Should a CT scan with or without IV contrast be used to evaluate for a fracture?

From the Guidelines

For detecting fractures, a CT scan without IV contrast is the preferred initial imaging study. This recommendation is based on the most recent and highest quality evidence available, which suggests that IV contrast does not add significant value to the detection of fractures and may even obscure subtle fracture lines in some cases 1. The natural density difference between bone and surrounding soft tissues provides sufficient contrast to identify fracture lines, displacements, and bone fragments, making non-contrast CT scans the standard approach for fracture detection.

Key Points to Consider

• Non-contrast CT scans clearly show the bony anatomy without the potential risks associated with contrast agents, such as allergic reactions or kidney problems.
• Contrast material does not enhance bone visualization and may actually obscure subtle fracture lines in some cases.
• CT without IV contrast is commonly used to exclude or confirm suspected wrist fractures when initial radiographs are equivocal 1.
• MRI is an alternative to CT for detecting fractures, especially when there is a high clinical suspicion for fracture and initial radiographs are normal, but it is more sensitive to soft-tissue injuries and bone bruises than CT 1.

Clinical Scenario Considerations

• If there is concern about associated soft tissue injuries, vascular damage, or if the clinical situation involves potential complications beyond the fracture itself (such as tumor involvement or infection), then a contrast-enhanced CT or MRI might be considered as a supplementary study.
• The decision should be made based on the specific clinical scenario, but for the primary purpose of fracture detection, a non-contrast CT scan is the standard approach.
• CT is useful in diagnosing injuries that are difficult to recognize on radiographs, such as carpometacarpal joint fracture dislocations, but it is usually not indicated for metacarpal and digital fractures 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. 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 A vascularized lesion is characterized by an increase in CT number in the few minutes after a bolus of intravascular contrast agent; it may be malignant, benign, or normal tissue, but would probably not be a cyst, hematoma, or other nonvascular lesion When looking for a fracture, a CT without IV contrast should be performed, as the use of contrast is not directly indicated for this purpose and may be associated with risk and increased radiation exposure 2.

From the Research

CT Scan with IV Contrast for Fracture Detection

• When looking for a fracture, the decision to perform a CT scan with or without IV contrast depends on various factors, including the patient's condition and the suspected type of injury 3.
• The use of IV contrast can improve the sensitivity and specificity of injury detection in CT scans, as recommended by the American College of Surgeons and American College of Radiology 3.
• However, the risk of contrast-induced nephropathy (CIN) should be considered, particularly in patients with preexisting diabetes or high Injury Severity Score (ISS) 4.

Risks and Benefits of IV Contrast

• The incidence of CIN in blunt trauma patients is relatively low, with a study showing a 4% rate of CIN and 1% rate of continued renal impairment on discharge 4.
• In pediatric trauma patients, IV contrast is not associated with the development of acute kidney injury (AKI) 5.
• Immediate complications from IV contrast administration are rare, with a study showing a 0.8% rate of minor complications and no severe complications 6.

Diagnostic Accuracy and Clinical Impact

• The inclusion of lower extremity CT angiography (CTA) as part of a whole-body CT (WBCT) imaging exam for trauma can help identify vascular injuries that may be associated with fractures 7.
• Physical exam findings may be insufficient to diagnose vascular injuries, highlighting the importance of imaging studies in trauma patients 7.
• The use of IV contrast can help improve diagnostic accuracy and clinical outcomes in trauma patients, particularly in cases where vascular injuries are suspected 3, 7.