Chest radiograph assessment using ABCDEFGHI
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ABCDEFGHI can be used to guide a systematic interpretation of chest x-rays.
Assessment of quality / Airway
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 to each other; look for indwelling lines or objects
Bones and soft tissues
Scan the bones for symmetry, fractures, osteoporosis, and lesions. Evaluate the soft tissues for foreign bodies, swelling, and 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 the heart shape, calcifications, and prosthetic valves.
Check the hemidiaphragms for position (the right is commonly slightly higher than the left due to the liver) and shape (may be flattened bilaterally in chronic asthma or emphysema, or unilaterally in case of tension pneumothorax or foreign body aspiration). Look below the diaphragm for free gas.
Effusions / Extrathoracic soft tissue
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 the lateral film for small posterior effusions (more sensitive for small effusions).
Fields, fissures and foreign bodies
Check lungs 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.
Great vessels / gastric bubble
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 in the appropriate clinical setting) and tracheal deviation (which may indicate a mass effect, e.g. from large goiter, or tension pneumothorax). In children, be careful not to mistake the thymus for a mass!
In most cases, an impression is worthwhile as it not only forces you to synthesize all the findings together but acts as a double check.