This is a basic article for medical students and other non-radiologists
Increased cardiothoracic ratio describes widening of the cardiac silhouette on a chest radiograph. This is only of use when making an assessment of a PA chest x-ray since the AP chest x-ray causes the artefactual magnification of the heart and the cardiothoracic ratio is altered.
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Reference article
This is a summary article; read more in our article on the increased cardiothoracic ratio.
Summary
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pathophysiology
- enlargement of the heart
- global or specific chamber enlargement
- enlargement of the heart
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role of imaging
- identify the increased CTR
- determine whether this represents cardiomegaly
- look for any signs of heart failure
Radiographic features
Chest radiograph
- use a PA chest x-ray
- a cardiothoracic ratio above 50% describes cardiomegaly
- measure the heart at its widest point
- measure the thorax at its widest point
- divide the cardiac dimension by the thoracic dimension
- do NOT use an AP chest x-ray
- the mediastinum is magnified
- an increased cardiothoracic ratio is much less specific
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