Thoracic radiograph interpretation

Question 1

What does good thoracic radiograph interpretation do for you?

Answer 1

• 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

Question 2

What type of cardiac disease (pressure vs volume overload) are thoacic radiographs good for discerning?

Answer 2

• Volume overload

- Most diseases in dogs are volume overload (e.g. mitral valve regurgiation or endocardiosis)

Question 3

What three things can often lead to diagnosis for cardiac disease?

Answer 3

1. Solid radiographic interpretation
2. Good cardiac examination
3. Knowledge of common diseases

Question 4

What are three common radiography pitfalls?

Answer 4

• Position
• Technique
• Anatomical variation

Question 5

Advantages of DV

Answer 5

• Pulmonary vessels
• Cardiac silhouette is not as elongated
• Better to see the heart with pleural effusion

Question 6

Advantages of VD

Answer 6

• Can see the vena cava very well

Question 7

Normal cardiac size: dog heart lateral

Answer 7

• Height: Cardiac base < 2/3 chest cavity height (apex to spine)
• Width: <2.5-3.5 intercostal spaces

Question 8

Normal cardiac size: dog heart dorsoventral projection

Answer 8

• Length: <5 intercostal spaces (<6 on VD)

- Width: Maximal width <2/3 width of chest cavity at same level

Question 9

Normal cardiac size: cat heart lateral

Answer 9

• Height: <2/3 chest cavity height
• Width: less than 2.5-3.5 intercostal spaces
• Cardiac apex SHOULD NOT OVERLAP with diaphragm

Question 10

Normal cardiac size: cat heart dorsoventral view

Answer 10

• 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

Question 11

Which chamber tends to be enlarged if heart is taller than normal on a lateral view (for dogs)?

Answer 11

Left heart enlargement

Question 12

Which chamber tends to be enlarged if heart is wider than normal on a lateral view (for dogs)?

Answer 12

• Right heart enlargement

Question 13

Which chamber tends to be enlarged if heart is taller than normal on a DV/VD view (for dogs)?

Answer 13

• Usually left sided enlargement

Question 14

Which chamber tends to be enlarged if heart is wider than normal on a DV/VD view (for dogs)?

Answer 14

• Left or right heart

Question 15

Chamber at 1-2 o’clock on lateral view?

Answer 15

• Left atrium

Question 16

Chamber at 4-6 o’clock on lateral view?

Answer 16

• Left ventricle

Question 17

Chamber at 7-8 o’clock on lateral view?

Answer 17

Right ventricle

Question 18

Chamber at 9-10 o’clock on lateral view?

Answer 18

Right atrium

Question 19

Chamber at 10-11 o’clock on lateral view?

Answer 19

• Aorta and main pulmonary artery

Question 20

Chamber at 1-2 o’clock on DV view?

Answer 20

• Main pulmonary artery

Question 21

Chamber at 2-3 o’clock on DV view?

Answer 21

Left auricle

Question 22

Chamber at 4-6 o’clock on DV view?

Answer 22

Left ventricle

Question 23

Chamber at 7-8 o’clock on DV view?

Answer 23

• Right ventricle

Question 24

Chamber at 9-11 o’clock on DV view?

Answer 24

Right atrium

Question 25

LOOK AT A RADIOGRAPH FOR EXAMPLE OF WHERE AORTA AND LEFT ATRIUM ARE

Answer 25

- Just do it

Question 26

What is normal ratio of aorta and caudal vena cava?

Answer 26

1:1 on lateral view

Question 27

Location of pulmonary artery and pulmonary vein relative to each other on lateral projection?

Answer 27

- Artery is dorsal | - Vein is ventral

Question 28

Location of pulmonary artery and pulmonary vein relative to each other on DV projection?

Answer 28

- Artery is outside | - Pulmonary vein is more medial

Question 29

Normal size of pulmonary vasculature

Answer 29

- 7th-9th rib, the vessel as it crosses the rib should not be wider than the 7th, 8th, or 9th rib

Question 30

Causes of pulmonary vessel overcirculation

Answer 30

- Ventricular septal defect | - Patent ductus arteriosus

Question 31

Causes of pulmonary vessel undercirculation

Answer 31

- Severe pulmonic stenosis

Question 32

Causes of pulmonary artery enlargement

Answer 32

- 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

Question 33

Pulmonary venous hypertension

Answer 33

- Usually occurs prior to left heart failure and may manifest as engorged pulmonary veins relative to arteries

Question 34

Caudal vena cava enlargement

Answer 34

- 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)

Question 35

Ductus bump

Answer 35

- PDA causes a dilation of the descending portion of the aorta (turbulence of the ductus) noted on DV or VD view

Question 36

Post-stenotic dilation of PS

Answer 36

- 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

Question 37

Post-stenotic dilation of SAS

Answer 37

- 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

Question 38

Bronchial pattern appearance

Answer 38

- Doughnuts and train tracks | - overall increased opacity of airways

Question 39

Interstitial pattern appearance

Answer 39

- Cloudy parenchyma - Obscures edges and vessels - Can be patchy or focal

Question 40

Alveolar pattern appearance

Answer 40

- Very progressed interstitial (flooded alveoli) - Bronchi are visible (air bronchogram) - Parenchyma dense to consolidated

Question 41

Consolidated lungs

Answer 41

- Dense alveolar pattern without an air bronchogram

Question 42

Vascular pattern of lungs

Answer 42

- Generalized enlarged pulmonary vessels (arteries and veins)

Question 43

Do normal thoracic radiographs rule out airway disease or inflammation?

Answer 43

- NOPE | - Especially in cats

Question 44

What can lead to an interstitial pattern?

Answer 44

Generally caused by infiltration of inflammatory fluid, hemorrhage, or neoplasia into tiny alveolar spaces - Not diffuse

Question 45

What can lead to an alveolar pattern?

Answer 45

- 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"

Question 46

What pattern is often seen with pneumonia

Answer 46

- Alveolar pattern | - If aspiration, often cranial ventral opacity in the lung

Question 47

What are the three classic findings of radiographic left heart failure?

Answer 47

1. Left heart enlargement (especially left atrium) 2. Pulmonary venous enlargement 3. Interstitial opacity, especially around vessels (pulmonary edema secondary to increased hydrostatic pressure secondary to venous congestion)

Question 48

What are the 3 hallmarks of the reverse D on a dorsoventral view secondary to right heart pressure load?

Answer 48

1. Right ventricle enlargement 2. Right atrial enlargement 3. Main pulmonary trunk bulge (also enlarged right PA)

Question 49

What disease process should come to mind when you see a reverse D on dorsoventral view?

Answer 49

- Right heart pressure overload (e.g. pulmonary arterial hypertension or pulmonic stenosis)

Question 50

What two things can occur with feline left sided congestive heart failure?

Answer 50

- Pleural effusion or interstitial pattern (pulmonary edema)