there's no size criteria for biliary ductal dilation.

48:22

Okay, the next question is, is piggyback

48:25

anastomosis done for adults other than kids?

48:28

Piggyback anastomosis, um, is, uh, the

48:34

only, uh, anastomotic, uh, technique that we do

48:38

nowadays, um, in orthotopic liver transplants.

48:42

Uh, I don't know about in the pediatric

48:45

setting since I'm not a pediatric radiologist.

48:48

Um, does NAFLD change the threshold

48:53

for residual liver volume?

48:55

Um, I think the residual liver volume, um, is

49:00

mainly based on whether, uh, it's related to, um,

49:06

the imaging appearance of the residual liver, if,

49:09

and on the biopsy, if the residual liver is, is

49:13

thought to be, um, cirrhotic versus non-cirrhotic.

49:17

So, uh, other than that, I don't know

49:19

much more specific about, uh, NAFLD.

49:23

But transplant surgeons are all on top of this.

49:26

This is a good question to ask them.

49:29

But I think if we, like in the liver transplant,

49:32

I kid you not, if you can look at the hepatic

49:34

artery and make sure that the hepatic artery is

49:38

open, when you're taking Paul, you've done more

49:43

than, more than your job in the emergent setting.

49:47

And if you can actually, uh, that algorithm from the

49:50

AJR article that I wrote many years ago, if you can

49:54

just, uh, you know, get that algorithm and put it

49:57

in your ultrasound room and then just follow that

50:00

algorithm, uh, you'll manage these things exactly right.

50:04

But, uh, if you're new to liver transplant

50:06

imaging, uh, it's definitely worth, um, spending

50:11

a few minutes, uh, looking at the preoperative

50:13

technique when your surgeons come down or call you.

50:16

So definitely ask them questions about what

50:18

surgical techniques they're using and whatnot.

50:21

And, um, um, when you have a confusing case, call them.

50:24

So, so that, uh, you can understand what

50:27

their thinking is and how they're managing it.

50:33

Okay.

50:33

Any more, any more questions?

50:36

I think we've run out of questions.

50:38

Maybe we can give it another minute, uh, just in case any of

50:41

the other attendees want to, um, you know, get anything in.

50:45

Okay.

50:46

I'm happy to take any other liver

50:47

questions, too, if anybody has them.

50:51

There are a couple just, uh, populated.

50:55

Okay.

50:59

So, um, what is the, uh, uh, preferred imaging modality for

51:05

hepatic artery thrombosis, CTA versus catheter angiography?

51:11

Again, this is not a decision that we make.

51:13

This is a decision that the transplant team makes.

51:17

If, um, if in the operating room, um, the,

51:21

the, the caliber, uh, of the hepatic artery,

51:24

the donor recipient mismatch was significant.

51:28

And they're actually expecting hepatic artery complications.

51:33

They may take the patient back to the

51:34

operating room or go for a catheter angiography

51:37

because at the same time they can treat it.

51:39

But if, but if they're not that the

51:41

patient is doing really, really well.

51:43

If the, if the liver function tests are great.

51:46

Uh, then, uh, they may be like, well, let's do a CT and

51:49

just make sure because our index of suspicion is really low.

51:53

Um, Do we use Lyrads for liver transplant mass?

51:58

Um, not really.

51:59

So the reason we don't is because in the,

52:02

in the post transplant setting, Um, Uh,

52:07

HCC is not the only tumor that happens.

52:10

And so, um, you know, bottom line, if you get a

52:14

focal mass, that's new in the post, uh, transplant

52:18

setting, whether it be liver transplant or any

52:20

other transplant, the next step is always a biopsy.

52:27

All right.

52:28

Well, I think that is it for the questions.

52:30

And as we bring this noon conference to

52:32

a close, I would like to thank, uh,

52:35

Dr. Bhargava for this lecture and thanks to all of

52:37

you for participating in our noon conference.

52:40

A reminder that this conference will

52:41

be available on demand on MRI online.com

52:45

In addition to all previous noon conferences and be

52:48

sure to join us again on Friday for a lecture from

52:51

Dr. Megan Mills on traumatic injuries of the brachial plexus.

52:55

You can register for that at MRI online.

52:59

com and follow us on social media at the MRI online

53:03

for updates and reminders on upcoming noon conferences.

53:06

Thanks again and have a great day.

53:08

Thank you.