SA Thoracic imaging Flashcards
What conditions won’t come up on radiographs?
Acute viral pneumonia
Acute + chronic tracheobronchitis
Lungworm
Upper airway disease
What should you consider with your radiographic technique?
*Prevent rotation
*Wedges under sternum
*General anaesthesia vs. sedation?
*Beware of GA atelectasis
*Keep in sternal recumbency
*Always take DV first
What are the 3 steps of interpretation?
- Assess radiograph overall
- Systematic approach
3.Normal or Abnormal
Why does phase of respiration affect interpretation?
*Lungs larger + less opaque on inspiration
*Heart looks relatively smaller?
How does obesity affect interpretation?
*Wide mediastinum
*Increased apparent opacity of lungs
How does species difference affect interpretation?
*Psoas muscles in cats is seen
*Differences in cardiac shape/size and thoracic conformation
How does effect of recumbency affect interpretation?
*Different positions of diaphragmatic crura in left vs right lateral
*Cardiac silhouette differs
What does decreased opacity in the pleural space indicate?
*Pneumothorax
*Retraction of lungs from thoracic margins (and lung atelectasis)
*Elevation of cardiac silhouette from sternum
What does increased opacity indicate?
*Usually artefact - poor technique / obesity
*Due to increased fluid/cells or loss of air
Considering the ribs what should be assessed?
*All ribs assessed individually
*Check that they’re normal in number, shape, opacity, size + position
How should you classify mediastinum masses?
*Classify according to location
*Cranioventral
*Central
*Craniodorsal
*Caudoventral/ caudodorsal
Where is the most common location for mediastinal masses and why?
*Cranioventral
*Often lymph nodes / thymus
*May displace other mediastinal structures
What causes decreased opacity?
1.Increased gas
2.Decreased soft tissue/fluid
What conditions have apparent decreased opacity?
*Pneumothorax
*Pneumomediastinum
*Subcutaneous emphysema
What can cause diffuse decreased opacity?
*Artefact
*Hypovolaemia
*Hyperinflation
What can cause focal decreased opacity?
*Cavitatory lung lesion
*Emphysema
*Thromboembolus
How does lung swelling / collapse affect the mediastinum?
*Lung swelling = pushed mediastinum away
*Lung collapse = pulls mediastinum towards it
What is the most common cranioventral problem?
Pneumonia
What is the most common caudodorsal problem?
Oedema
What are generalised lung problems?
*Haemorrhage
*Metastatic neoplasia
*Atelectasis
*Oedema
*Fibrosis
*Bronchitis
What are peripheral lung problems?
*Parasitic pneumonia
*Contusion
*Infarction
*Metastases (nodules)
What are the 4 components of the lung?
*Bronchi
*Blood vessels
*Interstitial tissue
*Alveolar air spaces
What are bronchial patterns?
increased visibility of bronchial walls (Thickened or increased opacity)
What are the differential diagnoses of bronchial patterns?
*Calcification (increased opacity)
*Chronic bronchitis
*Peribronchial cuffing
What in the bronchi is a sign of chronic + severe disease?
Bronchiectasis = widened bronchi
What is an alveolar pattern?
*Cells+/- fluid replaces air in alveoli
*Increased lung opacity
*Border effacement of adjacent structures
*May see air bronchograms
*Lobar sign if entire lobe affected
What are the diffuse differential diagnoses for alveolar pattern?
*Pneumonia
*Oedema (non-cardiogenic/cardiogenic)
*Haemorrhage
What are the focal differential diagnoses for alveolar pattern?
*Pneumonia
*Oedema
*Haemorrhage
*Primary/secondary lung tumour
*Lobar collapse/atelectasis
*Infarct
*Lung lobe torsion
What is interstitial pattern?
*Cells or fluid in interstitial tissue
*Should not completely efface soft tissue structures (vessels, diaphragm etc)
*Blood vessels less distinctly seen
Why is interstitial pattern commonly thought to be artefactual?
Expiration
Obesity
Underexposure
What are the diffuse differential diagnoses of interstitial pattern?
*Artefact
*“Ageing”
*Lymphoma
*Diffuse metastases
*Pneumonitis (viral, parasitic, metabolic, toxic)
*Disease in transition
What can cause nodular interstitial pattern?
*Secondary neoplasia
*Artefactual nodules
*Mistaken for end of blood vessels or skin masses (nipples)
What does the cardiac silhouette include?
Cardiac silhouette is summation of heart, pericardial contents and pericardium
What are the 2 pathogenesis of backwards heart failure?
1.Vena caval congestion = hepatic congestion, ascites + pleural effusion
2. Pulmonary venous congestion = pulmonary oedema
What is the pathogenesis of forwards heart failure?
Pulmonary artery / aorta = reduced CO
Which side of the heart is cranial and what is the ratio of heart when looking from the side?
Right side = cranial
2:1 Right : Left
What is the vertebral heart score?
Compare size of heart (sum of lung and short axis) to vertebral length (T4)
What occurs with left sided disease?
*Tracheal elevation (to parallel to spine)
*Straightening of the caudal cardiac border
=both cause left ventricular enlargement
*Left atrial enlargement or “tenting”
What occurs with right sided disease?
*Increase in cardiac width and rounding of right side
*Increased R:L ratio
*Reverse D shape on DV view
*Sternal contact
How would you assess size of cranial lobar vessels?
Usually not significantly wider than the proximal third of the fourth rib
How would you assess size of caudal lobar vessels?
Usually not significantly wider than the ninth rib where they cross
What can be seen with pulmonic stenosis?
*Can see post-stenotic bulge of the main pulmonary artery
*Consequent right-sided enlargement due to pressure overload
What is seen with patent ductus arteriosus?
Most common congenital CV anomaly
*3 knuckle buldge seen
*Increased pulmonary flow, left sided enlargement and aortic enlargement
What is seen in mitral valve disease?
*Tends to be smaller breed dogs
*Typical pattern of progressive left atrial enlargement
*Ultimately pulmonary oedema (when in failure)
What is seen in dilated cardiomyopathy?
*Often larger breed dogs
*Often significant cardiomegaly if clinical (may be less obvious if deep chested)
*Significant left atrial +/- right sided enlargement
What is seen in feline cardiomyopathies?
*Hypertrophic (HCM) (the most common)
-Dilated (DCM)
-Restrictive (RCM)
-Unclassified (UCM)
*Chamber enlargement less specific in cats
*May see more generalised cardiomegaly
What is seen with a pericardial effusion?
*Fluid within pericardial space (idiopathic/secondary to masses)
*Round and sometimes well-defined cardiac silhouette (especially on DV)
What is seen with persistent right aortic arch?
*Left displacement of trachea and deviation to left consistent sign
*May see ventral tracheal deviation and focal megaoesophagus
What can result in microcardia?
*Hypovolaemia can result in microcardia and hypovascular lungs
