Imaging of the Mediastinum, Chest Wall, and Diaphragm Flashcards
What are examples of mediastinal disease?
Mediastinal shift
Pneumomediastinum
Mediastinal mass
What is in the mediastinum?
Heart, great vessels, trachea, esophagus, lymph nodes
What is the parietal pleura?
Space b
What is the pleural cavity?
What is the visceral pleura?
What is a mediastinal shift?
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
What is one of the reasons the heart can shift to the left side on VD/DV view?
Prolonged left lateral recumbency
What is pneumomediastinum?
Air has entered the mediastinal space
May be able to see Azygous vein and cranial vena cava
What are causes of pneumomediastinum?
Tracheal rupture
Esophageal rupture
Cervical soft tissue injury
SQ emphysema
Lung trauma (hit by car)
What do mediastinal masses do?
Occur in midline location
Lead to displacement of mediastinal structures
May involve cranial, middle, and caudal mediastinum
What is the most common location for mediastinal masses?
Cranial
Mediastinal cyst
Where are the sternal lymph nodes?
Ventral mediastinum, 2nd intercostal space
What do the sternal lymph nodes drain?
Drain the peritoneal cavity
If enlarged at look at the abdomen
Where are the cranial mediastinal lymph nodes?
Lie along cranial vena cava, ventral to trachea (just below trachea)
Where are the tracheobronchial (hilar) lymph nodes?
Middle mediastinum, surround stem bronchi and carina
Sit right on top of the heart, right on top of the right atrium
Where do the tracheobronchial lymph nodes drain?
They drain the lungs
How can you tell between a left atrial enlargement and tracheobronchial (hilar) lymphadenopathy?
THL corina deviates ventrally
LLE pushes corina dorsally
Tracheobronchial (hilar) lymphadenopathy
Creates a mass effect right at the corina
What diagnosis can be made when all 3 lymph nodes are enlarged?
Lymphoma
What makes up the chest wall?
Skin, fat, muscle, parietal pleura, spine, sternum, and ribs
Superimposed skin artifacts, fat, or ticks can appear like what?
Pulmonary nodules
What do skin folds look like?
How does the CCJ vary with age in dogs?
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
Describe an extrapleural mass
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
How can you tell you are looking at a left lateral?
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)
How can you tell you are looking at a right lateral?
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.
If you are on a left lateral what lung lobes are you looking at? What about right lateral?
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.
Which view has 3 humps where you can see the right and left crus and the cupula?
VD - ventral dorsal
Which view has one hump and is better for seeing caudal lung lobes?
DV - dorsal ventral
Diaphragmatic hernia
Cranial displacement of abdominal viscera, loss of normal diaphragm
Ex. traumatic hernia -> acute (hit by car) or chronic (small intestine herinated)
What are the 3 types of lung patterns?
Alveolar, interstitial, and bronchial patterns
What is a lung pattern?
Increased pulmonary opacity that corresponds to a particular component of the lung
What are components of the parenchyma?
Alveoli = air-filled sacs
Bronchial walls = airways
Interstitial tissue = framework of the lungs
Pulmonary vessels = creates most of the normal background opacity
What happens with bronchitis?
Thickened walls and coughing
Should alveoli and bronchi contribute to the background opacity?
No because they are air filled
What creates most of the normal background opacity?
Arterties and veins
What does pulmonary disease usually result in?
Increased lung opacity
