What is the interpretation and treatment for an abnormal chest X-ray (CXR)?

Sharing and Interpreting Chest X-Rays

When sharing a chest X-ray (CXR) for interpretation, you should provide clinical context including respiratory symptoms, vital signs (especially oxygen saturation and fever), relevant laboratory values (C-reactive protein, lactate dehydrogenase), and specific clinical concerns, as CXR findings must be correlated with clinical presentation for accurate diagnosis and management. 1

Essential Clinical Information to Include

When sharing a CXR, always provide:

• Respiratory symptoms: Presence or absence of cough, dyspnea, chest pain, or hemoptysis, as CXR has no diagnostic value in patients without respiratory signs or symptoms if a reliable medical history can be obtained 2
• Vital signs: Oxygen saturation, heart rate, blood pressure, and fever duration, as these correlate with radiographic severity 1
• Clinical suspicion: Specific concerns such as infection, cardiac disease, aortic pathology, or trauma guide interpretation priorities 3
• Relevant laboratory data: C-reactive protein and lactate dehydrogenase show significant positive correlation with CXR severity scores 1

Understanding CXR Limitations

CXR is a screening tool with significant limitations that must be recognized to avoid missed diagnoses:

• Sensitivity depends on lesion size and location: Small pulmonary nodules, ground-glass opacities, and lesions hidden behind the heart, mediastinum, or diaphragm are commonly missed 4
• Low sensitivity for specific pathologies: CXR detected only 28% of pulmonary metastatic disease compared to CT, and was normal in 49 of 166 confirmed acute respiratory infections on CT 4
• Interpreter-dependent variability: Detection rates vary significantly based on radiologist skill and experience 4

When Additional Imaging is Required

Cross-sectional imaging with CT should be obtained when:

• Aortic pathology is suspected: Widened mediastinum, aortic tortuosity, or mass effect on para-aortic structures on CXR requires immediate CT angiography or transesophageal echocardiography 3
• High clinical suspicion despite normal CXR: Greater than one-third of patients had significant findings on CT after normal screening chest radiograph 4
• Pulmonary hypertension evaluation: CXR is insensitive for mild disease; echocardiography is the screening test of choice, with CT or MRI for definitive characterization 3
• Suspected tuberculosis with negative smears: CT provides superior detail for cavitation and disease extent, which impacts treatment duration 3

Common Pitfalls to Avoid

• Do not rely on CXR alone for excluding serious pathology: Up to 34% of chest radiographs were unremarkable in patients with CT-proven bronchiectasis 4
• Do not delay definitive imaging in unstable patients: In suspected aortic dissection, bedside echocardiography or immediate CT angiography takes priority over CXR 3, 5
• Do not use CXR for cancer screening: No randomized controlled trials demonstrate mortality reduction from CXR screening for lung cancer 4
• Avoid routine post-procedure CXRs: Clinical symptoms such as respiratory or hemodynamic changes are reliable predictors of complications requiring intervention 3

Specific Clinical Scenarios

For suspected infection without respiratory symptoms:

• CXR has no diagnostic value if reliable history can be obtained; focus clinical assessment on localizing signs 2

For trauma evaluation:

• Portable AP CXR screens for life-threatening findings (tension pneumothorax, mediastinal injury) but has lower sensitivity for pneumothorax, hemothorax, lung contusions, and rib fractures compared to CT 3
• Approximately 40% of patients with "normal" chest radiograph had injuries on CT 3

For suspected thoracic aortic aneurysm:

• CXR findings (widened mediastinum, aortic widening) trigger need for CT angiography or echocardiography, as CXR is neither sensitive nor specific 3
• Aneurysms >5 cm diameter or increasing >0.5 cm per year require intervention evaluation 3

For post-cardiac surgery monitoring:

• Routine daily CXRs have limited diagnostic value; order based on clinical signs and symptoms to reduce radiation exposure and costs 3