3] Assessment of the Film
3.1] Heart
Heart size
The heart can be seen to lie almost centrally within the chest and can be up to 50% of the chest diameter on a PA film. On an AP film heart size can be allowed up to 60% of the chest wall diameter.
‘Cardiothoracic ratio’
We express the size as a ratio of heart size to chest wall size.
How to Assess Cardiothoracic ratio
Click on the numbered buttons below to see how to assess cardiothoracic ratio
Heart borders
The heart borders seen on a CXR represent particular parts of anatomy of the heart as shown.
The outline of the descending aorta can be seen behind the heart extending vertically downwards.
