0:01

I think it's important to understand anatomic landmarks while you're looking

0:05

at imaging. And so I don't want to assume that people know

0:11

landmarks, or this is their first time, that they haven't seen an x

0:13

ray of the chest, but certainly as you're beginning

0:17

work in this area, the chest x ray is going to be something

0:20

very common. The PA and the lateral view.

0:24

This is the PA view or the frontal view. And I will just

0:27

point out some very basic anatomy for those who may just need an

0:31

introduction. Again, the black parts here are the lung fields.

0:35

We're going to look at the heart, which is outlined here in the. We usually

0:39

refer to that as the cardiac silhouette because in here we're seeing not

0:44

just the heart itself, but there's pericardium. We're not appreciating,

0:48

but there are vessels in here that are moving from the hilum that

0:53

are originating from the heart that we also want to account for.

0:57

Things like this subtle shadow along here, which is the aorta,

1:02

which you don't see very well but it's also contained within this space.

1:05

You have to account for those. And so terminology like mediastinal contours

1:11

or cardiomediastinal contours or silhouettes encompass this entire area.

1:16

These areas here are pulmonary vessels that are branching and the hilar

1:20

area is right here in this almost the armpit and then everything kind

1:24

of sprouts from there. We're looking at ribs and just in terms of

1:28

orientation, these are the posterior ribs, which are going to be a little

1:33

bit more horizontally oriented. Then you're going to have anterior ribs,

1:37

which are a little bit more vertically oriented.

1:40

The lateral portions of the ribs are going to be along here.

1:45

Again, on the right side, the lateral portions, we've got the more vertically

1:50

oriented anterior ribs and the more horizontally posterior ribs. If you're

1:55

counting ribs, trying to understand where you are, this is the first rib

1:58

right here, the second rib right here, the third rib

2:04

and so on. So one, two, three, four, five, six and then you

2:08

keep counting down and normally you'll have 12.

2:11

Included in the field of view for other osseous structures, you're going

2:14

to see the clavicles. Make sure that you're looking at those each and

2:17

every time. Take a look at the scapula, take a look at the

2:20

glenohumeral joint, look at the humerus. You may see varying portions of

2:25

those depending what's included in the field of view. You're going to get

2:28

a little bit of cervical spine up in here. You want to make

2:31

sure that you're looking at the thoracic spine. Sometimes if you are able

2:35

to window and level, you can begin to see the bones a lot

2:39

more clearly but you want to look at the vertebral body heights.

2:42

You want to see if you can assess the disc spaces.

2:44

You want to look at the paravertebral soft tissues

2:48

to make sure that there's not any hematoma, that there's not any evidence

2:52

of injury. Take a look underneath the diaphragm,

2:57

so the abdominal contents. You want to look for, on the upright view,

3:00

any evidence of free gas. You will see gas here which is a

3:04

normal expected location for the gastric bubble. So the stomach is going

3:10

to contain a little bit of air oftentimes and it will appear here.

3:13

So that's not anything to worry about. Don't forget to look at your

3:17

lateral view. And so why I like the lateral view or why I

3:20

think it's very helpful is it helps to

3:23

triangulate things that you might be seeing on the frontal, the AP or

3:27

the PA view. You will take a look at the

3:30

thoracic spine, its alignment, the body heights. Nice to see, be able to

3:34

follow here. Again, you're going to see some of the lateral ribs that

3:37

are kind of displayed out here for you.

3:40

You want to take a look at the cardiac contour, the retrocardiac space

3:43

here. There should be some vessels that are flowing along here.

3:46

So these are the vessels that we saw coming out of the hilum. This

3:50

is the heart along here. If we window down,

3:55

we're going to see bony structures. So the manubrium and the sternum.

3:58

This is important to check out particularly for patients who are having

4:02

pain, trauma, sternal fractures, sternal hematomas. You will appreciate

4:07

those if you're looking for them. Look for some degree of retro sternal

4:11

clear space. When that fills in patients who have masses in the anterior

4:16

mediastinum, this is something that you want to be able to check and

4:20

see if that area is still clear. Again, if you look below the

4:23

diaphragm, you'll see the gastric bubble. But if you're also looking for

4:28

areas of free gas, this is kind of again a helpful place for

4:32

you to look. So again, here are some general structures that you're going

4:35

to see on the AP and lateral. Don't forget to just take a

4:39

look at the soft tissues. So again, looking for foreign bodies,

4:42

patients who have lacerations, subcutaneous emphysema. These are things

4:47

that you'll find if you look in the soft tissues.

4:50

And this is essentially a normal examination, but what I've tried to do

4:53

is demonstrate some of the major areas of interest and things that you

4:58

might have people referring to. Again, a couple of places to keep in

5:02

mind when you're looking for things like pleural effusions. For a patient

5:05

who's got a simple pleural effusion and who is standing upright for a

5:10

PA examination, those should actually be dependent. So they're going to

5:14

fall here to the costophrenic angles and those will begin to blunt,

5:18

but these are normal. If we're looking at pneumothoraces, gas air is going

5:22

to rise and so you might see small pneumothoraces begin to appear at

5:27

the apices. So that's the areas up here along the apical lateral spaces

5:32

as well. So when you look at the lateral, the apex is hard

5:36

to see because the shoulders are generally here, but you have the posterior

5:40

costophrenic angles as well as the anterior costophrenic angles. Just keep

5:45

in mind you want to look at both of those. And then this

5:47

is a nice reminder that if you remember from anatomy class that the

5:52

diaphragm is actually not just a flat muscle, it's kind of a cup

5:56

shaped. And so when you're looking sometimes on the frontal view,

6:00

recognize that you might see the diaphragm as this structure right here,

6:04

but in reality the diaphragm is diving posteriorly. And so if you follow

6:08

some of these lung markings right along here, for example, some of those

6:11

lung markings actually extend below what looks like the diaphragm. I'm going

6:16

to blow this up so that we can see it a little bit

6:17

better. So if you look at this, if you think that this is

6:21

just the diaphragm, this is the anterior diaphragm, but in reality there's

6:25

diaphragm that's rolling back and through in here. So this vessel actually

6:29

that's branching that we're seeing faintly, this is part of lung that's

6:34

back here. So this is not just the only part of the diaphragm.

6:38

You're just not seeing it. Don't forget about the posterior portion,

6:41

not just the anterior portion. So there's some pearls on the x ray

6:46

to consider if you're starting things out. For many of you who've seen

6:49

this for a while, this will be a basic review. But let me

6:51

also now go to CT and we'll do something very similar.

6:55

So again, when you're looking at CT from an anatomy perspective,

6:58

I would just say get in the habit of always looking at your

7:01

scout. There's going to be information that's there. And some of the same

7:04

structures that we pointed out on the x ray are going to be

7:07

the same structures that you're seeing on the scout.

7:10

So again, we're seeing the bones, the soft tissues, the heart,

7:14

the lungs, the airway below the diaphragm we're going to see.

7:18

What I'll do is just I'm going to take us pretty quickly through

7:22

the axial, coronal, and sagittal images and just point out a few anatomic

7:28

structures for those who may not necessarily be familiar with them and this

7:31

is your first time looking at a CT.

7:34

Again, just anatomically speaking, we've got the thyroid gland right here.

7:37

There's going to be two lobes. And scrolling down, the isthmus is here

7:41

connecting the two lobes. That's the appearance of the thyroid gland.

7:46

Whether you give contrast or not, it's got a lot of iodinated material

7:50

within it. That's part of how it operates. And it's going to have

7:53

higher attenuation. And so that should not be surprising to you.

7:58

As you're moving down into the and through the thoracic inlet,

8:01

you're going to see, depending on whether you've given contrast or not,

8:05

vascular structures, the gray vessels that are coming in.

8:08

This person has gotten an injection and this is the contrast bolus that's

8:11

moving through the innominate vein and coming down

8:16

and joining through the SVC and into the

8:20

right atrium. If we window down a little bit more,

8:26

it's hard to see the valve but this is the right ventricle.

8:32

Similarly, this is the left ventricle here and here is the left atrium.

8:38

Obviously arising from the left ventricle, we have the aorta

8:43

which is here centrally. The aortic arch is coming around and through here.

8:48

You can follow the aorta down through the diaphragm

8:53

and all the way down. You'll have pulmonary

8:57

vessels. Right now, we see a lot of the contrast that's seen within

9:01

the pulmonary artery. It's going to branch from the main pulmonary artery

9:07

to the right and the left main. On the left, you'll have and

9:10

give rise to the upper lobe and the lower lobe.

9:13

On the right side, you'll give rise to the upper lobe.

9:17

Then you'll have the takeoff for the middle and the lower lobes.

9:21

They're going to continue to arborize and perfuse. What we're seeing a lot

9:25

of here are just the perfused pulmonary arterial tree as it's branching

9:30

throughout. As you're moving through, again, we can take a look at the

9:33

airway. This is the trachea right along here. You can change wind to windows

9:38

that make it a little bit easier to follow

9:43

and we're getting to the carina where it's splitting

9:46

and then it moves into the branching system.

9:51

Other things to appreciate on the axial images

9:55

on a chest CT are the soft tissues. Again, pectoralis major muscles,

9:59

pectoralis minor along here. Within the axillary region, you're going to

10:05

see small lymph nodes but be on the lookout for larger lymph nodes that

10:09

may be reactive. As you move below the diaphragm on chest CT, you're

10:13

going to generally see a portion of the liver here.

10:17

You may get more of it, less of it depending on how much

10:21

is included in the field of view. You may get gallbladder.

10:23

Well, you've got the right adrenal gland right here.

10:30

The left adrenal gland is partially seen right here. The top of the

10:34

kidneys are coming in. You have the IVC. It's going to move through

10:39

the liver. It's hard to see here 'cause it's kind of lost a bit of contrast.

10:44

That's going to also join into the right atrium.

10:50

Other structures below the diaphragm, spleen, stomach. We have a portion

10:55

of the pancreas here as well. Get familiar with those structures because

11:00

you're going to want to look at them. If you're seeing something that's

11:02

a little concerning, you might recommend a dedicated

11:06

CT of the abdomen for further evaluation. We will take a look at

11:10

the lung windows here. I'll point out a few things that I think

11:13

are better demonstrated on the coronal. Let's just put it on lung windows.

11:20

Oftentimes we talk about lung zones versus actual lobes.

11:25

Lung zones I think is much more appropriate when you are looking at

11:28

a radiograph and it may be just a portable radiograph. You're not really

11:31

sure where it localizes. You're not sure if you're anterior or posterior,

11:35

which may put you in the upper lung zone or the lower lung

11:38

zone. But on the CT you're actually able to know really well.

11:43

This line right here and this line right here, these are the major

11:47

fissures. This more horizontal line here is the horizontal fissure or the

11:54

minor fissure. You're able to see those really nicely on CT.

11:57

Get in the habit of identifying those, then when you need them,

12:01

they'll be there for you. On lung windows you can see nicely the

12:04

trachea. You can see a branching at the carina.

12:08

You can see the upper lobe vessels here, the lower lobe vessels here.

12:13

You get a sense of how they continue to branch, which is what

12:15

you'd expect. They get smaller as they arborize. Finally, let's take a look

12:21

at the sagittal. I like this view particularly looking at

12:27

longer structures, so looking at the aorta, looking at the spine.

12:32

Why don't we start with soft tissues. This patient didn't get contrast that's

12:37

optimized for the aorta, but you can see really nicely how the aorta is

12:41

laid out for you. This is a nice view for that.

12:44

There's a lot of streak artifact from the bolus contrast, but

12:49

you can also just follow... It's really like that candy cane view of

12:52

the aorta where you're looking at the great vessels, the takeoffs. Some

12:56

of those you're seeing here, but they're hard to see through the streak

12:58

artifact. It's a nice way to look at the aorta. It's a nice

13:02

way to look at the chambers of the heart.

13:06

Then I really like it for just its

13:09

outlay of looking at ribs on block, and definitely for the orientation of

13:17

the spine, the alignment, the heights of the vertebral bodies,

13:22

the disc spaces. Here you can see, for example, there's a little bit

13:25

of a vacuum disc here. You can check it out for

13:30

degenerative changes, evidence of spondylosis, any sort of malalignment

13:33

that's taking place with the facets. Look at the spinous processes.

13:38

Anteriorly, again, looking at the bony structures, the manubrium and the

13:42

sternum. These are structures that you want to get in the habit of

13:46

looking for, particularly when they're normal, so that when you see something

13:49

that's abnormal, you're able to identify that really well.

13:53

What I've tried to do in this section is really just to provide

13:56

you with, again, a very basic introduction for anatomy that you're going

14:00

to see and should get familiar with on both chest, X ray,

14:04

PA, and lateral, and on CT.