Assessment of cardiomediastinal contours on chest x-ray (approach)

Described below is one approach to systematic assessment and associated pathology of the cardiomediastinal contours on chest x-ray.

Mediastinum

• size: widened mediastinum can be seen in aortic dissection, traumatic aortic injuries
• abnormal contour, e.g. lymphadenopathy, anterior mediastinal mass
• abnormal gas pattern, e.g. pneumomediastinum, hiatus hernia

Heart (cardiac silhouette)

• assess position (frontal view): normally one-third right of midline and two-thirds left of midline
• assess borders and both frontal and lateral for silhouette sign and abnormal appearance
• pericardial fat pad (frontal view): normally in the cardiophrenic angle(s)
• assess overall size
  • normally the cardiothoracic ratio <0.50 on a PA chest x-ray obtained in full inspiration
  • can be enlarged most commonly in cardiomegaly and pericardial effusion