From the Guidelines
Contrast Computed Tomography (CT) is not the primary imaging modality for diagnosing fat embolism syndrome (FES), and non-contrast CT of the chest is typically preferred. For suspected fat embolism, the following steps can be taken:
- Perform a non-contrast chest CT
- Look for characteristic ground-glass opacities in a geographic distribution
- These opacities are often bilateral and patchy, predominantly in the upper lobes Contrast is usually not necessary because:
- The hallmark findings of FES are visible on non-contrast scans 1
- Contrast may obscure subtle ground-glass opacities
- There's a potential risk of exacerbating respiratory distress in already compromised patients If contrast CT is performed for other reasons, be aware that:
- It may still show the typical ground-glass opacities
- Contrast enhancement can help differentiate between vascular and alveolar filling In cases where pulmonary embolism is also suspected, a CT pulmonary angiogram (CTPA) with contrast may be considered, but this is not specific for fat embolism diagnosis 1. Remember that CT findings alone are not diagnostic of FES, and clinical correlation is essential, as the condition is characterized by altered mental status, respiratory distress, and petechial rash occurring typically 12–36 hours after injury 1. Other supportive tests like brain MRI for cerebral involvement may be necessary in some cases.
From the Research
Role of Contrast Computed Tomography (CT) in Diagnosing Fat Embolism
- The diagnosis of fat embolism syndrome (FES) relies on a combination of clinical symptoms and radiological features, with computed tomography (CT) playing a crucial role in identifying characteristic imaging findings 2, 3, 4, 5.
- CT findings suggestive of FES include diffuse, well-demarcated ground glass opacities, ill-defined centrilobular nodules, septal thickening, and patchy consolidation on bilateral lungs 2, 3, 4, 5.
- The presence of these imaging findings in a hypoxic patient with recent trauma or orthopedic surgery can help achieve the correct diagnosis of FES 2, 3.
- While non-contrast CT scans can be useful in evaluating vascular structures and identifying clues to vascular disorders, the use of contrast CT is not explicitly mentioned in the provided studies as a necessary or preferred method for diagnosing FES 6.
- The characteristic imaging findings on chest CT, combined with clinical manifestations and laboratory tests, can confirm the diagnosis of FES and guide treatment 3.