Imaging of the Mediastinum, Chest Wall, and Diaphragm

Question 1

What are examples of mediastinal disease?

Answer 1

Mediastinal shift
Pneumomediastinum
Mediastinal mass

Question 2

What is in the mediastinum?

Answer 2

Heart, great vessels, trachea, esophagus, lymph nodes

Question 3

What is the parietal pleura?

Answer 3

Space b

Question 4

What is the pleural cavity?

Question 5

What is the visceral pleura?

Question 6

What is a mediastinal shift?

Answer 6

Occurs as result of unilateral decrease in lung volume (ipsilateral shift) or unilateral increase in lung volume

When you see the heart shift to one side = mediastinal shift
Body won’t let one part collapse, usually heart shift is towards the side that decreased in volume

Ex. Intrathoracic mass or increased intrathoracic pressure resulting in contralateral shift

Seen on VD/DV view

Question 7

What is one of the reasons the heart can shift to the left side on VD/DV view?

Answer 7

Prolonged left lateral recumbency

Question 8

What is pneumomediastinum?

Answer 8

Air has entered the mediastinal space
May be able to see Azygous vein and cranial vena cava

Question 9

What are causes of pneumomediastinum?

Answer 9

Tracheal rupture
Esophageal rupture
Cervical soft tissue injury
SQ emphysema
Lung trauma (hit by car)

Question 10

What do mediastinal masses do?

Answer 10

Occur in midline location
Lead to displacement of mediastinal structures
May involve cranial, middle, and caudal mediastinum

Question 11

What is the most common location for mediastinal masses?

Answer 11

Cranial

Question 12

Mediastinal cyst

Question 13

Where are the sternal lymph nodes?

Answer 13

Ventral mediastinum, 2nd intercostal space

Question 14

What do the sternal lymph nodes drain?

Answer 14

Drain the peritoneal cavity
If enlarged at look at the abdomen

Question 15

Where are the cranial mediastinal lymph nodes?

Answer 15

Lie along cranial vena cava, ventral to trachea (just below trachea)

Question 16

Where are the tracheobronchial (hilar) lymph nodes?

Answer 16

Middle mediastinum, surround stem bronchi and carina
Sit right on top of the heart, right on top of the right atrium

Question 17

Where do the tracheobronchial lymph nodes drain?

Answer 17

They drain the lungs

Question 18

How can you tell between a left atrial enlargement and tracheobronchial (hilar) lymphadenopathy?

Answer 18

THL corina deviates ventrally
LLE pushes corina dorsally

Question 19

Tracheobronchial (hilar) lymphadenopathy

Answer 19

Creates a mass effect right at the corina

Question 20

What diagnosis can be made when all 3 lymph nodes are enlarged?

Answer 20

Lymphoma

Question 21

What makes up the chest wall?

Answer 21

Skin, fat, muscle, parietal pleura, spine, sternum, and ribs

Question 22

Superimposed skin artifacts, fat, or ticks can appear like what?

Answer 22

Pulmonary nodules

Question 23

What do skin folds look like?

Question 24

How does the CCJ vary with age in dogs?

Answer 24

In older dogs, it can be seen but it is mineralized and be very proliferative (mistaken for nodules on VD/DV)
In puppies it can’t really be seen

Question 25

Describe an extrapleural mass

Answer 25

Well circumscribed, with convex margin towards lung. Cranial and caudal margins taper, creating broad-based mass
Located in thoracic wall, usually of rib origin
Commonly cause pleural effusion

Question 26

How can you tell you are looking at a left lateral?

Answer 26

Left crus is forward, right crus is back, caudal vena cava is at the intersection between the two crua, translucent structure between the two crua is the stomach (fundus)

Question 27

How can you tell you are looking at a right lateral?

Answer 27

Right crus is forward, left crus is back, caudal vena cava going directly into right crus. The two crua don’t intersect, they run parallel to each other.

Question 28

If you are on a left lateral what lung lobes are you looking at? What about right lateral?

Answer 28

Right lung lobes, the down lung is collapsed so less contrast. Right lateral you would be looking at the left lungs. This doesn’t work in small dogs and cats.

Question 29

Which view has 3 humps where you can see the right and left crus and the cupula?

Answer 29

VD - ventral dorsal

Question 30

Which view has one hump and is better for seeing caudal lung lobes?

Answer 30

DV - dorsal ventral

Question 31

Diaphragmatic hernia

Answer 31

Cranial displacement of abdominal viscera, loss of normal diaphragm
Ex. traumatic hernia -> acute (hit by car) or chronic (small intestine herinated)

Question 32

What are the 3 types of lung patterns?

Answer 32

Alveolar, interstitial, and bronchial patterns

Question 33

What is a lung pattern?

Answer 33

Increased pulmonary opacity that corresponds to a particular component of the lung

Question 34

What are components of the parenchyma?

Answer 34

Alveoli = air-filled sacs
Bronchial walls = airways
Interstitial tissue = framework of the lungs
Pulmonary vessels = creates most of the normal background opacity

Question 35

What happens with bronchitis?

Answer 35

Thickened walls and coughing

Question 36

Should alveoli and bronchi contribute to the background opacity?

Answer 36

No because they are air filled

Question 37

What creates most of the normal background opacity?

Answer 37

Arterties and veins

Question 38

What does pulmonary disease usually result in?

Answer 38

Increased lung opacity