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CXR: From A to Zigzag

Joshua Hight Larson MD, PhD and Michael Aref MD, PhD


  • I. Identify: Make sure you have the right film (patient and time).
  • Q. Quality: Assess penetration (“white” → underpenetrated, “dark” → overpenetrated). Make sure the entire chest is viewable on the film, from apices to bases including the costophrenic angles. Count the number of ribs to assess inspiratory effort, < 10 will mimic pathology.
  • A. Airway, aorta, and adenopathy: Follow trachea down through carina and both mainstem bronchi. Look for deviations, obstruction, and masses. Identify aortic knob on LEFT, assess width, tortuosity and calcification. Adenopathy, either peritracheal or hilar, is also assessed.
  • B. Bones and breast shadow: Inspect the bones for radiographic density, fractures, lytic lesions, or bony deformity. Identify first rib, trace entire path and repeat for each rib to identify fractures. Assess rib spacing. Trace clavicle, scapula, and humerus to identify any fractures. Vertebra should be rectangular and stacked vertically. Evaluate the breast shadows for gross asymmetry, evidence of prior surgery, and any gross calcification.
  • C. Cardiac silhouette: Look for air around heart and mediastinum. Assess width of mediastinum. Try to see clear heart borders on all sides -- if not, think about silhouette signs to localize disease to RML or lingula. In PA view only use finger to measure distance of RIGHT border past mid-spine and add to the left border. If touching or going past ribs, think “enlarged”.
  • D. Diaphragm: Assess the diaphragm(s) with attention to the contour, elevation and costophrenic angles, bilaterally. Costophrenic angles should be sharp — blunting in pleural effusion. The right hemidiaphragm should be higher than the left. Check for free air. If diaphragm/lung borders obscured, think about silhouette signs again to localize a pathologic process to the RLL and LLL.
  • E. Everything else: Review everything else around the lung fields including the subcutaneous soft tissues and pleural boundaries. Examine soft tissue around chest and in neck for masses, subcutaneous emphysema, or causes of tracheal shift.
  • F. Fields, fluid, and foreign objects: Finally, review the lung fields themselves looking for evidence of effusion, infiltrate, masses, and pattern of vascularity. Look at perihilar regions to identify arteries (superior) and veins (inferior). Assess extension (e.g. PTX) and prominence (e.g. CHF) of these markings from hila to periphery. Note contour of the outer lungs to identify any pathology associated with the pleura. Compare apices to lower lungs. Take a couple steps back from the film and try to identify any subtle masses. Identify foreign objects, trace the course of arterial and venous lines as well as noting pacemakers and where they travel. Note evidence of previous surgery such as wire loops and staples. Note chest tubes, NGT/OGT, OETT, or tracheostomy.
  • G. Gastric air bubble: Look for gastric air bubble.
  • H. History: Correlate what you see with the clinical picture. Review older films to see if your findings have been stable over time or if they are new. Remember to confirm PA film findings on the lateral film to determine if they are “real”.




Crausman RS, Chest. 1998 Jan;113(1):256-7

Goodman LR, Felson’s Principles of Chest Roentgenology, 2nd Ed., W.B. Saunders Co., Philadelphia, PA, 1999