Chest X-ray                                                                                            

Interpretation

• Name & date
• AP or PA film
• Cardiac size (cardiothoracic ratio)
• Cardiac shape
• Lung vasculature
• Lung parenchyma
• Skeleton & soft tissues
• Extraneous devices (chest drains, ECG leads, ET tube, central lines, etc)

Cardiothoracic Ratio (CTR)

CTR = (1+2) / 3

1 = max distance between left heart & midline
2 - max distance between right heart & midline
3 = max distance between inner border of ribs

In this example:
1 = 42, 2 = 66, 3 = 140
thus CTR = 108/140 or 77%

Cardiac Chambers 

Common Variations

Expiratory Film

Note the 5th rib crosses the diaphragm at its midpoint. There is apparent pulmonary plethora and cardiomegaly dur to the reduced pulmonary volume

Thymus

This is often seen in newborn and infants as a sail like shadow. Sometimes it may be more diffuse and mimic cardiomegaly but then the borders fade and allow distinction. 

Right Sided Arch

Note that the normal aortic knuckle is absent and that the upper mediastinum appears narrow as a result. This is a common finding in tetralogy of Fallot.

Hemi-diaphragm

Note the elevated right diaphragm. This was due to phrenic nerve damage at the time of mitral valve replacement (note the white circle). This is a not infrequent occurrence following cardiac surgery.
 

This page was last edited 16/2/2004