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Hello and welcome to Noon conferences hosted by MRI online.

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3 00:00:06,270 --> 00:00:08,340 In response to the changes happening around the

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world 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. Udare. Dr. Udare completed

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his diagnostic radiology residency from

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Tata Hospital in India and abdominal imaging

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fellowship at the University of Ottawa.

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He’s currently a cross-section imaging

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fellow at McMaster University, Canada.

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His areas of interest are body

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imaging and radiology education.

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A reminder that there will be a Q and A session

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at the end of the lecture, so please use the

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Q and A feature to ask your questions, and we will

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

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We will also be using our polling feature

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today, so be on the lookout for that.

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A reminder that the polling window can be moved

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on your screen if it is blocking something.

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That being said, thank you all

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for joining us today. Dr. Udare,

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I'll let you take it from here.

1:09

Thank you, Ryan, for the kind introduction.

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Uh, I'd like to thank Dr. Collins and the entire

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MRI Online team for giving me this opportunity.

1:18

Uh, in the next, uh, one hour or so, we'll

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discuss CT and MR imaging of the adrenal glands.

1:24

Um, as Ryan mentioned, this is

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gonna be an interactive session.

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Uh, so keep a lookout for the polls and try to

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participate as much as possible because that will help

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with, uh, uh, retention of concepts that we discussed.

1:39

So let's start.

1:45

So I have no, uh, relevant disclosures.

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We will begin our, uh, presentation with a few cases.

1:52

So, uh, if you can have a look at this case.

1:56

And the question here is, what is your

1:58

diagnosis for this left adrenal nodule?

2:01

In case it's difficult to visualize this

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on the smaller screens, I'll point it out.

2:06

Uh, on the image.

2:10

We'll give around 30 seconds, so for

2:13

everybody to vote in their answers.

2:15

The average attenuation in this case was plus five

2:19

Hounsfield units, and this is a non-contrast CT.

2:24

So we can have the answers.

2:26

Uh, so move on to the next question.

2:33

Okay, so 59% of you said adenoma, which is correct.

2:37

Let's move on to the next question.

2:40

The question remains the same.

2:42

What is your diagnosis for this left adrenal nodule?

2:49

So some of it might be, uh, basic for a few

2:53

of you, but what I've tried to do is I've,

2:55

I've structured the talk in such a way that we

2:57

will cover the basic concepts and we'll touch

2:59

over the advanced concepts in the later part

3:02

of the talk so that everybody finds it useful.

3:08

Good morning, good evening, good afternoon.

3:09

Depending on what part of the world

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you're attending this conference from.

3:15

Okay, so around 59% of you got this one right?

3:19

Uh, so this was not an adenoma. Uh, for those

3:21

who couldn't identify, uh, uh, the anomalies,

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I was talking, I was talking

3:26

about this left adrenal nodule.

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Let's move on to the next quiz question.

3:31

Hi.

3:31

And one thing I just wanted to, uh,

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reiterate is if the, um, poll window is

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obstructing your view, you are able to move

3:40

it around your screen so it's unobstructed.

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Just wanted to share that once again.

3:45

Thank you.

3:48

So this is the last of our polling ques—

3:50

uh, polling questions, uh, before we

3:52

start talking about the adrenal glands.

3:56

So the question remains the same.

3:57

What is your diagnosis for this right adrenal nodule?

4:03

The attenuation in this case was

4:05

around plus 18 Hounsfield units.

4:09

Okay, so for this one, uh, we've got a mixed

4:12

response, and we'll discuss, uh, each of these

4:15

cases during our talk—so, of horses and zebras.

4:19

So for those who have, uh, most of us during medical

4:22

school have heard this term called “zebra syndrome.”

4:25

So this, uh, is something which comes from

4:27

Maryland. Dr. Theodore Woodward, uh, uh,

4:30

famously said that when you hear hoofbeats

4:33

behind you, you don't expect to see a zebra.

4:36

The thought process behind that was Maryland

4:38

is famous for its horses and horse races.

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Uh, so if you hear hoofbeats,

4:43

it's more likely to be a horse than a zebra.

4:46

Uh, the reason that I put this up is, uh,

4:49

in any pathology in medicine in general, we need to

4:52

focus on the common abnormalities first, and then

4:55

we can always think about the rare differentials.

4:58

So that's what we are gonna do today.

4:59

Uh, we are gonna talk about the common anomalies, and

5:02

if time permits, we will go over the adrenal zebras.

5:05

So what are our adrenal horses?

5:07

The most common adrenal lesions, they

5:10

include adrenal, adrenal cortical adenoma.

5:12

And if you see number one and number two, both

5:14

are adenomas because that's the most common

5:17

incidental benign, uh, adrenal nodule that is seen.

5:21

The other, uh, common anomalies are

5:22

hemorrhage, mets, and myelolipomas.

5:25

And rarely you get to see pheochromocytomas

5:27

and adrenocortical carcinomas.

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The objectives of today's talk are I will review

5:33

the CT and MR anatomy of the adrenal glands, a common—

5:37

I'll review a few common adrenal pathologies, a

5:41

quick, uh, overview of MRI as a problem-solving tool.

5:44

Uh, we'll discuss approach to incidental,

5:47

uh, adrenal incidentalomas, and if time

5:50

permits, we'll review a few zebras and try

5:52

to answer a few questions from the audience.

5:56

So there are multiple ways to

5:57

classify adrenal anomalies.

6:00

You can classify them, uh, on the basis of if

6:02

they're benign, if they're malignant, uh, are

6:05

they arising from the cortex or the medulla, or

6:08

they're functioning versus non-functioning.

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All of that is not really, uh, uh, uh,

6:13

very, uh, handy while you're reporting.

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So what I've decided is, uh, the talk is structured,

6:19

uh, on the basis of what we commonly see.

6:23

So most commonly we see adrenal nodules

6:26

on CT, and then we need to decide

6:28

what needs to be done, uh, after that.

6:30

So that's how I've divided the talk.

6:33

We'll talk about focal abnormalities,

6:35

which are either fat or fluid density.

6:37

So anything less than 10 HU. Then

6:39

what are soft tissue attenuation

6:41

lesions that are more than 10 HU?

6:44

And then we'll talk about a few hyperdense

6:46

lesions, a couple of diffuse anomalies.

6:49

Uh, I'll not be talking about pediatric

6:51

pathologies such as neuroblastoma in this talk.

6:56

Coming to imaging anatomy.

6:57

So adrenal glands are bilateral, Y- or

7:02

inverted Y- or inverted V-shaped structures.

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Uh, each one has a body and medial and lateral

7:08

limbs. For those who are interested in numbers,

7:11

uh, typically the body is around six

7:13

to eight millimeters thick, and the

7:14

limbs are around three millimeters.

7:16

The right adrenal gland is suprarenal,

7:19

while the left adrenal gland is more of adrenal—

7:23

it's better appreciated in the axial sections.

7:26

The arterial supply is by three arteries,

7:29

and they drain into single veins.

7:31

On the right side,

7:32

they drain into the IVC, while on the left

7:34

side they drain into the left renal vein.

7:38

This has important, uh, clinical, uh, application,

7:41

and we'll discuss that later in our talk.

7:45

So the adrenal gland shape is, uh, determined

7:49

by the presence or absence of renal tissue.

7:52

So in cases where the kidneys are not

7:54

present in their, in the renal

7:57

fossa, uh, the adrenal shape is abnormal.

8:00

So, uh, if you see this case, this is in

8:02

T2-weighted MR image. The shape of the

8:05

adrenal gland is flattened as, uh, opposed

8:08

to the normal inverted V- or inverted Y-shape.

8:13

Uh, and this patient had an ectopic pelvic kidney, so

8:16

this is what is known as the lying down adrenal sign.

8:19

Uh, this can be useful in certain cases where

8:22

if you're having a tough time determining if

8:24

the kidney is absent or has been operated on.

8:28

In patients with congenitally absent

8:30

kidneys, the adrenal glands will have this

8:33

flat or lying down kind of appearance.

8:35

While in cases of patients with

8:37

nephrectomy, the adrenal glands will

8:39

have their normal, uh, reniform shape.

8:42

So this lying down appearance of adrenal gland

8:44

can be seen in any renal anomaly where the

8:47

kidneys are not present in the normal renal fossa.

8:51

So that includes, say, an ectopic

8:52

kidney, an absent kidney, a horseshoe

8:55

kidney, or a crossed fused ectopic kidney.

9:00

So this sign has been also described as the pancake

9:03

adrenal glands because of their flattened shape.

9:06

Uh.

9:07

This is an adult patient, but this sign

9:10

is also seen on, uh, antenatal ultrasounds.

9:13

For those who do fetal imaging, uh, make sure that,

9:16

uh, if you see the sign you should look for, uh,

9:20

uh, and the kidneys are absent, uh, that suggests,

9:23

uh, uh, renal ectopia or absent kidneys.

9:26

For those who are not aware or those who are not

9:28

from North America, this is how a pancake looks.

9:31

Uh, you can try to correlate it to whatever

9:33

colloquial term, uh, uh, you can think of.

9:36

So that was the lying down, or pancake.

9:39

Adrenal glands. In cases of, uh, when the kidneys

9:42

are not present in the normal renal fossa, so

9:46

the adrenal gland physiology is quite complex.

9:49

There are, there's a cortex, there's medulla.

9:51

Each of these secretes different hormones.

9:54

Even the embryology is quite complex.

9:56

Luckily for us radiologists,

9:59

uh, the imaging is not as complex as the physiology,

10:03

so, uh, I'll not go into the details of this.

10:05

If you're interested, you can just

10:06

take a screenshot, uh, of this slide.

10:10

Okay.

10:11

Let's begin with fat or fluid attenuation lesions.

10:14

These are the most common lesions, and these

10:17

are touch-me-not lesions, like most of the time.

10:20

Uh, you don't need to do anything about these.

10:24

The first lesion that we are gonna

10:25

talk about is the adrenal adenoma.

10:28

It's a benign tumor of the adrenal cortex.

10:30

It can be functioning and

10:31

non-functioning or non-functioning.

10:34

It's very difficult to determine on imaging if an

10:36

adrenal lesion is functioning or non-functioning.

10:40

A fairly specific but not-so-sensitive sign

10:43

described is that if there's atrophy of the rest

10:46

of the gland or the contralateral adrenal gland,

10:49

that suggests that that could be a functional

10:52

adrenal lesion, be it an adenoma or other tumor.

10:56

The typical imaging features: commonly,

10:58

these are less than four centimeters.

11:00

They have homogeneous attenuation

11:02

and they're well-circumscribed.

11:04

The important number to remember here is

11:07

10 HU, uh, and this has been described as a

11:11

fairly specific sign for adrenal adenomas.

11:15

So if you see a lesion which is small,

11:17

homogeneous, less than 10 HU on a

11:20

non-contrast CT, uh, you can, uh, call it

11:24

an adrenal adenoma with fair confidence.

11:28

Let's have another poll here.

11:32

So let's bring up question number four.

11:36

The question here is, which of these

11:37

possibly could be an adrenal adenoma?

11:45

So this is A. You see this small lesion.

11:48

We've put a small ROI there. This

11:51

is number B, and this is number C.

11:57

There are a few common, uh, there's,

11:59

there are a few common confusions

12:01

in adrenal gland imaging, and that's

12:03

the reason why I'm going over all of these.

12:06

So that, uh, these basic concepts are cleared.

12:09

So most of you have answered it, uh, as B,

12:12

uh, which is right, but I'll explain to you

12:14

why even A and C could be adrenal adenomas.

12:18

So if you see in, uh, the first

12:20

image here, the ROI is too small.

12:23

So whenever you're measuring, uh, an adrenal

12:25

adenoma, or for that matter, any other lesion,

12:28

first of all, you should not use a single pixel.

12:31

Uh, second of all, your ROI should

12:33

cover at least two-thirds of the lesion.

12:36

So, for example, this is a lesion—you should at least

12:39

try to cover two-thirds of the lesion on your ROI.

12:42

So this ROI is too small and

12:44

may not be representative.

12:47

Here the attenuation is plus 18.

12:49

So that doesn't classify, uh, uh, according

12:52

to whatever we discussed earlier, but

12:53

remember that this is a contrast study.

12:56

It could still be an adenoma because,

12:58

uh, the 10 HU, uh, uh, measurement is

13:01

strictly for non-contrast studies.

13:04

So B is absolutely right, but in

13:07

fact, all of these could be adenomas.

13:11

So, as I mentioned, we have to

13:12

measure these on non-contrast CT.

13:14

If it is less than 10 HU on a contrast CT,

13:17

that's fine, but if it's more than 10 HU

13:20

on a contrast CT, then, uh, uh, you, you,

13:23

we can't say if it's an adenoma for sure.

13:25

We have to exclude the periphery because if you see

13:27

there's retroperitoneal fat, which will lower down the

13:30

attenuation value, so you don't want that happening.

13:33

ROI should cover two-thirds of the nodule.

13:36

And small areas of heterogeneity—say, necrosis or

13:39

calcification—may not be truly representative of the

13:42

lesion, and those need to be, uh, uh, excluded out.

13:47

The other fairly common benign hypodense

13:50

lesion is an adrenal myelolipoma.

13:53

This is not to be confused

13:54

with a renal angiomyolipoma.

13:57

This is an adrenal myelolipoma.

13:59

And if you look at the word itself—so lipoma is fat.

14:03

So this lesion has macroscopic fat, and the term

14:06

myelo is usually reserved for hematopoietic tissues.

14:10

So this is a benign adrenal neoplasm, uh,

14:13

consisting of fat and hematopoietic soft tissue.

14:16

So if you see this fat-containing macroscopic,

14:18

uh, lesion containing macroscopic fat in the left

14:21

adrenal gland, this was an adrenal myelolipoma.

14:25

Usually patients are asymptomatic, but

14:27

if the lesion is large, say more than 10

14:29

centimeters, they can cause pressure effect.

14:31

And when they're more than 14 centimeters, typically

14:34

they're, uh, uh, known to cause adrenal hemorrhage.

14:37

Uh, so—

14:40

If you see anything with macroscopic fat, uh,

14:43

be it a contrast or a non-contrast CT, in most

14:46

cases, that would be an adrenal myelolipoma,

14:49

especially if the lesion contains more than 50% fat.

14:53

The management of these is usually observation, and

14:55

the surgical excision is, uh, recommended if the

14:58

lesion exceeds more than seven centimeters in size.

15:02

Important differentials for myelolipomas are

15:05

retroperitoneal sarcomas, liposarcomas, but

15:07

they'll be, uh, they tend to be more ill-defined.

15:11

Uh, and in those cases you may see the

15:13

adrenal glands separately from the lesion.

15:16

The other important differential

15:18

is an exorenal angiomyolipoma.

15:21

But, uh, if you see the adrenal glands separate

15:24

from the lesion and if there's a claw sign

15:27

with the, uh, kidneys, that suggests that

15:29

this is a renal lesion rather than an angio—

15:32

myelolipoma. Uh, and angiomyolipomas tend

15:35

to be slightly more complex than adrenal

15:37

myelolipomas. A couple of companion cases.

15:41

So myelolipomas are also known to

15:43

occur in extra-adrenal locations.

15:46

The most common locations are the presacral,

15:48

retroperitoneum, pelvis, and rarely in the mediastinum.

15:51

So, for example, if you see this fat-containing

15:54

paravertebral mass, uh, in this patient, which

15:56

was incidentally found, this was biopsied and it

15:59

was found to be, uh, an extra-adrenal myelolipoma.

16:03

Similar, uh, uh, story was for this case—a

16:06

presacral lesion, uh, with fat and some soft tissue.

16:10

This was an extra-adrenal myelolipoma.

16:13

An important differential in this case would

16:15

be, uh, extramedullary hematopoiesis, but an

16:18

extra-adrenal myelolipoma will not be usually

16:21

associated with, uh, any hemoglobinopathies.

16:24

And extramedullary hematopoiesis usually

16:27

is bilateral, diffuse, and we'll see multiple

16:29

areas. But again, uh, that's a differential

16:32

you cannot 100% rule out.

16:35

Adrenal cysts are very rare.

16:37

Uh, they tend to be unilateral.

16:39

Uh, these are the causes for those.

16:42

Uh, an important thing to remember is

16:44

that even adrenal adenomas have a similar

16:46

attenuation, uh, as that of a cyst.

16:49

Uh, so it's difficult to distinguish

16:51

just on a non-contrast CT.

16:53

If you have contrast CT, an adenoma

16:55

will show some enhancement, whereas

16:57

a cyst will not show any enhancement.

17:00

In case, uh, there are issues with diagnosing

17:03

these on CT, MRI would definitely, uh, be

17:06

helpful with better soft tissue characterization.

17:10

That finishes our, uh, low-density or fat-

17:13

density lesions. And remember that those

17:15

are the most commonly encountered lesions.

17:18

And now we'll talk about the less common lesions.

17:22

The first lesion that we are gonna discuss is, uh,

17:25

atypical or lipid-poor adenomas, as they are called.

17:29

One-third of patients, they don't have the—these

17:32

adenomas do not have enough cytoplasmic, intra-

17:34

cytoplasmic fat, so that makes the Hounsfield

17:37

units higher than 10 HU for these, uh, adenomas.

17:41

So it's difficult to distinguish

17:42

them just on non-contrast CT.

17:46

So in these patients, it's recommended to

17:48

do what is known as an adrenal protocol CT.

17:51

Uh, ideally we'll do a non-contrast CT and the

17:54

review of the scan because the most commonly

17:57

encountered adrenal nodules are on post-contrast

18:00

images because a lot of the centers, especially in

18:03

North America, we do only a single-phase, single, uh—

18:07

single, uh, portovenous sequence in most cases.

18:09

So that's how we discover adrenal nodules.

18:12

So if you do that, then recommend first a

18:14

non-contrast CT, and if there's a radiologist

18:17

on-site to have a look at it, uh, and the Houns-

18:20

field value is less than 10 HU, nothing needs

18:22

to be done further, but if it is more than 10—

18:25

10 HU, uh, we need to do a venous

18:27

phase—that's at 70 seconds—and the

18:30

delayed phase—that is at 15 minutes.

18:32

It's important to remember these values

18:34

because the absolute and relative washouts

18:37

have been calculated at these, uh, intervals.

18:41

And any interval less than 15 minutes on the

18:44

delayed phase has been found to be not so ideal

18:46

for, uh, evaluating adrenals on a dynamic CT.

18:51

So make sure that your protocol is not a 10-minute

18:54

phase, uh, but it's a 15-minute delayed phase.

18:58

An alternative is chemical shift imaging MRI,

19:00

and I'll discuss that later in the lecture.

19:04

So if you can see this image from Radiology Assistant,

19:06

uh, there's this 24 HU right adrenal nodule.

19:10

It goes up to 88 HUs on the portal venous phase,

19:14

and on the delayed phase it's around 49 HU.

19:18

So the absolute washout is 62, and

19:20

the relative washout is around 40–44.

19:23

So anything, uh, the absolute washout—whenever it's

19:26

more than 60—or the relative washout—whenever it's more

19:29

than 40—that is suggestive of an adrenal adenoma.

19:33

So adrenal adenomas, be they

19:35

uh, uh, even the lipid-poor

19:36

and the lipid-rich ones, they tend to enhance

19:40

early and then they tend to wash out early,

19:43

as compared to, say, metastasis or other

19:45

adrenal lesions, which are slow to wash out.

19:47

So in those cases, the absolute

19:49

and relative washout will be less.

19:52

So, uh, if you go into the formulas for these,

19:55

they can get a bit complex, and this is me

19:57

while trying to figure out the formula for that.

20:00

But you can, uh, use multiple adrenal

20:03

calculators, which are available online.

20:06

I have, uh, linked, uh, one of them here.

20:09

Uh, the important thing to remember is the concept.

20:12

So—

20:13

What are we looking, uh, when

20:15

we calculate absolute washout?

20:17

So we are looking at how much an adrenal lesion

20:20

washes out on the delayed phase compared

20:22

to the original enhancement of the lesion.

20:25

So if you have a non-contrast study, you can

20:28

see the absolute enhancement to begin with.

20:30

And if you don't have a non-contrast study, you

20:33

can use the attenuation on the venous phase.

20:36

As I discussed earlier, absolute, uh, uh, absolute

20:39

adrenal washout more than 60 and relative more

20:41

than 40 is suggestive of an adrenal adenoma.

20:44

Another caveat from a protocoling perspective is

20:47

that if the patient does not have anything in the

20:49

rest of the scan, or you have already evaluated,

20:52

uh, the rest of the organs on, uh, uh, an earlier

20:55

CT, you can restrict the scan to cover only the

20:58

adrenal glands to avoid radiation to rest of

21:01

the body tissues. Coming to pheochromocytomas—

21:05

These are neural crest origin

21:07

tumors, and they arise from the medulla.

21:09

Commonly, they present with new-onset

21:12

malignant secondary hypertension,

21:14

as they secrete catecholamines.

21:17

Uh, this is famously known as the 10%

21:19

tumor, uh, and it's commonly asked

21:22

in the exams by the examiners.

21:25

So 10% of the pheochromocytomas are extra-adrenal.

21:29

A common location for this is the organ of Zuckerkandl,

21:31

uh, near the bifurcation of the aorta.

21:35

Uh, that's a common location for

21:37

extra-adrenal pheochromocytoma.

21:39

And you can also get them around the carotid body.

21:42

10% are bilateral.

21:43

10% tend to be malignant. On imaging,

21:46

there is no specific feature to suggest a

21:49

benign versus a malignant pheochromocytoma.

21:52

The only reliable sign is metastasis at presentation.

21:56

10% are seen in children.

21:57

It was thought that 10% are familial.

21:59

But now, uh, recent studies have shown

22:02

that up to 30% of pheochromocytomas can be

22:05

familial, uh, and 10% can show calcification.

22:09

It's very difficult, uh, to diagnose these on imaging,

22:12

because they can have, uh, different appearances.

22:15

There's no, uh, absolute specific

22:17

sign for pheochromocytomas.

22:19

So they're also known as imaging chameleons.

22:23

60–65% of the patients show, uh, what is known

22:26

as the light bulb sign on T2-weighted images,

22:29

because of the, uh, bright T2 appearance.

22:32

So for example, if you see this case, this

22:34

large left, uh, suprarenal lesion, it's fairly

22:38

heterogeneous with areas of cystic changes.

22:41

There's some area of enhancement.

22:42

I have another post-contrast image

22:44

later, but I can show you that.

22:46

So this was a left adrenal pheochromocytoma.

22:50

One imaging appearance which I have

22:52

found very useful is the enhancement

22:56

patterns of pheochromocytomas.

22:58

There are very few lesions which show intense arterial

23:01

enhancement, so that I have found very useful to

23:04

diagnose pheochromocytomas, be they, uh, uh, uh,

23:07

in the adrenal or even extra-adrenal locations.

23:12

So this is, uh, a patient, uh,

23:16

with multiple abnormalities.

23:18

And I'd like to, uh, I'd like you

23:20

to chat the, uh, diagnosis in the chat.

23:23

Uh, I don't have a poll for this, but

23:24

if you see, this is a non-contrast CT.

23:27

This is probably an arterial or late

23:30

arterial CT, and this is an MRCP image.

23:34

I will give a couple of, uh, seconds

23:37

for you guys to attempt this.

23:39

So what we see here is this intensely

23:41

enhancing right adrenal lesion.

23:44

There is this exhibit.

23:46

Left renal lesion and probably something here

23:49

as well, a couple of pancreatic cysts in here.

23:53

The liver also shows some cysts.

23:55

There are some renal cysts, multiple pancreatic

23:58

cysts, so multiple pancreatic cysts, renal

24:01

cysts, liver cysts, and, uh, an adrenal

24:05

lesion and probably solid renal lesions.

24:08

So this was a case of VHL, as quite a

24:11

few of you have rightly pointed out.

24:13

So among the 10% familial pheochromocytomas, which is

24:18

debated and can be up to 30%, these are the syndromes

24:22

associated with the familial pheochromocytomas.

24:25

You can take a, a screenshot

24:26

of this and go over it later.

24:30

This intense arterial enhancement.

24:33

Remember this because this is fairly typical

24:35

for an adrenal pheochromocytoma on CT.

24:40

Moving on to the malignant, uh, cortical tumor.

24:42

That's adrenal cortical carcinoma.

24:45

Uh.

24:46

The one thing that you have to remember about, uh, uh,

24:49

this lesion is that these lesions are large. Whatever

24:53

cases I have seen and whatever has been described

24:55

in literature, the one thing that is constantly

24:57

associated with these is that these are very large at

25:00

presentation and can go up to, uh, uh, typically more

25:03

than six centimeter in size. Because of their large

25:07

size, uh, they commonly alter their blood supply.

25:10

So a large amount of necrosis, hemorrhage,

25:13

and enhancement is quite common.

25:15

So, for example, if you see this large

25:18

right adrenal lesion, which was seen in a patient

25:21

presenting with right upper quadrant pain.

25:23

Uh, we gave a differential.

25:26

Uh, we gave multiple differentials, but because there

25:28

was no prior imaging, we suggested a biopsy, and

25:31

this turned out to be an adrenal cortical carcinoma.

25:34

Uh, the other, uh, uh, interesting fact is that a lot

25:37

of these patients, uh, uh, have, uh, functional, uh,

25:41

a lot of these carcinomas have functional, uh, tissue.

25:44

So in up to 60% of the cases, they can

25:47

have, uh, say, Cushing—either Cushing syndrome,

25:49

uh, which is most commonly described, or, uh,

25:52

Conn syndrome—that is, uh, increased aldosteronism.

25:58

Adrenal mets.

25:59

There's no specific imaging feature for adrenal mets.

26:03

Uh, but they're known to be, uh, very common because

26:05

of the rich blood supply of the adrenal gland.

26:08

The most common tumor is lung cancer.

26:11

And whenever you're reporting, uh, a chest CT and

26:14

you, you, you see a mass on the, uh, CT thorax,

26:18

always try to look at the adrenal glands and

26:20

mention it, uh, in your report if the adrenal

26:22

glands are normal or do you see a lesion in there?

26:25

Because metastases to the adrenals are quite

26:27

common in these, uh, lung cancer patients.

26:31

These are usually bilateral, and the left gland is

26:34

affected more than the right for unknown reasons.

26:36

So for example, if you see this case, this patient

26:38

had lung cancer. There is this large heterogeneous

26:41

left adrenal lesion, and there's a smaller

26:45

right adrenal lesion.

26:47

So no specific imaging features, but if

26:49

there is a known malignancy, that's the

26:51

first thing that you should be thinking of.

26:53

If there are no diagnostic imaging features, uh,

26:56

say of a benign tumor such as an adenoma or a myelolipoma,

26:59

as we discussed earlier, an important thing to

27:03

remember is that it's very, very, very unlikely for an

27:09

incidentally detected adrenal lesion to be metastasis.

27:13

So first presentation of an unknown malignancy

27:15

as, uh, an adrenal met is very, very rare.

27:19

In fact, a study done at MD Anderson, they

27:21

found only two out of around 1600 cases,

27:25

uh, to be an incidental adrenal met.

27:28

And that too, those were large,

27:29

more than six centimeter lesions.

27:32

An important pitfall is that, uh, metastases from RCC

27:36

and HCC can show washout in the

27:38

range of adrenal adenoma spectrum.

27:41

The other important caveat is that, say, a

27:44

renal cell carcinoma can have fat within it,

27:46

and the metastasis will mimic the primary.

27:49

So you may see fat in an adrenal lesion,

27:52

uh, uh, but you have to look at the entire

27:54

lesion as a whole, uh, to determine whether

27:57

it's a met or a benign myelolipoma.

28:01

Moving on to hyperdense lesions, uh, the important,

28:05

uh, uh, lesion in this category is hemorrhage.

28:09

Adrenal calcifications are mostly rare.

28:12

Uh, they're commonly post-hemorrhage,

28:15

post-hemorrhage, or, uh, say in a tumor

28:17

such as an adrenal cortical carcinoma.

28:21

So adrenal hemorrhage is most commonly

28:23

seen in neonates, but in adults it

28:25

can be traumatic or non-traumatic.

28:28

When it's traumatic, it's usually unilateral.

28:31

And when non-traumatic, it's bilateral.

28:32

And the common causes are coagulation disorders,

28:35

hemorrhagic diathesis, or stress.

28:38

So if you see this.

28:39

Round, slightly hyperdense, right

28:42

adrenal lesion in this patient.

28:44

This was adrenal hemorrhage.

28:47

So the reason why the right adrenal gland is affected

28:50

more in cases of, uh, traumatic hemorrhage, uh, is

28:53

something, uh, that's got to do with the anatomy.

28:56

As I told you before, the right adrenal vein is

28:59

fairly short, while the left adrenal vein is long.

29:03

So imagine, uh, whenever there are these shear

29:05

forces, uh, in trauma and the adrenal glands

29:09

are compressed against the spine, uh, the right

29:12

adrenal gland, because of the short adrenal, uh,

29:15

vein, does not have much scope for movement.

29:17

So that's why, uh, the, the right adrenal gland

29:21

is commonly affected in traumatic hemorrhage.

29:24

But as the left adrenal vein has significant

29:26

scope for movement and is away from the spine,

29:29

so that's why the left adrenal

29:30

gland is less commonly affected.

29:33

So traumatic adrenal hemorrhage compared to

29:35

other, uh, important organs in the abdomen

29:38

is, uh, uh, rare, but it's underreported.

29:42

It's associated with a higher CV, uh,

29:44

higher severity of other organ, uh, and it's

29:48

associated with higher mortality rates,

29:50

because, uh, we have two adrenal glands.

29:53

Very rarely are these associated with

29:55

adrenal insufficiency and crisis.

29:58

So, for example, if you see this case, this

30:00

patient has a large liver laceration, a

30:02

small splenic laceration, and that was a

30:05

small perirenal right adrenal hemorrhage.

30:09

The typical imaging appearance has been described as

30:12

a three centimeter round or ovoid hyperdense mass.

30:15

In subtle cases, uh, all you'll see is, uh,

30:19

hyperdensity around involving the adrenal

30:21

gland and some stranding in the ENT fat.

30:25

The important thing to remember is that these

30:27

should decrease on follow-up imaging, and

30:29

the attenuation should resolve with time.

30:32

So this was a patient who had a splenic

30:34

laceration, uh, and a large left adrenal

30:38

and perirenal hematoma after, uh, MVC.

30:43

So for, as like for other organs, even the

30:46

adrenal, uh, organ injury scale has been described.

30:49

You can go over this, you can take a screenshot

30:50

of this and whenever you're reporting,

30:52

and if you see an adrenal injury, you can

30:54

use this, uh, classification to grade it.

31:00

Um, so for non-traumatic adrenal

31:02

hemorrhage, uh, it's important to remember

31:04

this concept known as the vascular dam.

31:06

So the adrenals are very rich in blood supply.

31:10

You can, uh, imagine by the kind of hormones it

31:12

supplies, uh, the, the, the fight and flight hormones.

31:16

So, uh, uh, it's a, uh, very vascular organ.

31:20

We have three

31:21

arteries supplying both adrenal glands.

31:24

These break down into capillaries, and at the

31:27

level of the corticomedullary junction, we

31:29

have very few, uh, venules, and ultimately they

31:33

drain into a single adrenal vein bilaterally.

31:37

So this creates what is known as a

31:38

bottleneck effect or an adrenal dam.

31:42

This is exaggerated in cases of, uh,

31:46

in cases of, uh, stressful situations.

31:48

So what happens is that there's increased blood

31:51

supply to the adrenal and there is venous constriction.

31:54

So this creates a bottleneck, which can lead, uh,

31:58

uh, which can lead to either hemorrhage or thrombosis

32:01

of the vein and secondary hemorrhage after thrombosis.

32:05

So this is, this concept is known

32:07

as the adrenal vascular dam.

32:09

Uh, and the reason for that is the rich

32:12

arterial supply and the sparse venous drainage.

32:16

So that's the bottleneck effect or vascular dam.

32:20

Non-traumatic adrenal hemorrhage.

32:22

The causes, uh, include stress of any

32:24

kind, such as surgery, organ failure,

32:27

sepsis, or even pregnancy bleeding.

32:29

The diathesis, uh, is also an important cause, uh, and

32:34

procedures such as venous sampling or nephrectomies.

32:37

So, for example, if you see this patient, uh,

32:39

there's bilateral adrenal hemorrhage, uh, and

32:42

this patient was on anticoagulant therapy.

32:47

One important thing to remember, uh,

32:50

is even adrenal tumors can bleed.

32:53

The most common ones that bleed are myelolipomas,

32:56

hemangiomas, pheochromocytomas, or cortical carcinomas.

33:00

Uh, and here's where MRI can prove, uh, to be useful.

33:04

So if you see, uh, an adrenal hemorrhage,

33:06

uh, in a patient, especially if it's

33:08

unprovoked, there's no history of trauma.

33:10

There are none of the, uh, uh, uh, the

33:13

conditions that we discussed for adrenal.

33:15

He, uh, non-traumatic hemorrhage, such

33:17

as, uh, uh, coagulation disorders.

33:20

If the patient does not have any of those, we'll make

33:23

sure that we'll at least follow the patient on CT.

33:26

And if not, uh, we'll suggest an MRI with contrast.

33:30

So, for example, in this patient, uh, the one

33:33

with pheochromocytoma that we discussed earlier,

33:36

you see the subtle T1 hyperintensity.

33:39

And there there are areas of, uh, this was

33:41

suggestive of hemorrhage, and then there

33:43

are peripheral solid enhancing areas.

33:45

So this is not.

33:47

A simple adrenal hemorrhage.

33:49

So this was a case of ochre cytoma,

33:51

which presented with hemorrhage,

33:56

the signs that they have described.

33:58

Uh, for, uh, imaging just on CT, it's obviously very

34:01

difficult, but if you have a non-contrast CT that

34:04

helps to determine if there is any focal enhancement.

34:08

Intraregional calcifications are usually not

34:10

seen with acute hemorrhage, so that should raise

34:12

a possibility for, uh, tumoral hemorrhage, and

34:15

make sure that you follow up or suggest an

34:18

MRI for these lesions. Diffuse abnormalities

34:22

include hyperplasia, which we commonly see.

34:24

For example, this was a patient with breast

34:27

cancer presenting with a liver met.

34:30

Uh, we see these adrenal glands are, uh,

34:33

slightly bulky as compared to, uh, the normal

34:35

ones, which we saw earlier.

34:38

Uh, in most cases, these are incidental and are not

34:41

of much value, uh, if these have a nodular appearance.

34:44

So if you see a focal abnormality, that's

34:46

when you should start getting concern.

34:48

But in most cases, uh, on imaging, uh, the ACR does

34:53

not recommend any particular, uh, recommendation

34:56

for, uh, these bilateral adrenal hyperplasias.

35:02

Moving on to another diffuse abnormality.

35:05

This patient presented, uh, with multiple liver mets.

35:08

The primary was unknown and unfortunately, within a

35:11

span of three months, her condition worsened, and you

35:14

see that the metastases have worsened significantly.

35:18

The adrenals were fairly hyperenhancing.

35:21

See if you see this, these adrenals

35:22

before and now they're showing significant

35:25

enhancement. There is some mucosal enhancement

35:28

involving these small bowel loops.

35:30

So this was a case of CT hypoperfusion complex.

35:34

This patient was in septic shock,

35:36

although our case was not that florid.

35:38

Uh, but this is a case from AJR, uh, in this article

35:42

where they described the CT hypoperfusion complex.

35:45

So whenever there is hypoperfusion or

35:47

shock due to any cause, these are the signs,

35:50

uh, that are commonly seen, uh, and that

35:52

includes hyperenhancing adrenal glands.

35:58

So MRI is a problem-solving tool.

36:00

I have a, uh, a couple of quiz questions here.

36:03

I'm sure most of you, uh, will get this right,

36:06

but just to make sure that, uh, our concepts

36:08

are clear, uh, I'll do a couple of polls here.

36:10

So, uh, if you can get, uh,

36:12

question number five for the poll.

36:14

So the question here is, which

36:17

of this is a fat-saturated image?

36:19

Is it A, is it B, is it both

36:22

A and B, or neither A and B?

36:35

This question may be fairly basic for most of you

36:37

who do a lot of body imaging, but for the R

36:41

ones, R twos, and R threes who are attending this talk,

36:44

uh, this will clear a few concepts.

36:52

Perfect.

36:53

So.

36:54

53% have got, you got this one right.

36:57

And around 50%, uh, have, uh, got it wrong, but we'll

37:00

go over this, uh, just to clear this concept.

37:04

So moving on to the next question.

37:07

So the question remains the same.

37:10

So, uh, the question changes, but the

37:12

options and the images remain the same.

37:14

So this, what is the right question?

37:16

So which of the following is an opposed-phase image?

37:21

Is it A, is it B, neither A

37:23

or B, or is it both A or B?

37:30

So in most cases, CT is sufficient, uh, for

37:33

classifi– uh, for, uh, evaluation of adrenal

37:36

nodules for most of them that we diagnose.

37:39

And in rare cases, we may need to do an MRI.

37:53

So 80% have g– have of you have got this right.

37:56

So this, uh, is not, none of them is a fat–

37:59

saturated image because you see the, uh, the

38:02

subcutaneous and abdominal fat in both sequences.

38:06

The second question was, which of the

38:08

following is an opposed-phase image?

38:10

So if you see this rim of hypointensity

38:14

around abdominal organs, that is known

38:17

as the India ink artifact, uh, which

38:20

is seen in the opposed-phase imaging.

38:24

So just to revise, this is a fat-saturated T1 pre-

38:28

contrast image where you see the abdominal and, uh,

38:33

the subcutaneous and abdominal fat being suppressed.

38:36

And this is what is known as a chemical

38:38

shift or an opposed-phase imaging.

38:41

The importance of this is that fat saturation

38:44

or STIR imaging is used to detect macroscopic

38:47

fat so that in, in terms for adrenals.

38:51

Fat in a myelolipoma will get suppressed

38:54

on fat-saturated or STIR images.

38:57

On the other hand, chemical shift

38:59

imaging detects intracytoplasmic fat.

39:02

So see, an adenoma fat in an adrenal

39:06

adenoma will be get — will suppress — will

39:08

get suppressed on chemical shift imaging.

39:10

So that's the concept that I wanted to drive home.

39:14

So, uh, what happened is, like this,

39:16

uh, so MRI in most cases, as I said,

39:18

is used as a problem-solving tool.

39:20

This patient had these incidental bilateral adrenal

39:23

nodules while she was undergoing a MRI spine.

39:26

Uh, the tech noticed this and asked her.

39:28

So what we did was we suggested an opposed-phase

39:32

scan, uh, as the patient was on table.

39:35

So you see these T1 iso-intense

39:37

bilateral adrenal lesions, and on the a-

39:39

post-phase, both of them show signal drop.

39:42

So that is characteristic for adrenal adenomas.

39:46

So if you have a patient who has a CT Houns-

39:49

field, uh, value of more than 10 H2.

39:52

Uh, and if you're not, like, if you prefer

39:54

to do, uh, chemical shift imaging over a

39:57

CT adrenal protocol, uh, in those cases,

40:00

intracytoplasmic fat in cases of adrenal adenomas

40:04

will get suppressed on out-phase imaging.

40:06

An important caveat to remember is that at any

40:10

point, if there was a choice, if you wanted to

40:12

do chemical shift imaging versus, uh, CT, uh,

40:16

dynamic CT, the preferred tool is dynamic CT,

40:20

because ultimately we are diagnosing, uh, the

40:23

same thing — the presence of intra-abdominal fat.

40:27

Intracytoplasmic fat in cases of adenomas — it's been

40:31

shown that in lesions which have more

40:34

than 20 or 30 Hounsfield units on non-contrast

40:39

CT.

40:41

CT dynamic — dynamic CT has performed

40:44

better than chemical shift imaging.

40:47

So moving on to the protocol, you

40:49

should include a chemical shift of

40:51

imaging — that is, in- and out-phase imaging.

40:53

You should include a T2-weighted, uh, study to just

40:56

look, uh, at the T2 characteristic of the lesion.

40:59

A T1 fat suppression will help

41:01

you diagnose macroscopic fat.

41:03

And an in-phase T1, uh, image is just like your T-

41:08

1 image, so you don't need to do a T1 separately.

41:11

And dynamic post-contrast would be optional depending

41:14

on the findings, uh, on your pre-contrast studies.

41:18

So just like, uh, adrenal washout on CT,

41:21

uh, there are, there are these, uh, indexes,

41:25

indices that have been described on MRI.

41:28

You can go over this later, uh, uh, just to save time.

41:32

Uh, I will move on to the next slide and try

41:34

to cover more, uh, pathologies, and this you

41:36

can discuss later if there are any questions.

41:39

So, a common, uh, problem that we face

41:42

is to distinguish incidental adrenal

41:45

lesions in patients with known cancers.

41:48

Uh, it's difficult if there are

41:51

no, uh, no signs on, uh, the — none

41:53

of the signs of, uh, the typical — say, an

41:57

adenoma or myelolipoma — are not present.

41:59

Uh, a couple of signs that have been described on

42:02

T2-weighted imaging is that metastases tend to

42:05

be more hyperintense on T2, and they tend to be

42:08

heterogeneous, although this depends on the size of

42:11

the lesion and the primary, but this is something that

42:14

would, uh, help you suggest biopsy in certain cases.

42:18

Another important role of MRI is in cases,

42:21

uh, to evaluate unprovoked adrenal hemorrhage.

42:25

So for example, in this patient, he was a young

42:27

patient presenting with a large left adrenal hematoma,

42:30

no history of trauma or other predisposing factors.

42:34

So we suggested a follow-up MRI.

42:36

You can see this T2 hyperintense area with fluid,

42:39

fluid levels, and on post-contrast subtraction images,

42:43

there's no enhancement.

42:44

So whenever you're evaluating an adrenal

42:46

lesion for suspected tumoral hemorrhage, make

42:49

sure that you include subtraction images.

42:54

Moving on to approach to

42:55

address adrenal incidentalomas.

42:58

So adrenal incidentaloma is any lesion, which is

43:01

more than one centimeter found incidentally on an

43:05

imaging study. For lesions less than one centimeter,

43:09

the ACR does not recommend any further workup.

43:12

You can follow this guideline from ACR,

43:15

or you can choose if your institution

43:18

uses a different, uh, algorithm.

43:21

But make sure that everybody, like all your

43:23

entire radiology group, sticks to one algorithm.

43:27

I use the ACR algorithm, and

43:30

we will go over this quickly.

43:33

So if you diagnose, uh, if you see a more

43:36

than one centimeter adrenal mass on CT or

43:38

MRI, look for the typical imaging features.

43:43

Is there macroscopic fat?

43:45

Is there calcification?

43:47

Is the entire lesion calcified?

43:49

Some calcification, uh, again, that

43:52

would not, uh, be fairly specific.

43:54

Is the lesion less than 10, 10 Hounsfield units in a

43:57

non-contrast CT, or is there signal drop on the out

44:01

of phase, uh, MR images? All these are suggestive

44:05

of benign lesions, irrespective of the size.

44:08

And no further follow-up is suggested.

44:11

What if the imaging is not, uh, classic

44:15

for any of the, uh, adrenal lesions?

44:18

In those cases, when the lesions are large

44:21

and anywhere more than four centimeters,

44:23

those tend to be more, uh, worrisome.

44:25

So in that case, we'll suggest either

44:29

a PET CT or biopsy or resection if

44:32

there's no history of malignancy.

44:35

Moving on to these one to four centimeter lesions.

44:38

If these are small, say one to two

44:40

centimeters, then you can follow up in

44:43

12 months with adrenal protocol CT.

44:46

If they are more than two to four centimeters,

44:49

then you can use either the, uh, you can do a

44:52

dedicated adrenal protocol CT or, depending on, uh,

44:56

the appearance of that, you can go ahead and, uh,

44:58

either do chemical shift imaging or dynamic imaging.

45:03

So, for example, this case, this patient

45:05

was again a, uh, known breast cancer

45:07

presenting with multiple level lesions.

45:10

We have this more than one centimeter incidental

45:14

left adrenal lesion, but it has macroscopic fat.

45:18

So we don't need to be worried about this.

45:20

And this was an adrenal myelolipoma.

45:23

Um, and we don't need to do anything,

45:25

uh, in terms of this left adrenal lesion.

45:30

So, uh, adrenal glands, uh, are known to be, uh,

45:34

uh, there's known physiologic hypertrophy and

45:37

hyperplasia of the adrenal glands, which makes

45:39

them susceptible to ischemia and hemorrhage.

45:42

For example, this patient presented with

45:44

left upper quadrant pain.

45:47

We found this lesion on ultrasound.

45:50

So in pregnancy, the first, uh, in a

45:52

pregnant patient, your first investigation

45:54

should always be an ultrasound.

45:55

And if, uh, ultrasound is not very helpful, you

45:59

can always further characterize with an MRI. But

46:02

contrast is contraindicated, uh, in most cases.

46:05

So all you can do is a non-contrast

46:08

MRI and then follow up the patient.

46:10

So we follow up.

46:11

So we did a MR, uh, non-contrast study.

46:14

There were these areas of T2 hyperintensity.

46:16

So this was adrenal hemorrhage, uh, just to make sure

46:19

that there's nothing, uh, there's no underlying mass.

46:22

We did a follow-up, uh, and this lesion had decreased

46:25

in size, so that was suggestive of adrenal hemorrhage.

46:29

Adrenal infarction has also been reported,

46:31

but, uh, there's not no specific sign apart

46:34

from edema, uh, appearance and restricted

46:37

diffusion of the adrenal glands. Coming to few

46:40

adrenal, uh, rare adrenal pathologies.

46:44

Adrenal infarction has also been reported.

46:46

For example, in this patient with aortic dissection,

46:49

you see that the adrenal glands do not show any

46:52

enhancement, but the peripheral portions are slightly

46:55

hyperdense compared to the rest of the gland.

46:58

So this is what is known as the

47:00

cortical rim sign in adrenal infarctions.

47:04

So if you see this, uh, journal case, I know it's very

47:07

difficult to appreciate, but because the peripheral

47:09

portions of the adrenal glands are supplied by

47:12

capsular arteries, they're spared in cases of, uh, uh,

47:16

a systemic, uh, issue with adrenal arterial supply.

47:20

So that is, uh, known as the cortical

47:22

rim sign in adrenal infarction.

47:25

Adrenal infection is rare, uh, uh, as

47:29

an isolated finding, but in cases of, uh,

47:32

multi-systemic involvement, especially in cases

47:35

of tuberculosis, adrenal infection is known.

47:38

So, for example, if you see this patient, both

47:40

adrenal glands show a few hyperintense areas.

47:43

There's this suspected left adrenal lesion.

47:47

This patient had bilateral tubo-ovarian abscess,

47:50

multiple bony lesions, and necrotic periportal nodes.

47:55

So this was an adrenal

47:57

infection in cases of tuberculosis.

48:00

Although tuberculosis and other infections

48:03

are rare in North America, but, uh, in

48:06

the developing countries, tuberculosis is

48:09

the leading cause of Addison's disease.

48:13

This case is courtesy Dr. Nick Sheer.

48:15

Uh, this was a patient who had developed

48:18

this large heterogeneous right adrenal

48:22

mass. So this was adrenal lymphoma.

48:24

Again, uh, it's very difficult to diagnose

48:27

these, uh, uh, when you are, when you are

48:30

seeing them first, but any lesion, which is more

48:32

than four centimeters and is new as compared to

48:35

your prior imaging, should get you concerned.

48:39

Another pathology, which I've seen

48:41

at least two cases of, are ganglioneuroma.

48:44

So these are neurogenic, neurogenic tumors,

48:46

which are on the benign spectrum, uh, of, uh,

48:49

neuroblastoma, which is a pediatric tumor.

48:52

So, uh, in this patient, if you see these

48:54

bilateral, slightly hypodense lesions, uh,

48:58

that's one, uh, diagnosis you could think of.

49:00

But again, uh, this is not

49:01

something that we see commonly.

49:03

Other rare pathologies include, uh, lymphangio-,

49:07

hemangiomas, but all of them are very, very rare.

49:12

Uh, collision tumors are adrenal tumors when there

49:15

is more than two histologically distinct tumors,

49:18

and the most common ones described are adrenal mets

49:22

in cases of adenomas. Uh, it's very difficult again

49:26

to distinguish in imaging, but an important sign

49:28

is that, uh, if on chemical shift imaging, the

49:32

fat suppression is not homogeneous.

49:34

That is one of the signs described

49:37

to distinguish a collision tumor.

49:39

So, for example, if you see this lesion, a portion

49:42

of this is getting suppression, the out-of-phase

49:44

image, but, uh, some of it is not getting suppressed.

49:48

So that should make you think of collision tumors.

49:51

But again, these are very rare, and the

49:53

incidence is reported in about 2% of cases.

49:56

And if you have prior imaging, that is helpful.

50:00

So let's have a few review questions just

50:03

to revise whatever concepts that we learned.

50:05

So let's bring up question number seven.

50:11

So which of the following is the ideal protocol for

50:14

evaluation of a two-centimeter adrenal nodule with

50:17

a Hounsfield value of plus 30 on non-contrast CT?

50:23

So is it chemical shift MRI?

50:26

Is it non-contrast, arterial, and delayed phase?

50:29

So around 61% of you have got it right.

50:31

So the correct answer in this case is

50:33

number four, which is a non-contrast,

50:36

portal venous, and delayed phase CT.

50:39

For those who said chemical

50:41

shift MRI, you're not wrong.

50:43

That's also a partially right answer.

50:45

But if you remember during my talk, I mentioned

50:47

that when the Hounsfield value is more than

50:50

30, chemical shift imaging is not very, uh,

50:54

specific for diagnosis of adrenal adenomas.

50:58

So when the Hounsfield value is, say, between, uh,

51:01

10 to 20, they're helpful, but once the Houns-,

51:04

once they start getting dense, more than 20, the

51:07

amount of intracytoplasmic fat is not enough

51:10

to be suppressed on chemical shift imaging.

51:12

So the correct answer is number four. And remember

51:16

that the delayed phase has to be 15 minutes, and it's

51:20

the portal venous phase and not the arterial phase.

51:24

Moving on to the next review question.

51:26

So if we can have question number eight.

51:29

Which of the following is not true

51:32

about a traumatic adrenal hemorrhage?

51:36

Is it number one?

51:37

Left adrenal gland is more affected than the

51:39

right, associated with higher mortality,

51:42

rates associated with more severe injury,

51:45

or adrenal insufficiency is uncommon?

51:49

I had to rush, uh, through the second part of the lecture

51:52

just to cover, uh, these review questions because, uh,

51:56

I wanted to talk more about the common, uh, uh, issues

52:00

and then the rare ones we can obviously discuss, uh,

52:02

depending on, uh, how many questions you guys have.

52:05

So, perfect.

52:06

So 60% of you have got it right.

52:09

Uh, the right adrenal gland—

52:11

if you remember, I described the anatomy.

52:14

The right adrenal gland is more commonly

52:17

affected than the left adrenal gland,

52:18

and that has got to do with the anatomy.

52:21

The right adrenal gland is close to the spine,

52:23

and the right adrenal vein is shorter, so

52:26

that makes it more prone to shearing forces.

52:31

Moving on to the next question.

52:32

So, this patient, uh, had breast cancer and

52:36

presented, uh, with a left adrenal nodule on CT.

52:42

The average attenuation on this—

52:45

see portal venous phase is around 46 Hounsfield units.

52:52

So what would be the next best step?

52:57

Is it suspicious for mets?

52:59

Is it just a benign adenoma and no further workup?

53:02

Would you suggest a non-contrast CT or would

53:04

you suggest a dedicated adrenal protocol CT?

53:13

Perfect.

53:13

So, uh, most of you have got it right—around 62%

53:17

have mentioned, uh, suggest adrenal protocol CT.

53:21

There are two right answers in this case.

53:23

Uh, the perfect answer would be just to do a

53:26

non-contrast CT because if this lesion shows Houns-

53:30

field value of less than 10 HU on a non-contrast

53:33

CT, we may not need the rest of the, uh, scan.

53:36

But if you said number four, that's also right.

53:39

Uh, that's what we did.

53:41

So this patient with the non-contrast CT had—

53:43

attenuation of minus six.

53:46

But unfortunately, there was—there was no rad on site.

53:49

Uh, so, uh, the tech had to go ahead and,

53:51

uh, had to, uh, do the entire protocol.

53:54

But remember that, uh, we should try to protocol

53:57

these, uh, when there's a radiologist on site,

53:59

just to have a look at the non-contrast CT.

54:02

And if there's non-contrast

54:04

attenuation is less than 10 HU,

54:06

we don't need to do the further workup.

54:11

This is one of our last questions.

54:13

So again, incidental right adrenal lesion.

54:18

Next step: Is it suspicious for mets?

54:22

Is it a benign adenoma?

54:23

No further follow-up.

54:25

Is it a benign myelolipoma?

54:27

No further follow-up. Or should we

54:28

do a dedicated adrenal protocol

54:30

CT?

54:34

Okay, so most of you have got it right.

54:36

What we see here is this—

54:38

right adrenal lesion with macroscopic fat.

54:40

So this lesion has intensity

54:43

similar to the retroperitoneal fat.

54:45

So a benign myelolipoma.

54:47

That's the correct answer, as most of you have

54:49

got it right.

54:49

So this is our last question.

54:53

This patient presented with accelerated hypertension.

54:56

What is your diagnosis for this right adrenal lesion?

55:01

Is it an adrenocortical carcinoma?

55:03

But remember that those are large,

55:05

heterogeneous lesions, and they would not

55:07

show that much enhancement. Adrenal mets—

55:10

it could be difficult to say.

55:12

Could it be a ganglioneuroma?

55:14

Uh, those lesions—we saw that they

55:16

tend to be hyperintense.

55:19

Uh.

55:20

So the diagnosis in this case is an adrenal

55:24

pheochromocytoma, and we'll have our

55:27

poll results, and 96% have got it right.

55:30

The clinical history helps in this case.

55:32

So accelerated hypertension in a patient

55:34

with intensely enhancing right adrenal

55:36

lesion—pheochromocytoma is the right answer.

55:42

So, pitfalls.

55:43

Most of them we have discussed, uh, uh, in

55:46

our talk, so we'll not waste time on that.

55:49

Uh, just to reiterate a few key points.

55:52

Attenuation of less than 10 Hounsfield

55:54

units on a non-contrast CT—adrenal adenoma.

55:58

No further imaging. Macroscopic

56:00

fat—adrenal myelolipoma.

56:02

Again, no further imaging.

56:04

If the Hounsfield unit is, say, more than 10 HU

56:07

but less than 20, you can do chemical shift

56:10

imaging just to avoid radiation to the patient.

56:13

But if it's more than 20, uh,

56:15

adrenal protocol CT is preferred.

56:18

If the Hounsfield value is more than 43

56:21

and there's no calcification or

56:23

hemorrhage, that is a worrisome lesion.

56:26

So make sure that that gets investigated in detail.

56:29

Large lesions are worrisome and that should make you think

56:31

of metastasis, adrenocortical carcinomas, or even

56:34

pheochromocytomas. Lesions less than one centimeter

56:37

should not be pursued according to the ACR criteria.

56:40

But that should depend on, uh, the presentation, known

56:43

malignancy, and your individual hospital protocol.

56:46

And one caveat, which is, uh, true

56:49

for anything in radiology, is always

56:50

compare to priors whenever possible.

56:54

So, a quick recap.

56:55

We went over the imaging anatomy.

56:56

We discussed a few focal abnormalities and an approach

56:59

depending on the CT appearance, a couple of diffuse

57:02

abnormalities, and we talked about a few zebras—

57:05

pediatric pathologies we did not cover in our talk.

57:08

Uh, those are my references, and, uh, thank

57:12

you everyone for listening to me patiently.

57:18

If you're on Twitter, you can follow me.

57:19

Uh, that's my handle. That's my website.

57:21

So you can check this out.

57:22

Uh, yeah.

57:27

Well, thank you very much, Dr. Ari.

57:30

Um, I see we do have some questions in

57:32

the Q&A. Would you like to, um—sure.

57:35

Open those up.

57:38

Um, why are adrenal mets more common

57:40

in lung cancer than others?

57:42

I'm not, uh, sure about the exact

57:44

pathology, but adrenals are one of the—

57:46

most common sites for lung cancer mets.

57:52

Uh, this is a good question.

57:53

So, on many CTs, one sees thickening of

57:55

the, uh, limbs of the adrenal glands,

57:57

uh, without a rounded morphology.

57:59

How do you dictate these?

58:00

So, in those cases, I tend to, uh, dictate

58:03

these as non-specific adrenal thickening.

58:06

In most cases, you may see, uh,

58:09

uh, these to be hypertensive.

58:10

These could be lipohyperplasia, but, uh...

58:15

Uh, in most cases, I just, uh, mention that at

58:17

the body of the report that there's non-specific

58:19

thickening and there's no focal nodule.

58:22

If you have a prior to compare,

58:23

uh, that is, uh, that helps.

58:26

But if there's just non-specific

58:27

thickening, I just mention that—no nodules.

58:32

Uh, another question is, uh, should we

58:34

report nodules less than 10 millimeters?

58:37

Uh, we should report them, but I would not give them

58:40

a lot of weightage, especially in the impression of

58:42

the report if the patient has a known malignancy.

58:46

If this is a new lesion, if this is

58:48

growing from a prior study, I would

58:50

definitely, uh, raise a suspicion.

58:52

But if it's an incidental less than

58:53

10 millimeter lesion, the ACR doesn't

58:56

suggest, uh, uh, following these up.

59:00

This is an interesting, uh, question by Dr. Amin.

59:03

So can we use the same formulas for absolute

59:05

and relative washout in MRI? Is the volume of

59:08

MRI injected, uh, affect the measurements?

59:11

Uh, MRI has its, uh—I'm not sure, uh, about this

59:16

question, and, uh, that would be an interesting study

59:18

to do. But in MRI, these—in my knowledge, they

59:22

have not been, uh, described to use the same, uh, uh,

59:25

washout characteristics as on the CT dynamic study.

59:30

Dr. Denver, uh, suggests, does dual

59:32

energy CT help in diagnosing adenomas?

59:35

Uh, for sure.

59:35

They, uh, CT—if you have dual energy,

59:38

uh, most hospitals have dual energy CT.

59:41

And retrospectively what you can do is reconstruct

59:44

the study in, uh—reconstruct the non-contrast study.

59:48

And, uh, uh, if the Hounsfield value of, uh, the

59:51

nodule is less than 10 HU, uh, that can help.

59:54

You don't need to call the patient

59:55

back, uh, versus, say, a routine CT.

59:58

Uh, you'll have to call the

60:00

patient back for, uh, a non-contrast CT.

60:03

So if you have a dual energy CT, you can, uh,

60:06

reconstruct the image—virtual non-contrast

60:08

CT—and check the Hounsfield value in that.

60:12

So, uh, follow-up imaging after—

60:13

how much time is advised for a suspected

60:15

adrenal, uh, hemorrhage to rule out a mass?

60:18

Uh, I'm not sure if there are any set guidelines,

60:21

but, uh, if there is—if there is known adrenal

60:24

hemorrhage, if there's, uh, other signs of

60:27

trauma, uh, what we can do is, uh, uh, we—

60:31

that's probably adrenal hemorrhage we need not be

60:33

worried about. But if the adrenal hemorrhage is

60:36

non—like, if there's no predisposing factor, I

60:39

would, uh, suggest an MRI study right away.

60:42

And, uh, in other cases, at least a three

60:45

to six-month follow-up should be fine.

60:50

Okay.

60:50

Uh, can I repeat the vascular dam effect?

60:53

Uh, sure.

60:54

I'll try to go to that slide.

60:56

So, uh, as you know, adrenal

60:58

glands are fairly vascular.

61:01

Uh, to sum up the adrenal, uh—

61:02

the vascular dam effect is that

61:06

adrenals have a very good arterial supply, but

61:09

the venous drainage is, uh, via very small veins.

61:14

So if you can imagine, a lot of blood is

61:17

coming into the adrenal gland, but there

61:20

is not much, uh, scope for it to go out.

61:24

So what happens is that, uh, this is

61:26

exaggerated in cases of stress situations.

61:30

Uh, so there is intravascular congestion,

61:32

and that can lead to adrenal hemorrhage.

61:35

So hopefully that makes it a bit clearer.

61:40

Okay.

61:40

MRI diffusion can be helpful.

61:42

Uh, MRI diffusion definitely can be helpful,

61:45

uh, say, in cases of abscesses where it shows

61:48

restricted diffusion. It's also been shown to

61:50

be useful in cases of ischemia, but I'm not

61:52

sure, uh, if it's of value in cases of

61:56

adrenal adenomas versus other lesions.

62:03

So what percent—what is the percentage of signal

62:05

loss in in-and-out-of-phase images of an adenoma?

62:08

So, uh, that has been described,

62:12

uh, in terms of spleen.

62:14

So if you look at this, uh, image here—

62:16

so, uh, that is described with respect to

62:20

the spleen index or the, uh, CSI ratio.

62:24

So the lesion signal intensity on out-phase images and

62:28

in-phase images compared to that of the spleen.

62:32

So the signal drop of the lesion compared

62:34

to the signal drop of the spleen.

62:37

So if that ratio is less than 0.71,

62:39

that's suggestive of an adenoma.

62:41

The other.

62:43

Index used is the signal intensity index, where you see

62:47

how much is the signal drop, uh, of the lesion itself.

62:50

In this one, we do not compare it to the spleen.

62:53

And in this patient, if there's more than 16.5%

62:56

uh, signal drop, that is suggestive of an adenoma.

63:02

I think that answers all our questions.

63:06

Alright, well, as we bring this to a close,

63:08

I want to thank Dr. Ari for this lecture.

63:11

And thanks to all of you for

63:12

participating in our noon conference.

63:15

Reminder that this conference is

63:16

available on demand on MRIonline.com,

63:19

in addition to all previous noon conferences.

63:22

Be sure to join us tomorrow for a lecture from

63:25

Dr. Jordan on headache and neuroimaging.

63:28

You can register for that at MRIonline.com and follow

63:31

us on social media at MRIonline for updates

63:36

and reminders on upcoming noon conferences.

63:39

Thanks again, and have a great day.