thoracic radiographs should be made at what phase of respiration?
full inspiration (to maximize the amount of gas within the thorax, so abnormal soft tissue opacities can be visualized)
How do you know you have caudal thoracic radiographs properly exposed in an adult large animal patient?
under-exposed (too white) cranial abdomen
Which lungs are best evaluated in recumbent thoracic radiographs?
- non-recumbent lung lobes are evaluated best (b/c the recumbent lungs cannot fully inflate d/t compression)
- R recumbent lateral- evaluate left lobes best
- L recumbent lateral- evaluate right lobes best
Which lungs are best evaluated in standing thoracic radiographs?
- the lobes closest to the film (sharper, less magnification, no concern with compression when standing)
- R standing lateral- right lobes evaluated best
- L standing lateral- left lobes evaluated best
Describe the vascular pulmonary pattern.
- increased or decreased prominence of pulmonary vascular structures (lungs don't look as black as they should be, can see defined vessels)
- may look like increased number of vessel (d/t smaller peripheral vessels becoming enlarged and more prominent)
What types of pathology cause a bronchial pattern?
- fluid and/ or cellular material within bronchial walls, bronchial lumens, and/or peribronchial space
- commonly associated with chronic inflammation and hypersensitivity
What are the subsets of bronchial pattern? (4)
- mineralization- age related change
- bronchiectasis- dilation of bronchi
- bronchial thickening- actual bronchial walls are thicker
- peri-bronchial edema- darker around each bronchus
What is the radiographic appearance of bronchiectasis?
- increased diameter of bronchus
- tram lines
What is the radiographic appearance of a bronchial pattern?
What causes an interstitial pattern?
accumulation of fluid and/or cells in the pulmonary interstitial space (connective tissue b/w airway and alveoli)
What are the types of interstitial pattern, and how does each appear radiographically?
- Unstructured interstitial: soft tissue haze that obscures the pulmonary vasculature; fluid and/or cells within the interstitium
- Structured interstitial: round, soft tissue opacities, solid or cavitated; aggregation of cells within the interstitium
- [must do FNA to Dx]
What is the general pathology behind an alveolar pattern?
- displacement of air from the distal spaces of the lung
- flooding of pulmonary acini with pus, edema, or blood
- collapse of airways
Describe how an alveolar pattern spreads.
acini are connected by pores that allow the fluid to spread; HOWEVER, pleural fissures act as a barrier, so fluid can't move b/w lung lobes unless it travels through the bronchi
How does an alveolar pattern appear radiographically?
"air bronchograms"- air-filled airways surrounded by soft tissue opacity; you CANNOT see the blood vessels around the airways
How can you diagnose the cause of an alveolar pattern?
trans-tracheal wash or bronchoalveolar lavage
What is a lobar sign?
- pattern of pathology outlines the lobe; diseased lung next to normal, aerated lung
- most commonly with alveolar pattern (sometimes with unstructured interstitial pattern)