What is the preferred imaging modality, High-Resolution Computed Tomography (HRCT) with or without contrast, for diagnosing pulmonary contusion?

CT Chest Without Contrast is the Preferred Imaging Modality for Pulmonary Contusion

CT chest without contrast is the recommended imaging modality for diagnosing and evaluating pulmonary contusion, as it provides optimal visualization of lung parenchyma and pleural abnormalities without the need for contrast enhancement. 1, 2

Rationale for Non-Contrast CT in Pulmonary Contusion

• CT of the chest is recommended for initial diagnosis of pulmonary contusion; the extent of contusion on CT correlates with the incidence and severity of complications 2
• Non-contrast CT provides optimal visualization of lung parenchyma and pleural abnormalities, which are the primary concerns in pulmonary contusion 1, 3
• CT chest without IV contrast is generally appropriate for evaluating traumatic lung injuries and is considered the reference standard for the noninvasive assessment of thoracic injury in patients with chest trauma 4
• Thoracic computed tomography is both highly sensitive in identifying pulmonary contusion and highly predictive of the need for subsequent mechanical ventilation 3
• High-resolution CT (HRCT) technique can be applied when more detailed evaluation of the lung parenchyma is needed, particularly for diffuse lung diseases 5

When Contrast May Be Considered

• CT chest with IV contrast may be appropriate when there is suspicion of vascular injuries accompanying the pulmonary contusion 4
• CTA chest with IV contrast is indicated when there is concern for active bleeding, contrast extravasation, or hemothorax 4
• In patients with blunt trauma and suspected pleural effusion, CT chest with IV contrast is regarded as the reference standard for identifying hemothorax and contrast extravasation 4
• Contrast-enhanced CT should be considered when there is suspicion of:
  • Vascular abnormalities 1
  • Bronchopleural fistula 1, 4
  • Need for pre-surgical planning 1

Clinical Approach to Imaging for Pulmonary Contusion

• Initial evaluation should begin with chest radiography, but it may underestimate the injury 2, 6
• CT chest without IV contrast should be performed when pulmonary contusion is suspected, especially in the context of significant blunt chest trauma 2, 3
• For patients with renal dysfunction, risk factors for contrast nephropathy, or known contrast allergy, non-contrast CT is particularly appropriate 4
• Short-term follow-up can be performed with conventional chest X-ray 2

Important Considerations and Potential Pitfalls

• Pulmonary contusion is characterized by dynamic development, making it difficult to recognize the actual extent of injury at an early stage 2
• The injury typically manifests within hours of trauma and usually resolves within approximately 7 days 3, 6
• Clinical symptoms, including respiratory distress with hypoxemia and hypercarbia, typically peak at about 72 hours after injury 3
• In pediatric patients, radiation exposure is a significant concern, so the indication for CT should be carefully considered 7
• Failing to evaluate for underlying lung pathology that may contribute to complications can be avoided by using appropriate CT protocols 1
• Using contrast unnecessarily when non-contrast CT is sufficient for most cases of pulmonary contusion should be avoided 1, 8

Alternative Imaging Modalities

• MRI is not commonly recommended as the initial imaging study for pulmonary contusion due to practical limitations, especially in potentially unstable trauma patients 4
• Ultrasound of the chest has limited utility for evaluating pulmonary contusion but may be useful for detecting associated pleural effusions or hemothorax 4