Thoracic radiograph interpretation Flashcards
What does good thoracic radiograph interpretation do for you?
- Localize a problem to an organ system in patients with respiratory symptoms, e.g. cardiac, pulmonary airway, pleural space, or mediastinal disease
- Assess changes in heart shape and size AND assess the presence or absence of heart failure (fluid)
- Evaluate intrathoracic blood vessels
- Chest conformation
What type of cardiac disease (pressure vs volume overload) are thoacic radiographs good for discerning?
- Volume overload
- Most diseases in dogs are volume overload (e.g. mitral valve regurgiation or endocardiosis)
What three things can often lead to diagnosis for cardiac disease?
- Solid radiographic interpretation
- Good cardiac examination
- Knowledge of common diseases
What are three common radiography pitfalls?
- Position
- Technique
- Anatomical variation
Advantages of DV
- Pulmonary vessels
- Cardiac silhouette is not as elongated
- Better to see the heart with pleural effusion
Advantages of VD
- Can see the vena cava very well
Normal cardiac size: dog heart lateral
- Height: Cardiac base < 2/3 chest cavity height (apex to spine)
- Width: <2.5-3.5 intercostal spaces
Normal cardiac size: dog heart dorsoventral projection
- Length: <5 intercostal spaces (<6 on VD)
- Width: Maximal width <2/3 width of chest cavity at same level
Normal cardiac size: cat heart lateral
- Height: <2/3 chest cavity height
- Width: less than 2.5-3.5 intercostal spaces
- Cardiac apex SHOULD NOT OVERLAP with diaphragm
Normal cardiac size: cat heart dorsoventral view
- Length: similar to dog (<5 intercostal spaces on DV or <6 on VD)
- Width: maximal width <1/2 width of chest cavity at same level
Which chamber tends to be enlarged if heart is taller than normal on a lateral view (for dogs)?
Left heart enlargement
Which chamber tends to be enlarged if heart is wider than normal on a lateral view (for dogs)?
- Right heart enlargement
Which chamber tends to be enlarged if heart is taller than normal on a DV/VD view (for dogs)?
- Usually left sided enlargement
Which chamber tends to be enlarged if heart is wider than normal on a DV/VD view (for dogs)?
- Left or right heart
Chamber at 1-2 o’clock on lateral view?
- Left atrium
Chamber at 4-6 o’clock on lateral view?
- Left ventricle
Chamber at 7-8 o’clock on lateral view?
Right ventricle
Chamber at 9-10 o’clock on lateral view?
Right atrium
Chamber at 10-11 o’clock on lateral view?
- Aorta and main pulmonary artery
Chamber at 1-2 o’clock on DV view?
- Main pulmonary artery
Chamber at 2-3 o’clock on DV view?
Left auricle
Chamber at 4-6 o’clock on DV view?
Left ventricle
Chamber at 7-8 o’clock on DV view?
- Right ventricle
Chamber at 9-11 o’clock on DV view?
Right atrium
LOOK AT A RADIOGRAPH FOR EXAMPLE OF WHERE AORTA AND LEFT ATRIUM ARE
- Just do it
What is normal ratio of aorta and caudal vena cava?
1:1 on lateral view
Location of pulmonary artery and pulmonary vein relative to each other on lateral projection?
- Artery is dorsal
- Vein is ventral
Location of pulmonary artery and pulmonary vein relative to each other on DV projection?
- Artery is outside
- Pulmonary vein is more medial
Normal size of pulmonary vasculature
- 7th-9th rib, the vessel as it crosses the rib should not be wider than the 7th, 8th, or 9th rib
Causes of pulmonary vessel overcirculation
- Ventricular septal defect
- Patent ductus arteriosus
Causes of pulmonary vessel undercirculation
- Severe pulmonic stenosis
Causes of pulmonary artery enlargement
- Pulmonary arterial hypertension
- Sometimes terminal portions will be attenuated, while proximal portions are very large in chronic PAH
- In heart worm disease, pulmonary arteries may become markedly tortuous
Pulmonary venous hypertension
- Usually occurs prior to left heart failure and may manifest as engorged pulmonary veins relative to arteries
Caudal vena cava enlargement
- May be enlarged in cases of systemic venous congestion as may occur with elevations in right heart filling pressure
- Compare to aorta on lateral film (1:1 is normal)
Ductus bump
- PDA causes a dilation of the descending portion of the aorta (turbulence of the ductus) noted on DV or VD view
Post-stenotic dilation of PS
- Dilation of main pulmonary artery caused by pulmonic stenosis often times seen on the DV radiograph in the 1:00-2:00 position
- This helps create the reverse D pattern noted radiographically with right ventricular pressure overload
Post-stenotic dilation of SAS
- Subaortic stenosis can cause a post-stenotic dilation of ascending aorta typically noted as a bulge in the cranial heart base region on a lateral radiograph
Bronchial pattern appearance
- Doughnuts and train tracks
- overall increased opacity of airways
Interstitial pattern appearance
- Cloudy parenchyma
- Obscures edges and vessels
- Can be patchy or focal
Alveolar pattern appearance
- Very progressed interstitial (flooded alveoli)
- Bronchi are visible (air bronchogram)
- Parenchyma dense to consolidated
Consolidated lungs
- Dense alveolar pattern without an air bronchogram
Vascular pattern of lungs
- Generalized enlarged pulmonary vessels (arteries and veins)
Do normal thoracic radiographs rule out airway disease or inflammation?
- NOPE
- Especially in cats
What can lead to an interstitial pattern?
Generally caused by infiltration of inflammatory fluid, hemorrhage, or neoplasia into tiny alveolar spaces
- Not diffuse
What can lead to an alveolar pattern?
- When tiny alveolar spaces are infiltrated with inflammatory fluid, hemorrhage, or neoplasia
- Soft tissue opacity highlights the larger airways, creating a hallmark dark “air bronchograms”
What pattern is often seen with pneumonia
- Alveolar pattern
- If aspiration, often cranial ventral opacity in the lung
What are the three classic findings of radiographic left heart failure?
- Left heart enlargement (especially left atrium)
- Pulmonary venous enlargement
- Interstitial opacity, especially around vessels (pulmonary edema secondary to increased hydrostatic pressure secondary to venous congestion)
What are the 3 hallmarks of the reverse D on a dorsoventral view secondary to right heart pressure load?
- Right ventricle enlargement
- Right atrial enlargement
- Main pulmonary trunk bulge (also enlarged right PA)
What disease process should come to mind when you see a reverse D on dorsoventral view?
- Right heart pressure overload (e.g. pulmonary arterial hypertension or pulmonic stenosis)
What two things can occur with feline left sided congestive heart failure?
- Pleural effusion or interstitial pattern (pulmonary edema)
