ABCDEFGHI can be used to guide a systematic interpretation of chest x-rays.
Assessment of quality
The quality of the image can be assessed using the mnemonic PIER:
- position: is this a supine AP file? PA? Lateral?
- inspiration: count the posterior ribs. You should see 10 to 11 ribs with a good inspiratory effect
- exposure: well-exposed films have good lung detail and an outline of the spinal column
- rotation: the space between the medial clavicle and the margin of the adjacent vertebrae should be roughly equal on each other; look for indwelling lines or objects
Bones and soft tissues
Scan the bones for symmetry, fractures,osteoporosis, or metastatic lesions. Evaluate the soft tissures forforeign bodies, edema, or subcutaneous air.
Evaluate the heart size: the heart should be <50% of the chest diameter on PA films and <60% on AP films. Check for heart shape, calcifications, and prosthetic valves.
Check diaphragms for position (the right is slightly higher than the left due to the liver) and shape (may be flat in asthma or COPD). Look below the diaphragms for free air.
Pleural effusions may be large and obvious or small and subtle. Always check the costophrenic angles for sharpness (blunted angles may indicate small effusions). Check a lateral film for small posterior effusions.
Fields and fissures
Check lung fields for infiltrates (interstitial vs.alveolar), masses, consolidation, air bronchograms, pneumothoraces,and vascular markings. Vessels should taper and should be almost invisible at the lung periphery.
Evaluate the major and minor fissures for thickening or fluid.
Check aortic size and shape and the outlines of pulmonary vessels. The aortic knob should be clearly seen.
Hila and mediastinum
Evaluate the hila for lymphadenopathy,calcifications, and masses. The left hilum is normally higher than the right. Check for widening of the mediastinum (which may indicate aortic dissection) and tracheal deviation (which may indicate a mass effect or tension pneumothorax). In children, be careful not to mistake the thymus for a mass!
In most cases an impression is worth while as it not only forces you to synthesise all the findings together but acts as double check.
- frontal (PA/AP) projection
- lateral projection
- lateral decubitus
- chest x-ray in the exam setting
- cardiomediastinal contour
lines and stripes
- anterior junction line
- posterior junction line
- right paratracheal stripe
- left paratracheal stripe
- posterior tracheal stripe / tracheo-oesophageal stripe
- posterior wall of bronchus intermedius
- right paraspinal line
- left paraspinal line
- aortic-pulmonary stripe
- aortopulmonary window
- azygo-oesophageal recess
Synonyms & Alternative Spellings
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|ABCDEFGHI: The way to interpret chest X-Rays||✗|