Mediastinum, Lymph Nodes, Chest Wall

Question 1

Identify the structure

Answer 1

Normal thymus
“Sail sign”

Question 2

What is a mediastinal shift? What causes it?

Answer 2

Rightward or leftward displacement of mediastinum (including cardiac silhouette) on DV/VD view
Potential causes: volume loss or increase

Question 3

Identify the abnormality

Answer 3

Left-sided mediastinal shift

Question 4

Identify the abnormality

Answer 4

Mediastinal shift

Question 5

What are potential causes of widening of the cranial mediastinum on VD view?

Answer 5

Fat
Masses

Question 6

What is normal width of cranial mediastinum on VD view?

Answer 6

Dogs: <2x the width of thoracic vertebrae
Cats: same size as thoracic vertebrae

Question 7

Answer 7

Mediastinal fat

Question 8

Answer 8

Mediastinal fat

Question 9

Answer 9

Mediastinal fat

Question 10

Answer 10

Mediastinal fat

Question 11

What are the 4 differentials for a cranioventral mediastinal mass?

Answer 11

1. Lymph node enlargement
2. Thymoma
3. Brachial/mediastinal cyst
4. Ectopic thyroid tumor

Question 12

What are radiographic signs of a cranioventral mediastinal mass?

Answer 12

VD/DV usually midline mass
All views: displaced trachea, +/- heart, +/- less cranial lung inflation

Question 13

Answer 13

Cranioventral mediastinal mass

Question 14

Answer 14

Cranioventral mediastinal mass

Question 15

What are radiographic findings of pneumomediastinum?

Answer 15

Large volume of gas = increased visibility of mediastinal structures (trachea, esophagus, major vessels)

Question 16

Answer 16

Pneumomediastinum

Question 17

Answer 17

Pneumomediastinum

Question 18

What are causes of pneumomediastinum?

Answer 18

Tracheal tear/rupture
HBC, bite wound, overinflation of ET rube
Esophageal perforation

Question 19

Where are sternal lymph nodes located?

Answer 19

Just dorsal to the 1st-3rd sternebrae on midline
Usually only seen on lateral view

Question 20

Answer 20

Sternal lymphadenopathy

Question 21

Where are cranial mediastinal lymph nodes located?

Answer 21

Dorsal to region of sternal lymph nodes
Cranial to cardiac silhouette, ventral to trachea

Question 22

Answer 22

Cranial mediastinal lymphadenopathy

Question 23

Answer 23

Cranial mediastinal lymphadenopathy

Question 24

Answer 24

Question 25

Answer 25

Sternal and cranial mediastinal lymphadenopathy

Question 26

Where are tracheobronchial lymph nodes located?

Answer 26

VD/DV: enlarged middle node = mass between mainstem bronchi Lateral: carina may be angled ventrally

Question 27

Answer 27

Tracheobronchial lymphadenopathy

Question 28

Answer 28

Tracheobronchial lymphadenopathy

Question 29

What are differentials for tracheobronchial lymphadenopathy?

Answer 29

Histiocytic sarcoma or lymphoma Fungal disease

Question 30

Answer 30

Histiocytic sarcoma *All thoracic lymph nodes enlarged*

Question 31

Answer 31

Histiocytic sarcoma *All thoracic lymph nodes enlarged*

Question 32

Answer 32

Thoracic lymph node enlargement

Question 33

Compare the appearance of tracheobronchial lymph node ls left atrial enlargement?

Answer 33

Question 34

Answer 34

Normal trachea

Question 35

Answer 35

Normal trachea

Question 36

What are causes of tracheal narrowing?

Answer 36

Tracheal collapse due to chondromalacia *Small breed dogs* Can be static or dynamic

Question 37

Answer 37

Tracheal collapse

Question 38

What radiographic findings are associated with traumatic diaphragmatic hernias?

Answer 38

Can't see part of the diaphragm *Abdominal organs in thorax, soft tissue opaque +/- gas-containing*

Question 39

Answer 39

Diaphragmatic hernia

Question 40

Answer 40

Diaphragmatic hernia

Question 41

Answer 41

Diaphragmatic hernia with pleural fluid (common)

Question 42

Answer 42

Diaphragmatic hernia

Question 43

Answer 43

Diaphragmatic hernia

Question 44

What does a PPDH look like on radiographs?

Answer 44

Large cardiac silhouette Unusual cardiac silhouette contents Cardiac silhouette merges with ventral diaphragm

Question 45

Answer 45

PPDH

Question 46

Answer 46

PPDH

Question 47

Answer 47

PPDH

Question 48

Answer 48

PPDH

Question 49

What does a hiatal hernia look like on radiographs?

Answer 49

Portion of the stomach herniates into the thorax, in expected region of thorax (+/- contained gas) Often intermittent/dynamic (may or may not be seen on radiographs)

Question 50

Answer 50

Hiatal hernia

Question 51

Answer 51

Hiatal hernia

Question 52

Answer 52

Hiatal hernia

Question 53

Answer 53

Hiatal hernia

Question 54

Normal Rib Cage

Answer 54

13 paired ribs Symmetric Evenly spaced

Question 55

Answer 55

Rib tumor

Question 56

Answer 56

Rib tumor

Question 57

What do rib tumors look like on radiographs?

Answer 57

Can be expansile, lytic, or osteoproductive *Look for rib lysis if there is an extrapleural mass* *Can be complete lysis of the rib*

Question 58

Compare the appearance of extrapleural vs pulmonary masses

Answer 58

Question 59

Answer 59

Extrapleural mass

Question 60

Answer 60

Pulmonary mass

Question 61

Answer 61

Rib tumor Red = osteoproduction Yellow = soft tissue mass

Question 62

Answer 62

Rib tumor

Question 63

Answer 63

Rib tumor

Question 64

Answer 64

Acute rib fracture

Question 65

Answer 65

Acute rib fracture with soft tissue swelling and subcutaneous emphysema

Question 66

Answer 66

Healed rib fracture

Question 67

Answer 67

Degenerative sternal change *Common, unimportant*

Question 68

Answer 68

Ill-defined lysis, irregular periosteal proliferation *Neoplasia or osteomyelitis*