Is a CT (Computed Tomography) chest with or without contrast more appropriate for assessing a patient involved in a motor vehicle collision?

CT Chest with IV Contrast is Superior for Motor Vehicle Collision Assessment

For motor vehicle collision trauma, CT chest WITH intravenous contrast should be performed, not noncontrast CT, as contrast-enhanced imaging has significantly greater sensitivity for detecting life-threatening vascular injuries and visceral organ damage that directly impact mortality. 1

Why Contrast is Not Redundant—It's Essential

Vascular Injury Detection

• Noncontrast CT has lower sensitivity for detecting vascular injuries, which are critical determinants of mortality in blunt chest trauma 1, 2
• Contrast-enhanced CT accurately detects active hemorrhage with 94.1% sensitivity and 97.6% negative predictive value, compared to angiography as the gold standard 3
• Aortic and major vessel injuries require arterial phase contrast imaging for detection—these injuries are potentially lethal and cannot be reliably excluded without contrast 1

Comprehensive Injury Assessment

• CT chest with IV contrast has greater sensitivity for detecting visceral organ and vascular injury compared with noncontrast CT, and should be primarily considered unless absolutely contraindicated 1
• Noncontrast CT can detect rib fractures, pneumothorax, hemothorax, and pulmonary contusion, but misses critical vascular pathology that determines need for surgical or endovascular intervention 1
• Contrast-enhanced CT is the preferred imaging workup of suspected chest trauma regardless of other considerations 1

Clinical Algorithm for MVC Chest Imaging

Initial Screening

• Begin with portable AP chest radiograph to screen for immediately life-threatening findings (tension pneumothorax, significant mediastinal injury) and confirm line placement 1, 4
• If chest X-ray is abnormal in trauma setting, proceed directly to CT chest with IV contrast, as these patients have clinically significant rates of major injury on CT 1, 4, 2

Definitive Imaging Decision

• For hemodynamically stable MVC patients, obtain CT chest with IV contrast as the definitive study 1, 2
• High-velocity mechanisms (>35 mph collision, rollover, ejection) warrant whole-body CT with contrast (chest/abdomen/pelvis) 1
• Arterial phase imaging is particularly important when there is concern for aortic or major vessel injury based on mechanism 1

When to Consider Noncontrast CT

• Absolute contraindications to IV contrast (severe contrast allergy, severe renal dysfunction) are the ONLY scenarios where noncontrast CT is acceptable 1
• Even in these rare cases, recognize that diagnostic sensitivity is compromised 1, 5

Critical Evidence Supporting Contrast Use

Mortality and Intervention Prediction

• Contrast-enhanced CT had 92.6% sensitivity and 91.2% negative predictive value for predicting need for surgical or endovascular intervention in torso trauma 3
• CT with IV contrast identified injuries in 54% of blunt chest trauma patients, with no missed blunt aortic injuries when contrast was used 6
• The superiority of CT over chest radiography in diagnosing chest trauma is well-documented, with MDCT reducing imaging time to seconds while providing comprehensive vascular assessment 7

Common Pitfalls to Avoid

Don't Assume Noncontrast is "Good Enough"

• Never order noncontrast CT when vascular assessment is needed—this delays definitive diagnosis and may miss life-threatening injuries 2
• Chest radiographs miss 40% of injuries detected on CT, including half of all pneumothoraces, and cannot assess vascular integrity 2
• Hemothorax or hemopericardium on noncontrast imaging warrants immediate contrast-enhanced study to identify bleeding source and guide intervention 2

Recognize Mechanism-Based Risk

• Motor vehicle collisions have high rates of thoracic vascular injury due to deceleration forces 8
• Mediastinal hemorrhage on any imaging modality mandates contrast-enhanced evaluation for great vessel injury 8
• Don't rely on hemodynamic stability alone—occult vascular injuries can present in stable patients 3, 6

Protocol Considerations

• Standard trauma CT with IV contrast (not specialized CTA) is sufficient for initial assessment and may be preferable for whole-body imaging with single contrast injection 6
• Contrast-enhanced CT of chest, abdomen, and pelvis should be primarily considered unless absolutely contraindicated in high-energy MVC 1