Is a CT (Computed Tomography) scan with or without contrast indicated for patients with chest wounds?

From the Guidelines

A CT scan with contrast is the preferred imaging modality for patients with chest wounds, particularly when there is suspicion of vascular injury, mediastinal involvement, or deep tissue damage, as it offers a high negative predictive value and can identify vascular injuries such as pseudoaneurysms, intimal flaps, filling defects, or contrast extravasation 1. The decision to use contrast-enhanced CT is based on the specific clinical scenario and patient factors, with contrast-enhanced CT being preferred for penetrating chest trauma to evaluate for vascular injuries, while non-contrast CT may be sufficient for simple blunt trauma with low suspicion of vascular involvement. Some key points to consider when deciding between CT with or without contrast for chest wounds include:

• The ability of contrast-enhanced CT to highlight vascular structures and active bleeding, providing crucial information for treatment planning in chest trauma cases 1
• The lower sensitivity of non-contrast CT for detecting vascular injuries, which may lead to missed diagnoses and delayed treatment 1
• The importance of considering patient factors, such as renal impairment, previous contrast reactions, and untreated hyperthyroidism, when deciding whether to use contrast-enhanced CT 1
• The potential benefits of alternative imaging modalities, such as ultrasound or MRI, for patients who cannot receive contrast 1 In terms of specific guidelines, the American College of Radiology recommends the use of contrast-enhanced CT for evaluating suspected chest trauma, particularly when there is suspicion of vascular injury or mediastinal involvement 1. Overall, the use of contrast-enhanced CT for chest wounds is supported by the most recent and highest quality evidence, and should be considered the preferred imaging modality for patients with suspected vascular injury, mediastinal involvement, or deep tissue damage 1.

From the FDA Drug Label

The decision to employ contrast enhancement, which may be associated with risk and increased radiation exposure, should be based upon a careful evaluation of clinical, other radiological, and unenhanced CT findings. Contrast enhancement appears to be greatest immediately after bolus administration (15 seconds to 120 seconds). Utilization of a continuous scanning technique (ie, dynamic CT scanning) may improve enhancement and diagnostic assessment of tumor and other lesions such as abscess, occasionally revealing unsuspected or more extensive disease

The use of CT scans with or without contrast for patients with chest wounds should be determined on a case-by-case basis, considering the individual's clinical and radiological findings.

• The decision to use contrast enhancement should be based on a careful evaluation of the patient's condition.
• Dynamic CT scanning may be useful in improving diagnostic assessment of certain lesions. 2

From the Research

Indications for CT Scan in Chest Wounds

• A CT scan with or without contrast is indicated for patients with chest wounds, especially in cases of blunt thoracic trauma, to identify critical injuries and guide further management 3, 4, 5, 6.
• The use of contrast-enhanced CT scans can help detect subtle and obvious aortic tears, as well as other injuries such as pulmonary lacerations, pneumothoraces, and diaphragmatic tears 5, 6.

Comparison with Chest X-ray

• Chest X-ray is a valuable initial diagnostic test, but CT scans have higher sensitivity and can provide more detailed information about the extent of injuries 3, 4.
• In cases where chest X-ray is normal, CT scans may not be necessary, but they can still provide useful information in cases of thoracoabdominal wounds or suspected diaphragmatic injury 4.

Use of Contrast Agents

• The choice of contrast agent can affect the quality of vascular imaging on CT scans, with iso-osmolar contrast agents such as iodixanol providing equal vascular enhancement compared to hyperosmolar contrast agents like iohexol 7.
• The use of contrast agents can help improve the detection of vascular injuries, but careful attention to technique and potential pitfalls is necessary to ensure accurate diagnosis 6.

Specific Injuries

• CT scans can be useful in detecting specific injuries such as:
  • Aortic injuries: contrast-enhanced CT scans can help detect subtle and obvious aortic tears 5, 6.
  • Diaphragmatic injuries: targeted spiral CT with sagittal and coronal reformatted images can increase sensitivity and specificity in detecting diaphragmatic injury 6.
  • Pulmonary lacerations and pneumothoraces: CT scans can provide more detailed information about the extent of these injuries compared to chest X-ray 6.