IMAGING - Thoracic Radiograph Interpretation Flashcards
Identify the following features on this normal right lateral radiograph of the thorax
(T/F) Cats have a normal degree of lung retraction on radiography at the level of the L1 vertebrae
TRUE.
What are the five classifications of lung patterns?
Bronchial
Alveolar
Interstitial
Nodular
Vascular
What are the five main distributions of lung patterns?
Perihilar
Patchy
Cranioventral
Focal
Diffuse
What is perihilar distribution?
Perihilar distribution is distribution around the lung hilus
What are bronchial lung patterns?
Bronchial lung patterns are when the walls of the bronchi appear more visible and radio-opaque due to thickening and/or mineralisation. End-on bronchi will appear as radio-opaque rings, and the walls of the longitudinal bronchi will appear as thickened radio-opaque parallel lines
List five common differentials for bronchial lung patterns
Age-related mineralisation
Normal feature in chondrodystrophic breeds
Chronic bronchitis
Bronchopneumonia (presents with bronchio-alveolar pattern)
Asthma (presents with bronchio-interstitial pattern)
What are alveolar lung patterns?
Alveolar lung patterns are when the alveoli have a coalescing fluid/soft tissue opacity resulting in a loss of detailing of the pulmonary vessels (as the vessels are composed of soft tissue and fluid so will blend into the alveolar pattern)
What are two hallmarks of alveolar lung patterns?
Air bronchogram
Lobar sign
What is an air bronchogram?
An air bronchogram is where there are well delineated gas-filled bronchi and bronchioles surrounding by alveoli with a fluid/soft tissue opacity
What is the lobar sign?
The lobar sign is a sharply demarcated border between a normal lung lobe and a lung lobe with increased opacity
List six common differentials for alveolar lung patterns
Atelectasis
Neoplasia
Pulmonary oedema
Pulmonary haemorrhage/contusions
Aspiration pneumonia
Bronchopneumonia (presents with bronchio-alveolar pattern)
How do lung patterns typically distribute in left-sided congestive heart failure in dogs?
Perihilar distribution
How do lung patterns typically distribute in left-sided congestive heart failure in cats?
Patchy distribution
How do lung patterns typically distribute in bronchopneumonia?
Cranioventral distribution
Identify the lung patterns on this radiograph of a dog with aspiration pneumonia
The radio-opaque rings and parallel lines are signs of bronchial lung patterns - this only occurs if there is bronchial inflammation associated with the aspiration pneumonia - and the air bronchogram and coalescing area of fluid/soft tissue opacity alevoli are signs of an alveolar lung pattern.
How do lung patterns typically distribute in pulmonary heamorrhage/contusions?
Patchy distribution
How do lung patterns typically distribute in with lung masses?
Focal distribution
What are interstitial lung patterns?
Interstitial lung patterns are an increase in interstitial opacity caused by cellular, fluid or fibrotic change. There will be no loss of detailing of pulmonary vessels
List four common differentials of interstitial lung patterns
Age-related changes
Early stage left-sided congestive heart failure
Neoplasia
Asthma (presents with bronchio-interstitial pattern)
Why do young animals present with interstitial lung patterns?
Young animals have increased fluid within their insterstitium, causing an increase in interstitial opacity
Why do older animals present with interstitial lung patterns?
Older animals have fibrosis of the insterstitium, causing an increase in interstitial opacity
What are some of the other signs of feline asthma on radiographs?
Bronchial to broncho-interstitial lung patterns
Hyperinflation of the lungs
Collapse of the right middle lung lobe due to hyperinflation
What is a nodular lung pattern?
A nodular lung pattern is the presence of interstitial nodules. The nodules can either be solid or filled with gas
List three common differentials of nodular lung-patterns
Age-related changes (pleural plaques)
Metastaic neoplasia
Parasitic
At what size of nodules would you be concerned about metastatic neoplasia?
Nodules between 5 - 40mm can be indicative of metastatic neoplasia
What are vascular lung patterns?
Vascular lung patterns are increased or decreased pulmonary vessel size
How can you tell if the pulmonary vessels are a normal size?
Normal pulmonary vessels should be no wider than the width of the fourth rib on a lateral radiograph, and no wider than the ninth rib on a ventrodorsal (VD) radiograph
How can you use the summation shadow to assess the size of the pulmonary vessels?
When the pulmonary vessels overlap the ninth rib, the shadow should form a square shape. When the vessel is larger, the summation shadow will elongate horizontally (look more rectangular), when the vessel is smaller, the shadow will elongate vertically
Which three differentials should you consider if the pulmonary arteries appear larger than the pulmonary veins on a radiograph?
Heartworm
Lungworm
Pulmonary thromboembolism
Which two differentials should you consider if the pulmonary veins appear larger than the pulmonary arteries on a radiograph?
Left-sided heart failure
Left-to-right shunt
Which two differentials should you consider if the pulmonary arteries and veins are both enlarged?
Left-sided congestive heart failure
Left-to-right shunt
Which three differentials should you consider if the pulmonary arteries and veins are decreased in size?
Overinflation of the lungs
Hypovolaemia
Hypoperfusion
What size should a normal heart be in a dog?
Should take up 2.5 to 3.5 intercostal spaces
2/3 of the height of the thorax on lateral view
2/3 of the width of the thorax on ventrodorsal view
What size should a normal heart be in a cat?
Should take up 2 intercostal spaces
2/3 of the height of the thorax on lateral view
2/3 of the widge of the thorax on ventrodorsal view
Identify the specific heart chambers on this normal lateral radiograph of the thorax
Identify the specific heart chambers on this normal ventrodorsal radiograph of the thorax
What are two of the key signs of cardiomegaly on a radiograph?
Enlarged cardiac silouette
Dorsal displacement of the trachea
What is the most common cardiomyopathy seen in cats?
Hypertrophic cardiomyopathy
(T/F) It is easy to detect hypertrophic cardiomyopathy in cats on radiographs
FALSE. Cardiac enlargement due to hypertrophic cardiomyopathy is usually only obvious in severe cases
How can hypertrophic cardiomyopathies present on ventrodorsal radiographs?
Hypertrophic cardiomyopathies may appear ‘valentine heart shaped’ on ventrodorsal radiographs
What is the characteristic feature of a pericardial effusion on a radiograph?
Large rounded heart with sharp margins
What are the characteristic features of a mediastinal mass on a radiograph?
Increased soft tissue opacity at the mediastinum and displacement of neighbouring structures
Where are masses most commonly seen within the mediastinum?
Cranial mediastinum
What can be indicative signs of left sided congestive heart failure on radiography?
Perihilar or patchy alveolar signs
Enlarged pulmonary veins
Cardiomegaly
What can be indicative signs of right sided congestive heart failure on radiography?
Hepatomegaly
Pleural effusion
Pericardial effusion
Peritoneal effusion
Cardiomegaly
(T/F) The oesophagus is normally not visible on radiography
TRUE.
What are the characteristic signs of megaoesophagus on a radiograph?
- Dilated, air filled oesophagus with increased visibility of the oesophageal walls
- Ventral displacement of the trachea
- Tracheal stripe sign
What is the tracheal stripe sign?
The tracheal stripe sign is the increased visibility of the tracheal wall as a result of gas in the oesophagus
Which radiograph finding is commonly associated with megaoesophagus?
Aspiration pneumonia as megaoesophagus causes regurgitation which can cause aspiration
What are three characteristic signs of pleural effusion on a radiograph?
Decreased visualisation of the cardiac shadow
Retraction of the lung lobes surrounded by fluid opacity
Scalloped margins of the lung
What are the three characteristic signs of a pneumothorax on a radiograph?
- Heart elevated from the sternum
- Retraction of the lung lobes with free gas between the lung and the thoracic wall
- Increased lung opacity
What are two characteristic features of a diaphragmatic rupture on a radiograph?
Presence of abdominal structures in the thorax
Loss of visualisation of the diaphragm
What are the characteristic signs of a peritoneopericardial diaphragmatic hernia on a radiograph?
Presence of abdominal contents within the pericardium
