0:01

Okay, well, welcome here.

0:02

Cardiopulmonary Mastery Series.

0:04

We're going to keep going

0:05

with the lateral radiograph.

0:08

And the lateral radiograph, uh, it kind

0:11

of intimidates a lot of radiologists,

0:13

so we'll break it down and try and

0:15

make it pretty easy here if we can.

0:17

We're going to go through quickly just a little

0:19

basic anatomy on the lateral and then learn

0:21

about some pathologic processes that are actually

0:24

better seen on the lateral than on the PA.

0:27

And hopefully try to incorporate some sort of

0:30

practical search pattern when you're presented

0:32

with one of these lateral radiographs.

0:35

So anatomically, it's set up where you've got

0:38

the heart anteriorly, and you can actually see

0:41

the three of the chambers really well, the right

0:44

ventricle, which sits right behind the sternum,

0:46

The left ventricle, which you see a little bit

0:48

of the behind and up above it is the left atrium.

0:52

Remember, the left atrium is actually

0:54

above the left ventricle, not behind it.

0:57

That's kind of how it's always

0:58

shown, but it's above it.

1:00

And then the other thing I want to show

1:01

you is when you look at this, you want to

1:04

identify the arch and the left main bronchus.

1:07

And I'll show you why the left main bronchus

1:09

on end, that's going to be really important.

1:12

And then the trachea.

1:13

Okay, so let me take you through it.

1:16

I've highlighted some areas that I would

1:20

like you to try to incorporate in your

1:22

search pattern for the lateral radiograph.

1:24

It is really amazing to find pleural

1:28

effusions because that's the basement.

1:30

The costophrenic angles in

1:31

the PA is the first floor.

1:33

You got to flood the basement back here

1:35

before it spills over so looking for

1:38

any blunting here enlarged hilar

1:40

nodes I'll show you how to do that.

1:42

This is really this is so much easier than

1:45

the PA. Uh, low bar consolidation, lower lobe

1:48

consolidation, you go down the vertebral bodies.

1:50

They should get darker because you got more lung.

1:53

Well, if you got a whiteness here,

1:54

if that's interrupted, you have

1:56

to have an explanation for that.

1:59

Right ventricular enlargement, it sits right

2:01

behind the sternum, one third of the, uh,

2:03

one quarter to one third of the way up.

2:05

As it dilates or hypertrophies, it

2:07

crawls up into that retrosternal space.

2:10

Uh, left ventricular will be right here.

2:13

This is the left ventricle.

2:14

There's your inferior vena cava.

2:16

As it tends to dilate, it starts to sag backwards

2:19

greater than two centimeters behind the sternum.

2:22

IVC and the left atrium which is just above

2:25

it will pooch out and when it's enlarged,

2:28

Um, pericardial effusion, the so-called oreo

2:31

sign. You look right here in the retrosternal

2:33

area. You look at and you can find these

2:35

pericardial effusions, the retrosternal fat

2:38

and the epicardial fat. What's in between

2:40

it shouldn't be more than four millimeters.

2:43

And the last one you may not have been

2:44

taught about is the so-called retrotracheal

2:47

triangle right here above the arch in front

2:50

of the vertebral body behind the trachea.

2:52

There should be absolutely nothing in here.

2:55

Nothing in here.

2:56

This was described by Louis Rader.

2:59

It's called Rader's triangle, but you

3:01

know, retrotracheal triangle, if you wish.

3:03

So, looking here.

3:05

Perception.

3:06

This person has a cough.

3:07

Well, there might be something here.

3:09

I think there is.

3:10

It's ill-defined.

3:11

There's some air bronchograms.

3:12

I don't see the vessels very well.

3:14

But when you look back here,

3:15

you say, "Oh, there it is."

3:17

You go down the vertebral bodies.

3:19

They're not getting darker here.

3:20

They're whiter at this level.

3:22

This is a left lower lobe consolidated pneumonia.

3:25

Again, the lateral projection, very

3:28

helpful when you have your search pattern.

3:32

The search pattern is going down the

3:34

vertebral body and taking a look behind

3:36

the heart, behind the heart as well.

3:39

And um, this is a nice area where you

3:41

can pick up a lot of pneumonias that may

3:43

be behind the diaphragm or behind the

3:46

heart and not so conspicuous on the PA.

3:50

This is Raider's triangle or

3:52

the retrotracheal triangle.

3:53

There should be absolutely nothing in here.

3:55

So when you see something like this, okay.

3:58

That's not normal.

4:00

That needs an explanation.

4:01

In this case, this is a, uh, large aberrant

4:04

right subclavian artery with a ductus

4:07

of comoral aneurysm, and it's filling

4:09

in that retrosternal triangle, and it's

4:12

even deviating the trachea anteriorly.

4:14

If you see any nodule, overlying this.

4:17

That needs an explanation.

4:19

It might be sitting right behind the

4:20

clavicle in the PA and not conspicuous.

4:22

Patient with achalasia.

4:26

Well, it's kind of subtle here.

4:27

There's a subtle air-fluid

4:28

level, but boy, not subtle here.

4:30

That retrosternal, um, sorry, that

4:33

retrotracheal, um, triangle is completely filled.

4:37

And so again, part of your search pattern.

4:40

And then let's get to the hilum.

4:42

The hilum is a lot easier, I think, on the lateral

4:46

when it's enlarged lymph nodes than the PA.

4:48

You see, the left main bronchus comes about

4:50

perpendicular, and then this is it on, uh,

4:53

on end, and that's what it is right here.

4:56

This central lucency is seen

4:58

about 95 percent of the time.

5:00

That's your starting point.

5:02

That's central lucency.

5:03

Identify it on every lateral.

5:06

From there, the right pulmonary artery,

5:08

which is seen on end, over here, is actually

5:13

represented by this oblong white area.

5:16

So it kind of looks like they're

5:17

next to each other, but they're not.

5:20

That's normal, lucency, white, kind of

5:24

oblong, circular region, pulmonary artery.

5:28

This is not normal.

5:29

There is your central lucency, and when you

5:31

have that right pulmonary artery opacity

5:33

that goes all the way around it, like

5:36

a donut or a bagel, that is adenopathy.

5:41

That's adenopathy.

5:43

This is what it looks like normally.

5:45

There's your right pulmonary artery.

5:47

Same patient and it's that's a donut, that's

5:52

adenopathy, and it's even mild adenopathy

5:55

will pick up on the lateral as long as

5:57

you know what to look for and where to

5:59

start, left main bronchus lucency.

6:02

Is there white all the way around it?

6:04

There is adenopathy.

6:05

Pleural effusions, the lateral costophrenic angle,

6:09

this is where you get taught, is there blunting?

6:11

Well, this takes about, you know, cc's

6:16

to blunt, but this one can 30 to 50

6:18

cc's and you start seeing it already.

6:21

So pleural effusion will flood the posterior

6:23

basement costophrenic angle on the lateral

6:26

projection before it manifests on the PA.

6:31

Okay.

6:32

Patient does have some blunting bilaterally,

6:34

but you can see it very easily here.

6:36

This is layering and quite

6:37

simple, bilateral small effusions.

6:41

This patient has a fairly large

6:43

effusion, but look at the PA.

6:45

It's really hard to see it.

6:47

It's there, but it's much larger and you can

6:51

really quantify it much better on the lateral.

6:53

The other thing is that it's probably passive

6:56

atelectasis in that right lower lobe.

6:58

But what if they have a little fever?

7:00

Well, you can tip them down.

7:02

And so decubitus fuses are often taught, but

7:05

most people do decubitus ruses incorrectly.

7:08

They tip the same side as the effusion down.

7:12

Why would you do that?

7:13

Tip the opposite side down.

7:16

So this is the same patient is here.

7:19

With this questionable opacity is

7:20

that atelectasis or consolidation.

7:23

We tip the person down onto their opposite

7:25

side middle left side, and that hyperinflates

7:28

the right lung, and look, it disappeared.

7:32

And we know the fluid is mobile because it's not

7:35

there, it's all right along the mediastinum.

7:38

So it's a layering of fusion

7:39

with atelectasis in the right lower lobe.

7:44

This patient did bilateral decubitus.

7:48

This is the same side down as the effusion,

7:51

and it's just a minimal effusion, but

7:52

you can't read anything else here.

7:54

But when we tip the person down on

7:56

the right side, the consolidation

7:59

within the left lower lobe manifested.

8:02

So if it was atelectasis, it should pop open.

8:05

If it doesn't, that's probably

8:07

a consolidated pneumonia.

8:09

And the effusion is a little

8:10

reactive or paramagnetic effusion.

8:13

Okay.

8:14

Then the cardiac chambers, right

8:17

ventricular enlargement, it will crawl up.

8:20

Left atrial gives you a little

8:22

bump here and the left ventricle.

8:24

This is normal.

8:25

There's your inferior vena cava.

8:26

So this is mitral stenosis.

8:28

with pulmonary hypertension

8:29

and right heart enlargement.

8:31

This is a patient who's got the left

8:33

atrium as dilated and the left ventricle.

8:35

Look, it's actually extended back to the spine.

8:38

That's not normal.

8:39

So both the left atrium and the

8:41

left ventricle are both dilated.

8:42

So chambers of the heart best

8:45

evaluated on the lateral.

8:46

What else can be?

8:48

Well, this can be, this is the epidural fat.

8:51

This is the retrosternal fat.

8:53

That's more than four millimeters.

8:54

That's a pericardial effusion.

8:57

By the way, the echo done before

8:58

this said there was no fusion.

9:01

Yes, there is.

9:02

Yes, there is.

9:03

And you will miss this unless this

9:06

is part of your search pattern.

9:08

You look in the area of the heart anteriorly.

9:11

Do you see something that looks like an Oreo?

9:13

So, the lateral radiograph, extraordinarily

9:16

helpful, especially with pleural effusions.

9:18

Hilar adenopathy is excellent.

9:21

Cardiac chambers, except the right atrium.

9:24

Pericardial effusion.

9:26

And lower lobe consolidation around atelectasis.

9:28

And remember to always check

9:30

the retrosternal triangle.

9:31

There should be nothing in it.

9:33

Try to incorporate these regions in

9:35

your search pattern with the lateral

9:37

radiograph and see what you turn out.

9:40

Thank you.