Small animal cardiac radiography

Question 1

What are the indications for thoracic radiography?

Answer 1

• identification, location and quantification of lesions
• identification of lesions too small to produce clinical signs
• assess effectiveness of treatment
• L heart failure
• identify cause of breathlessness/ cough

Question 2

What are some problems with thoracic radiography?

Answer 2

Difficult to demonstrate radiographs of diagnostic quality:

• movement blur
• wide radiographic contrast
• interpretation
• breed normals/ age normals
• inspiratory/ expiratory

Question 3

What positioning would you use for thoracic radiography?

Answer 3

Lateral - usually right but can do left –> heart

Both laterals–> lung metastases

Dorsoventral–> heart

Ventrodorsal–> lungs

Standing lateral
Standing erect
Recumbent VD with horizontal film

Question 4

How do you interpret thoracic radiographs?

Answer 4

• Assess technical quality (PCCELA, inspiratory or expiratory)
• Assess everything other than the heart and lungs–> peripheral soft tissue structures, anterior abdominal contents, thoracic skeleton, cranial and caudal mediastinum, diaphragm, pleural space
• Assess the respiratory system
• Assess the cardiac silhouette

Question 5

What should the cardiac silhouette look like?

Answer 5

Breed and age variation with dogs

Rule of thumb for lateral= 3.5 rib spaces max

Rule of thumb for DV= 2/3 width of thorax at rib 6 max

The vertebral heart scoring system:

• Length (L) is measured on lateral vs number of vb bodies (starting at the cranial edge of T4)
• Width (W) measured similarly
• VHS= L + W
• Average in dogs is 9.7 (range 8.5-10.5), 8 in cats (breed specific values are available)

Question 6

How does pericardial effusion look different to cardiomegaly?

Answer 6

Whole cardiac silhouette grossly enlarged
Globular appearance
Outline distinct as no movement