Imaging Flashcards
Outline a standard positioning technique for radiographing the thorax.
- Use a straightening wedge underneath the thorax to straighten the sternum
- Always take on expiration
- Beware under GA atelectasis can occur due to lateral recumbency
- Perform two view orthogonal to each other - ie DV and lateral
How can increased body condition affect thoracic radiographs?
- Wide mediastinum
- Increased opacity of the lungs
- Fat elevation of the heart (ventral)
What effect does the phase of respiration have on thoracic radiographs?
Inspiration causes the lungs to look larger and less opaque and the heart to relatively smaller
What factors can affect the appearance of a thoracic radiograph?
- Side of recumbency
- Phase of respiration
- BCS
- Species
What disease processes can lead to increased throacic opacity under radiograph?
- Lungs: Pneumonia (+distribution)
- Mediasteinum: Mediasteinal masses
- Pleural space: Pyothorax
What is meant by border effacement?
Two structures of the same radiographic opacity touching each other.
Outline the radiographic findings associated with a pleural effusion.
- Border effacement of heart and diaphragm
- Pleural fissures
- Retraction of lung margins from chest wall
- FLUID!
Describe the radiographic findings shown here.
What condition is associated with such findings?
- Raised cardiac shadow
- Lung atelectasis
- Retraction of the lung from thoracic margins
Which structures are found within the mediasteinum?
- Trachea
- Oesophagus
- Heart and great vessels
- Lymph nodes
Cranioventral mediasteinal masses can lead to what radiographic changes?
- widened mediastinum
- displacement of other cranio-ventral structures (trachea)
What factors can cause decreased opacity of the lungs on radiograph?
- Increased gas
- Decreased soft tissue/fluid
Name three conditions which can cause diffuse or focal decreases in radiographic lung opacity.
- Diffuse: hypovolaemia, hyperinflation, pneumothorax, subcut emphysema
- Focal: emphysema, thromboembolus, focal pneumothorax
What is a bronchial pattern?
What differentials are associated?
Increased opacity of the bronchial wall. Around hillus (not at periphery)
Differentials: Calcification, chronic bronchitis, peribronchial cuffing
Doughnuts and tramlines?
Bronchial pattern
What is an alveolar pattern?
Outline differentials for this finding.
Increased opacity in alveolus (air replaced with cells or fluid)
Differentials:
Diffuse: pneumonia, oedema, haemorrhage,
Focal: pneumonia, oedema, haemorrhage, tumours, atelectasis, infarct, lobar torsion
What is meant by a lobar sign?
A sharp line of demarcation between a lung lobe that is opaque (consolidated) and adjacent to one that is aerated.
What is an air bronchogram?
Alveoli have accumulated fluid and therefore only air filled bronchi are visible
What is an interstitial pattern?
Outline differentials for this finding.
Increased fluid or cells within the interstitium of the lungs
Differentials: pneumionitis, metastasis, artefacts
Cardiac shadow
The heart within the pericardium
The cardiac shadow is more round in which side of lateral recumbency?
Left
How do you calculate a vertebral heart score?
What is a normal value for a dog?
VHS = Long axis + short axis
The long and short axis are measured relative to the number of vertebrae they cover.
8.7-10
Left sided heart disease can cause what radiographic signs?
Raising of the trachea
Widening (tenting) of the atria
Straightening of the caudal cardiac border
Bronchial compression caudal to carina
What is the carina of the trachea?
The cartilage ridge at the trachea bifurcation (left of midline)
Right sided heart disease can cause which radiographic changes?
Increased width of the cardiac shadow
Rounding of the cranial border
Increase R:L ratio
Increased sternal contact (beware obesity)
DV view shows a reverse D
