Trachea and Mediastinum

Question 1

Normal position of trachea - should diverge from the spine by what angle? Exceptions with brachiocephlic and deep chested breeds?

Answer 1

15-30 degrees; barchiocephalic breeds less; deep chested breeds more

Question 2

Carina should be placed posterior to rib #__

Answer 2

5

Question 3

Trachea is normally runs right on the midline on the VD view, however in brachiocephalic breeds, it may right slightly to the ____ of the midline.

Answer 3

right

Question 4

Dorsal displacement of trachea

Answer 4

1. Cranioventral mediastinal mass - LN, thymus, tumor (lymphoma), abscess
2. Heart enlargement or heart base tumor

Question 5

Ventral displacement of trachea

Answer 5

1. Megaesophagus - MC, vascular ring anomaly, foreign body

2. Dorsal mediastinal mass

Question 6

Lateral tracheal displacement

Answer 6

1. Cranial mediastinal mass, pulmonary mass
2. Mediastinal shift/atelectasis
3. Positional artifact - due to rotation of the dog

Question 7

Caudal tracheal displacement

Answer 7

Cranial mediastinal mass

Question 8

The most common vascular ring anomaly in puppies is:

Answer 8

Persistent 4th right aortic arch

Question 9

Persistent 4th left aortic arch is abnormal or normal?

Answer 9

Normal

Question 10

Normal tracheal size

Answer 10

Diameter of the lumen should be ~3xs the width of the 3rd rib; or 1/5 (20%) height of thoracic inlet; brachiocephalic dogs can have tracheal lumen be as low as 16% of the thoracic inlet

Question 11

Ddx for small trachea

Answer 11

1. Hypoplasia - congenital - MC, brachycephalic breeds
2. Stenosis - trauma, congenital
3. Intrathoracic tracheal collapse
4. Compression by extralumenal mass

Question 12

With an intrathoracic tracheal collapse, radiographs should be taken on ______, because the trachea will decrease in size, and illustrate the tracheal collapse.

Answer 12

Expiration

Question 13

Ddx for large trachea

Answer 13

Upper respiratory obstruction

Question 14

Is mineralization of the tracheal lumen normal?

Answer 14

Yes, it will mineralize with age

Question 15

Tracheal rupture or puncture will most likely cause a pneumo____

Answer 15

pneumomediastinum

Question 16

Three tumors in the tracheal lumen:

Answer 16

Chondroma, Osteosarcoma, and Squamous cell carcinoma

Question 17

Redundant Dorsal Trachealis Membrane

Answer 17

You can still see the dorsal surface of the trachea (not a collapse), but the dorsal membrane falls, creating a flap that obstructs airflow

Question 18

Mediastinum

Answer 18

Compartment of the thoracic cavity between the medial aspects of the two pleural sacs;
Cranial (precardiac), Middle (pericardiac), caudal (postcardiac)

Question 19

Mediastinum opens -

Answer 19

Cranially and caudally

Question 20

Unilateral penumothorax/pleural effusions are common. True or False.

Answer 20

False. They are RARE due to mediastinal communication

Question 21

Mediastinal structures normally seen:

Answer 21

Trachea, heart, aorta, caudal vena cava, carniomediastinal reflection, caudomediastinal reflection, thymus in young animals

Question 22

The cranioventral mediastinal reflection is best seen on which views

Answer 22

Lateral

Question 23

The caudoventral mediastinal reflection is ONLY seen on which views?

Answer 23

VD/DV

Question 24

Mediastinal structures NOT normally seen

Answer 24

Cranial vena cava, brachiocephalic trunk, left subclavian artery, azygous vein, LNs (sternal/retrosternal, hilar/tracheobronchial, cranial mediastinal); esophagus - unless it contains gas or fluid/mass

Question 25

Where can the thymus be seen in young animals (up to 4-6 months of age)?

Answer 25

Within the cranioventral mediastinal reflection

Question 26

Clinical signs of mediastinal abnormalities:

Answer 26

Dyspnea, dysphagia (trouble swallowing) and/or regurgitation, cardiovascular disturbances (signs of right heart enlargement: forelimb edema, ascites, hepatomegaly)

Question 27

Ddx to mediastinal shift

Answer 27

1. Atelectasis - loss of lung volume 2. Diaphragmatic hernia 3. Adhesions 4. Unilateral pneumothorax or pleural effusion (pyothorax) 5. Technical artifact - poor VD positioning

Question 28

Radiographic signs of pneumomediastinum:

Answer 28

Increase in radiolucency, so structures not normally seen are visible; on lateral view you see tracheal stripe sign

Question 29

Tracheal stripe sign is indicative of:

Answer 29

pneumomediastinum; occasionally air in megaesophagus can highlight trachea and create a tracheal stripe sign

Question 30

Vessels seen of of the cranial vena cava is a definitive sign of:

Answer 30

Pneumomediastinum

Question 31

Causes of pneumomediastinum:

Answer 31

1. Soft tissue wound - neck, axilla, venipuncture 2. Tracheal rupture (trauma, venipuncture, over-inflated tracheal cuff, transtracheal wash) 3. Bronchial rupture 4. Alveolar rupture 5. Esophageal perforation 5. Gas producing organisms (rare)

Question 32

Three complications of pneumomediastinum:

Answer 32

1. Pneumothorax 2. Pneumoretroperitoneum 3. Mediastinitis

Question 33

Treatment of pneumomediastinum:

Answer 33

Self-limiting if no complications - air resorbed in 7-10 days; remove gas if secondary pneumothorax present and animal is dyspneic

Question 34

Normal mediastinum should be no wider than __x the width of the thoracic vertebrae on the VD view.

Answer 34

2x

Question 35

MC cause of widening of mediastinum with NO mass:

Answer 35

Fat

Question 36

Causes of mediastinal widening:

Answer 36

Fat - evenly distributed, lymphadenopathy, mediastinitis, hemorrhage, abscess, edema

Question 37

Causes of cranioventral mediastinal masses:

Answer 37

1. Fat (lipoma) 2. Thymus (thymoma) 3. Thyroid (thyroid adenocarcinoma) 4. Mediastinal lymph nodes (lymphosarcoma) 5. Retrosternal lymph nodes 6. Abscess

Question 38

Differentials to cranioventral mediastinal mass:

Answer 38

1. Pleural effusion | 2. Pleural, pulmonary, and thoracic masses

Question 39

Radiographic signs of cranioventral mediastinal masses:

Answer 39

1. Dorsal +/- lateral deviation of trachea 2. Increased opacity of mediastinum cranial to heart 3. Silhouette with heart 4. Carina displaced caudally 5. +/- esophageal air accumulation

Question 40

Causes of craniodorsal mediastinal masses

Answer 40

Esophagus MC - (megaesophagus, esophageal foreign body); trachea; cranial vena cava; aortic arch, nerves

Question 41

Radiographic signs of craniodorsal mediastinal mass:

Answer 41

ventral dispalcement of trachea; distended esophagus

Question 42

Causes of perihilar mediastinal masses:

Answer 42

Tracheobronchial lymph nodes, pulmonary vessels, left and right atria, esophagus

Question 43

Radiographic signs of perihilar mediastinal masses:

Answer 43

Increased opacity, displacement of tracheal bifurcation, constriction of trachea

Question 44

Radiographic appearance of HW disease

Answer 44

Torturous pulmonary arteries that stand out in the caudal lung lobes!

Question 45

Causes of dorsocaudal mediastinal masses

Answer 45

Caudal esophagus (granuloma, hiatal hernia, epiphrenic diverticulum, spirocerca lupi), diaphragmatic hernia, descending aorta, nerves

Question 46

Radiographic signs of dorsocaudal mediastinal mass:

Answer 46

Increased opacity dorsocaudal thorax on lateral; increased opacity midline on VD and DV

Question 47

Causes of caudoventral mediastinal mases:

Answer 47

Pericardial cyst, peritoneopericardial or other diaphragmatic hernia, abscess or granuloma

Question 48

Radiographic signs of caudoventral mediastinal mass:

Answer 48

Silhouette with the heart, increase opacity at midline on VD and DV