From the Guidelines
For diagnosing fat embolism, chest CT is the recommended first-line imaging modality, as it can detect small vessel occlusions and subtle parenchymal changes that occur in fat embolism syndrome 1. Key imaging findings to look for include:
- Bilateral ground-glass opacities
- Nodular or patchy consolidations
- Interlobular septal thickening
- Centrilobular nodules These findings typically have a geographic distribution and are more prominent in the upper lobes and peripheral lung regions. While chest X-ray can show diffuse bilateral infiltrates, it is less sensitive and specific than CT. MRI of the brain may be considered if neurological symptoms are present, as it can detect cerebral fat emboli 1. The rationale for using CT is its ability to detect early changes in fat embolism syndrome, which can aid in early diagnosis and management. It's also important to note that imaging findings may lag behind clinical presentation by 12-24 hours, so repeat imaging may be necessary if initial scans are negative but clinical suspicion remains high. In certain settings, ventilation and perfusion scans, as well as MR angiography, can be useful in diagnosing fat embolism, but chest CT remains the primary modality due to its high sensitivity and specificity 1.
From the Research
Imaging Modalities for Diagnosing Fat Embolism
The following imaging modalities are used to diagnose fat embolism (fat embolus):
- Computed Tomography (CT) scans, particularly high-resolution CT (HRCT) and chest CT 2, 3, 4, 5, 6
- Chest radiographs 2
CT Findings in Fat Embolism Syndrome
CT findings in fat embolism syndrome include:
- Ground-glass opacities 2, 3, 4, 5, 6
- Consolidations, often with gravity-dependent distribution 2, 6
- Nodules, including centrilobular nodules and random nodular patterns 3, 4, 5, 6
- Septal thickening, including smooth septal thickening and thickening of the bronchial wall 4, 6
- Patchy distribution of opacities, resulting in a geographic appearance 5
- Lobular ground-glass opacities and lobular consolidations 6
- Areas of crazy paving 6
Diagnostic Criteria
The diagnosis of fat embolism syndrome is often based on a combination of clinical criteria, including the Gurd and Wilson Criteria, and characteristic radiological features on CT scans 3, 4, 6. However, there is currently no gold standard diagnostic test for fat embolism syndrome, and further investigation is needed to explore new diagnostic criteria involving pulmonary radiological features 4.