What is the interpretation of this chest x-ray?

Chest X-Ray Interpretation: A Systematic Approach

To properly interpret a chest X-ray, you must use a standardized, systematic approach that examines all anatomical structures in a specific sequence to avoid missing critical findings. 1

Systematic Review Framework

The American College of Radiology recommends examining the following structures in order 1:

Mediastinum and Cardiac Assessment

• Evaluate tracheal position and patency - deviation may indicate mass effect or tension pneumothorax 1
• Assess mediastinal width and contours - widening >8 cm on PA view suggests aortic injury, dissection, or mass 1
• Measure cardiac size - cardiothoracic ratio >0.5 indicates cardiomegaly 1
• Check for pneumomediastinum - look for air tracking along mediastinal structures 1

Lung Parenchyma Evaluation

• Examine for focal opacities or consolidation using side-to-side comparison 1
• Assess interstitial patterns - reticular, nodular, or reticulonodular patterns may indicate interstitial lung disease 1
• Look systematically at all lung zones - upper, middle, and lower zones bilaterally to avoid perceptual errors 2

Pleural Assessment

• Evaluate for pneumothorax - visible pleural line with absent lung markings peripherally 1
• Check for pleural effusion - meniscus sign and blunting of costophrenic angles 1
• Assess for pleural thickening or plaques - may indicate asbestos exposure or chronic inflammation 1

Osseous and Soft Tissue Structures

• Examine all visible bones - ribs, clavicles, scapulae, vertebrae for fractures or lytic/blastic lesions 1
• Evaluate soft tissues - subcutaneous emphysema, masses, or asymmetry 1
• Assess diaphragm contours - elevation, flattening, or loss of normal contour may indicate pathology 1

Special Clinical Contexts

Trauma Patients

Pay particular attention to 1:

• Widened mediastinum (aortic injury)
• Rib fractures (especially first rib or multiple fractures)
• Pneumothorax or hemothorax
• Diaphragmatic injury

Suspected Pulmonary Embolism

• Westermark sign (focal oligemia) and Hampton's hump (peripheral wedge-shaped opacity) are suggestive but uncommon 1
• A normal chest X-ray in a patient with acute dyspnea and hypoxemia actually increases suspicion for PE 1

Suspected Aortic Disease

When unfolding of the aorta or other aortic abnormalities are detected 3:

• Chest X-ray alone is inadequate - sensitivity only 64% for widened mediastinum and 71% for abnormal aortic contour 3
• Proceed to definitive imaging with CT angiography (most common), MRI, or transesophageal echocardiography 3
• A completely normal chest X-ray does not exclude aortic dissection 3

Suspected Diaphragmatic Hernia

Initial chest X-ray findings may include 4:

• Abnormal bowel gas pattern in thorax
• Air-fluid levels above diaphragm
• Abnormal lucency or soft tissue opacity with mediastinal deviation
• Hemidiaphragm elevation
• Nasogastric tube curling into thorax (diagnostic)

However, chest X-ray has poor sensitivity (2-60% for left-sided, 17-33% for right-sided hernias) and CT is the gold standard 4

Critical Limitations to Recognize

Sensitivity Issues

• Up to 50% of pneumothoraces, pulmonary contusions, and rib fractures may be missed on standard AP radiographs 1
• Chest X-ray interpretation errors are predominantly perceptual (missing visible findings) rather than interpretive 2
• Early heart or lung disease may not cause visible changes on chest X-ray 5

When to Obtain Advanced Imaging

The American College of Radiology recommends CT or MRI for definitive diagnosis when 1:

• Clinical suspicion remains high despite normal or equivocal chest X-ray
• Subtle findings require further characterization
• Precise anatomical detail is needed for treatment planning

Common Pitfalls to Avoid

1. Failing to use a systematic approach - this is the primary cause of missed findings 2, 6
2. Satisfaction of search - stopping after finding one abnormality without completing full review 2
3. Over-reliance on chest X-ray - remember its limitations and obtain advanced imaging when clinically indicated 3, 1
4. Ignoring clinical context - chest X-ray findings must always be correlated with clinical presentation 1

Clinical correlation is essential for accurate interpretation, and when findings are equivocal or clinical suspicion is high, advanced imaging should not be delayed. 1