Should I order a chest Computed Tomography (CT) scan for this patient?

Chest CT Ordering in Clinical Practice

Chest CT scanning should be ordered selectively based on specific clinical indications rather than routinely, with contrast-enhanced CT being preferred when evaluating for vascular injuries, metastatic disease, or lymphadenopathy.

Key Considerations for Chest CT Ordering

Clinical Scenarios Where Chest CT is Recommended:

• Suspected thoracic injuries after trauma:

  • CT chest with IV contrast is the preferred imaging for evaluating suspected chest trauma, as it is more sensitive and specific than conventional radiographs 1
  • For blunt trauma with concern for chest injury, contrast-enhanced CT can detect vascular injuries that noncontrast CT might miss 1

• Malignancy evaluation:

  • For patients with known or suspected lung cancer who are eligible for treatment, a CT scan of the chest with contrast is recommended 1
  • In patients with muscle-invasive bladder cancer (MIBC), chest CT is recommended for pulmonary evaluation 1
  • CT chest with IV contrast is preferred over CT chest without IV contrast when evaluating for metastatic disease and lymphadenopathy 1

• Pleural effusion workup:

  • In patients with suspected malignant pleural effusion, CT chest with IV contrast is recommended 1
  • Acquiring the CT scan 60 seconds after contrast bolus improves visualization of pleural abnormalities associated with malignancy 1

When Chest CT is Not Recommended:

• Routine screening after minor trauma with normal chest radiograph:

  • In the NEXUS Chest CT trial, blunt trauma patients without an abnormal chest radiograph and meeting 6 clinical criteria could avoid unnecessary chest CT (sensitivity 99.2%) 1
  • For non-muscle invasive bladder cancer (NMIBC), chest CT may not be necessary unless there is upstaging during follow-up 1

• Perifissural/subpleural nodules with typical morphology:

  • Follow-up CT is generally not recommended for perifissural/juxtapleural nodules with typical morphology consistent with intrapulmonary lymph nodes 2
  • No follow-up is needed for typical perifissural or subpleural nodules <10mm with homogeneous, smooth, solid appearance and lentiform or triangular shape 2

Contrast vs. Non-Contrast CT

• Contrast-enhanced CT is preferred when:

  • Evaluating for vascular injuries in trauma 1
  • Assessing for metastatic disease and lymphadenopathy 1
  • Evaluating suspected malignant pleural effusion 1

• Non-contrast CT can detect:

  • Rib fractures, pneumothorax, hemothorax, and pulmonary contusion 1
  • However, it has lower sensitivity for detecting vascular injuries 1

Radiation Considerations

• CT doses are higher than conventional radiography but still 10-100 times lower than dose levels reported to increase cancer risk 3
• Thin sections (≤1.5mm) should be used to accurately characterize nodules 2
• Unnecessary medical tests should always be avoided to minimize radiation exposure 3

Common Pitfalls to Avoid

1. Ordering chest CT before reviewing chest radiograph results:

   • In one study, 50.3% of cases had a second imaging modality ordered before final report availability of the first exam 4
   • This represents inefficient resource usage that could be addressed with targeted technology solutions 4

2. Underestimating radiation exposure:

   • More than 90% of physicians either did not know or significantly underestimated the radiation associated with CT (equivalent to 100 PA chest radiographs) 5

3. Failing to recognize growth in previously stable nodules:

   • Documented growth in a previously stable nodule warrants further evaluation 2
   • Inadequate imaging technique can lead to mischaracterization of nodules 2

By following these evidence-based guidelines, clinicians can make more informed decisions about when to order chest CT scans, ensuring appropriate resource utilization while maintaining high-quality patient care.