What are the key steps in interpreting a chest radiograph?

Key Steps in Interpreting a Chest Radiograph

A systematic approach to chest radiograph interpretation is essential for accurate diagnosis and should follow a structured algorithm to ensure all critical elements are evaluated.

Initial Assessment and Technical Evaluation

• Begin by checking patient identification, date of examination, and radiograph quality, including proper penetration, rotation, and inspiration 1
• Confirm proper positioning by verifying that the medial ends of the clavicles are equidistant from the spinous processes and that 9-10 posterior ribs are visible above the diaphragm 2, 3
• Note the projection (PA vs. AP) as portable AP radiographs have lower sensitivity for detecting pneumothorax, hemothorax, lung contusions, and rib fractures 1

Systematic Review of Anatomical Structures

1. Airway and Mediastinum

• Trace the trachea and main bronchi, noting any deviation or narrowing 1
• Evaluate the cardiac silhouette for size (cardiothoracic ratio <0.5), shape, and contour abnormalities 2
• Assess mediastinal width and contour, looking for widening that might suggest aortic pathology or lymphadenopathy 1
• Examine the aortopulmonary window and hilar regions for abnormal masses or lymphadenopathy 1

2. Lung Parenchyma

• Systematically examine all lung zones (upper, middle, lower) for opacities, nodules, or masses 1
• Look for patterns suggesting specific pathologies: alveolar (airspace) opacities, interstitial patterns, or mixed patterns 4
• Compare side-to-side symmetry, as asymmetric findings often indicate pathology 3
• Evaluate for signs of chronic lung disease such as hyperinflation, bullae, or fibrotic changes 1

3. Pleura and Diaphragm

• Trace the pleural surfaces looking for effusions, pneumothorax, or pleural thickening 1
• Assess diaphragmatic contours for flattening, elevation, or depression 1
• Check costophrenic angles for blunting that might indicate small effusions 1

4. Bony Structures and Soft Tissues

• Examine ribs, spine, shoulders, and clavicles for fractures, lytic or blastic lesions 1
• Assess soft tissues for abnormal air, calcifications, or masses 1
• Look for surgical hardware, monitoring devices, tubes, and lines, confirming proper positioning 1

Integration and Interpretation

• Correlate radiographic findings with clinical information to narrow differential diagnoses 1
• Consider follow-up imaging with CT for further characterization when radiographic findings are abnormal or equivocal 1
• When interpreting chest radiographs, always follow a consistent systematic approach to avoid missing subtle but clinically significant findings 1, 5

Common Pitfalls and How to Avoid Them

• Satisfaction of search: after finding one abnormality, continue systematic review to avoid missing additional findings 5
• Underpenetration or overpenetration can mask pathology; request repeat imaging if technical quality is inadequate 3
• Portable AP radiographs have lower sensitivity; approximately 40% of patients with "normal" chest radiographs may have injuries detected on CT 1
• Overlapping structures can simulate pathology; use lateral views and comparison with prior studies when available 2
• Failure to recognize normal variants can lead to unnecessary additional imaging; familiarize yourself with common normal variants 6

Advanced Considerations

• In critically ill patients, daily radiographs may be necessary to monitor disease progression and placement of support devices 4
• Consider the limitations of chest radiography; it may miss up to 50% of pneumothoraces, pulmonary contusions, and rib fractures compared to CT 1
• New deep learning AI models can assist in detecting abnormalities with high sensitivity (88.4%) and may reduce interpretation time by 21% 5
• For specific clinical scenarios such as suspected interstitial lung disease or aortic dissection, CT provides significantly higher diagnostic accuracy 1