Lungs

Question 1

Clinical significance

Answer 1

• Diseases that involve the cardiovascular system and those that involve the pulmonary system have similar signs
• Assessment of either system requires a good understanding of the anatomy and circulation dynamics of the pulmonary vasculature bed
• Thoracic radiography is frequently performed to examine patients with expected neoplasia or clinical signs of coughing or dyspnea
• Coughing or dyspnea may be due to disease of the heart, pleural space, trachea, lymph nodes, body wall, diaphragm, or lungs

Question 2

Anatomy

Answer 2

• 2 main pulmonary arteries originate from the main pulmonary trunk
• Left PA is more dorsal than the right
• One main pulmonary vein courses back from ea. lung to empty into the left atrium
• Similarly a bronchus supplies each lung
• The bronchus is always accompanied by an artery and vein–triad (bronchus is in the middle)

Question 3

Radiographic anatomy

Answer 3

• When you look at the pulmonary blood vessels you should see that they branch and taper toward the periphery
  
  • Should see these vessels clearly extend to the lung borders
• “Veins are venral and central”
• Caudal lobe pulmonary blood vessels are better seen in DV view
• Arteries and veins of the non-dependent (up) lung are easier to see
• In the L lateral view the right cranial lobar artery and vein should be the same size

Question 4

Radiographic anatomy: lung lesions

Answer 4

• In small animals, lung lesions generally are detected best in the non-dependent lung because the ‘up’ lung is better aerated and therefore provides better contrast of lesions
  
  • Ex: the DV view is better for evaluating the caudal lung lobes; LLAT is better for evaluating right lung lobes
• Other lesions (i.e. not lung) generally are best seen on the ‘down’ side because they are not distorted by magnification
• In large animals lung lesions are best detected in the lung closest to the cassette because lesions in the “far” lung are distorted due to magnification

Question 5

What are the 4 lung patterns?

Answer 5

1. Bronchial
2. Interstitial
3. Alveolar
4. Mixed

Question 6

Bronchial pattern

Answer 6

• Normally only main stem bronchi seen
• Smaller bronchi become visible with:
  
  • Mineralization
  • Cellular or fluid infiltration
• Increased conspicuity of the bronchial tree
• Ring shadows (donuts)
• Tram lines

Question 7

Interstitial pattern

Answer 7

• Often diffuse
• Structured pattern
  
  • Nodular pattern < 2cm
  • Mass lesions very distinct
  • Metastasis #1 DDx
• Unstructured pattern
  
  • Most difficult one to diagnose
  • Generalized haziness
  • Pulmonary lymphoma

Question 8

Alveolar pattern

Answer 8

• Alveoli no longer filled with air
• Air (radiolucent) replaced by soft tissue (increased) opacity
• Consolidation–air replaced by fluid or cells
  
  • Edema, blood, pus, neoplasia
• Atelectasis–air is squashed out of lung
  
  • Total atelectasis = lung collapse
  • Often assoc. w/ pleural disease

Question 9

Alveolar pattern: 4 types

Answer 9

• Air bronchograms
  
  • Air only in bronchioles–can see nothing else
• Border effacement
  
  • Only caused by alveolar pattern
• Lobar distribution
  
  • Fissure separating normal from abnormal lung lobe
• Labile
• Major pitfall: confusing an air bronchogram with a normal gas filled bronchus (w/ its pulmonary vein and artery on either side)

Question 10

Atelectasis vs. consolidation

Answer 10

• Atelectasis
  
  • Inc. soft tissue opacity
  • Dec. size of lung lobe
  • Shift of heart towards rib
• Consolidation
  
  • Inc. soft tissue opacity
  • Normal to inc. sized lung lobe
  • Heart remains in normal position

Question 11

Mediastinal shift

Answer 11

• Best seen on VD/DV radiograph
• Usually not apparent on the lateral
• Atelectasis may appear on lateral as lesion of inc. soft tissue opacity
• Lung atelectasis–mediastinum moves to side of decreased lung size
• If thoracic mass or fluid–mediastinum moves to opposite side and lung compensates

Question 12

Airway vs. non-airway

Answer 12

• Alrternative way of classification
• Helpful to determine further diagnostic approaches
• Airway: alveolar or bronchial pattern
  
  • Transtracheal aspiration or bronchoalveolar lavage
• Nonairway: interstitial pattern
  
  • Rather percutaneous or open aspiration/biopsy needed

Question 13

Interpretation: focal vs. non-focal

Answer 13

• Focal
  
  • Abscess
  • Granuloma
  • Neoplasia
• Multifocal
  
  • Neoplasia
  • Abscess
  • Fungal granuloma
  • Parasitic

Question 14

Mineralization

Answer 14

• Bronchial pattern
• Lesions
  
  • Histoplasmas granulomas in dogs
  • Aspirated barium contrast material
  • Neoplasia (dystrophic)
• Incidental
  
  • Pulmonary osseous metaplasia

Question 15

Blood vessels vs. nodules

Answer 15

• Blood vessels
  
  • Soft tissue (end on, inc. length, inc. opacity)
  • Well-marginated
  • Smaller to periphery
  • Associated with blood vessels
  • Tail sign
• Nodules
  
  • Any size
  • Same opacity (round)
  • Not as well marginated
  • Not assoc. w/ blood vessels