0:01

Well, hello, everyone.

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Uh, my name is Marc Gosselin.

0:04

I'm a chest radiologist, uh, 20 years,

0:08

academics, uh, mostly at OHSU, um,

0:11

currently a cardiopulmonary radiologist and

0:14

general radiologist at Vision Radiology.

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So over the next, uh, uh, number of sessions here,

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we're going to go through cardiopulmonary imaging.

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Um, some of it you've probably been taught,

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but I'm willing to bet that a lot of it you have not.

0:29

Um, the approach is somewhat different,

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it's something I've worked through over my years

0:35

to effectively teach this complicated area.

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And so, um, let's see what you think.

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One of the quotes I usually go by is

0:44

the greatest optical discovery is not

0:45

ignorance, but the illusion of knowledge.

0:48

Okay, so this is the introductory one, and what

0:52

we're going to cover today is something really basic.

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When you're the perception of

0:56

abnormalities, mostly on a radiograph.

0:58

But, you know, we'll talk about CTs and maybe even

1:01

MRs too, and we're going to review the importance

1:04

of organ density and how we visualize things.

1:07

And then I'm also going to emphasize,

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and this is something that hasn't been

1:10

taught, the difference between a pathology

1:13

differential and an etiology differential.

1:16

And these are very different, but they are

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almost always combined, and this leads to a

1:20

great deal of confusion regarding reports and

1:24

an understanding of cardiopulmonary imaging.

1:27

So, when you're able to separate

1:29

pathologies and etiology on your reports,

1:31

it tends to be much more clear.

1:33

Uh, the clinicians understand it

1:35

as well as you understanding these

1:36

complicated things better within yourself.

1:40

It is my hope that in these sessions,

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we'll expose the old propagated myth that

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chest imaging is just long differentials.

1:47

No, it isn't.

1:49

Okay, concept one.

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The most important concept in all imaging.

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We see structures because

1:55

of a difference in density.

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That's it.

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The greater the difference in density,

2:00

the better we see the organ boundaries.

2:03

Okay, pulmonary vessels in the chest are well

2:06

seen because they have blood density, and it

2:08

has surrounding lungs, so we see them sharply.

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Branching throughout.

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When the lung becomes abnormal and

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starts to become opaque, then we

2:17

start to lose the visualization.

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Airways aren't seen in the lung because they're

2:21

filled with air, and it's surrounded by air.

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They're the same density, so you don't see them.

2:27

Okay?

2:28

So this is what I need you to start doing.

2:30

A lot of times we get taught to

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look at heart border or diaphragm

2:34

for some sort of pulmonary disease.

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That's not.

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But it's a nice concept, right?

2:38

You use the pulmonary vessels.

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Take a look.

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When you're looking here, start with

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the right pulmonary artery right here.

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You see the margin is really sharp.

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The left pulmonary artery, there's sharp.

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You can look at the on end vessels.

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They're nice and sharp.

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Look at the branching ones.

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And when you see this, you know that

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the surrounding lung is well aerated.

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There's no real disease.

3:02

As opposed to this, right?

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It's widespread consolidation.

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There is increasing opacification

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within the parenchyma of the lung.

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This approaches the same density

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of the pulmonary arteries.

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And when it's the same, you can't

3:15

see the pulmonary arteries anymore.

3:17

You don't see that boundary.

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And what you do start to see are things like

3:21

the air bronchograms, because normally we

3:24

don't see the airways, but when the lungs

3:26

become opacified, now we see the airways.

3:29

Okay, we have a reversal.

3:31

So we see things because

3:33

of a difference in density.

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The same is true with CT.

3:37

When you have a good expiration here,

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you can see the branching vessels.

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This is my CT, by the way.

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That's, that's why it's normal.

3:46

When you look at the expiration,

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oh my gosh, we start to lose some air.

3:50

It becomes a little more opaque.

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This is still not enough to obscure the

3:55

vessels, but it is a little bit more opaque.

3:58

And the key here is that on a normal expiration,

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you should get brighter as you go back farther

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where it's more dependent and there's less air.

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Okay.

4:08

So that's, that's normal.

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What determines density are a couple of things.

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One is atomic weight of the, of the, um, organ.

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So lung, which is mostly air, most of

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it gets through and it comes out black.

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Soft tissue like blood, some of it is stopped

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and so it's more gray, and then things like

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bone and metal stop most of the beams,

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and it comes out white on the radiograph.

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So the more dense that particular organ

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is, the more photons it will stop.

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Now, as opposed to the

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other thing is tissue depth.

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So the longer it is, or the more of the

4:44

organ it is, the more it's going to stop.

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So you think of the superior vena cava,

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which is filled with blood, soft tissue density.

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It is vertical with fat and air on both sides.

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But then over on the other side of the

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mediastinum, you have the aortic arch,

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and the aortic arch is horizontal blood.

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It's the same density, but more

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photons have to go through a farther distance,

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so less get through, and as a result,

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on the radiograph, it will appear whiter.

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The tissue densities for

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radiographs are pretty basic.

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It's air, and then fat, water tissue, and metal.

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So when air is next to bone, or air is next to

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water or soft tissue, it will appear whiter.

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They'll be sharp borders.

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Air next to fat, they're a little closer

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together, the borders become a little indistinct.

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On CT, of course, it's much better

5:30

at picking up those differences.

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So differences in density can be used

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even things like for pleural effusions.

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I got taught that fusions were like this veil

5:39

of opacity with hand waving from my faculty.

5:43

Well, let's look at it from

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a different point of view.

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You can see the vessels are nice and sharp here.

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They're a little blurry over here.

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And it's white.

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Here it's white as well, but you

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can't see any of the vessels, and

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you do see little air bronchograms.

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Why the difference?

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Because this tells me that if you can't

6:00

see the vessels, that the surrounding

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lung is abnormal, and that's obscuring the

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vessels, so the problem is in the lung.

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As opposed to here, it's white, but you

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can still see the vessels, which tells

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us there's still air around the vessels,

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so it's probably outside the lung.

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Like the pleura.

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And what that is, is a pleural effusion on the

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right side, but a consolidation on the left.

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So, Imaging Concept 2, what we try to diagnose

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pathology.

6:31

We always try to diagnose a pathology.

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That's what's most important.

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We look at the morphology of the

6:36

abnormality and its distribution.

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Both are important.

6:40

Pathologic process is then suggested, and then

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that is really what's important for the clinician

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as far as prognosis and treatment options.

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Okay.

6:49

Pathology such as this, this is a ground

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glass process in the acute setting.

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This is acute lung injury in a

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setting of acute lung injury.

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The ground glass reflects diffuse

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alveolar damage pathology.

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That's important because the treatment

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for this is very different than say

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treatment of an organizing pneumonia.

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Like this.

7:09

This is a person who's got multifocal

7:11

consolidation, this coronavirus.

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Um, this represents a pathology

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of organizing pneumonia, which is

7:19

different than diffuse alveolar damage.

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Okay, this responds to a

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different form of therapy.

7:28

Now, what we can help with, and what tends to get

7:31

confusing, the etiology that injures the lung.

7:35

It is not the same as pathology.

7:38

The same etiology can cause

7:39

a variety of pathologic.

7:41

If we all took amiodarone, some would

7:44

develop nothing in the lung, others would

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develop UIP, others would develop NSIP,

7:49

others would develop organized pneumonia.

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And when you start to go to

7:53

lectures, or you read books.

7:56

Based on etiology, you walk out thinking

8:00

anything can look like anything.

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And that's where things get confusing.

8:05

So remember people like snowflakes, we react

8:09

different to different etiologic injuries.

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For example, fibrotic NSIP, that's a pathology.

8:17

Okay.

8:17

That's the injury based on the

8:19

morphology and the distribution.

8:21

We think this is fibrotic NSIP that carries

8:24

with it a prognosis and treatment option.

8:27

Now drug toxicity, that's an etiology.

8:30

So if someone says to me, hey, this person

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has drug toxicity, I'm like, well, what is it?

8:36

Is it UIP?

8:37

Is it an NSIP?

8:38

Is it organized pneumonia?

8:39

Is it acute xenophobic pneumonia?

8:41

See, that's where it gets confusing

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and these things get intertwined.

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So there's a lot of them, but I want you to start.

8:51

To reorganize your thought process we diagnose

8:54

pathology. We look at the morphology and we

8:56

try to figure out is it one of these things?

8:59

There's a few other rare ones,

9:00

but these are the more common one.

9:02

Okay, that's what we try to diagnose.

9:07

These are etiologies and these can induce.

9:11

Most of the, of the pathologies so you try

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to think well, what's the most common?

9:17

Etiology for this particular pathology and

9:19

you can list a couple. Uh, but the clinician

9:21

will have to do the workup but you know,

9:23

we can help out here now. How do you use this?

9:28

Well, you look at this. These are three

9:30

different people all with consolidation all

9:34

having an organizing pneumonia pathology.

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So multifocal consolidation

9:39

consistent with organized pneumonia.

9:41

Potential etiologies would include, and this one

9:44

is graft versus host in a BMT patient, cryptogenic

9:48

organized pneumonia, which we don't know what's

9:50

inducing the organized pneumonia response.

9:52

And this one is a coronavirus patient with

9:54

acute lung injury, but with predominantly

9:57

organized pneumonia reaction, which tends to

9:59

have a better response to things like steroids.

10:04

Okay, so organize your reports,

10:07

separate pathology and etiology.

10:09

This is a patient who's got ground glass

10:11

traction bronchial excess to no honeycombing.

10:14

Um, this looks like to me

10:17

a fibrotic NSIP pathology.

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And so my report would be moderately

10:21

advanced pulmonary fibrosis,

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most likely fibrotic NSIP pathology.

10:25

UIP pathology is possible,

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but less likely.

10:29

Consider an autoimmune disease or

10:31

drug toxicity as possible etiologies.

10:34

If tissue sampling is suggested,

10:37

you could do a VAT.

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Now you see how you separate it out,

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it becomes more clear in your mind

10:42

and more clear for the clinician.

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So that is the introduction one.

10:48

Remember, the greater the difference in organ

10:51

border densities, the better you see them.

10:53

Pathology is what is most closely related to

10:56

prognosis and treatment options, and that's what

10:58

we try to diagnose and try to separate pathology

11:02

differential and etiology in your reports.

11:06

With that, I will say thank you for

11:08

listening and move on to introductory

11:11

session two when you're ready.

11:12

Thank you.