Written by Clay Smith
Ultralow-dose chest CT (ULCT) had perfect diagnostic accuracy for minor traumatic injury to the chest. It was superior to plain CXR and delivered the same, or in several cases, a lower radiation dose.
Why does this matter?
We often obtain a CXR in patients with blunt thoracic trauma as a screening tool. But as CT technology improves, lower-dose techniques may more accurately detect injuries with the same or lower radiation dose than an x-ray. Is that the case here?
CT vs. x-ray = same radiation dose? Yup…
This was a comparison of patients with chest trauma that were hemodynamically stable and had traditional CXR +/- rib series and ULCT. CT was done with a 64 slice scanner without contrast, with iterative reconstruction (which reduces the “noise” from a lower dose scan). A reference CT, with a 1-2 mSv dose, was also done and read by the radiologists in real time as the gold standard. ULCT performed perfectly, with sensitivity 100%, specificity 100% for detecting all patients with at least one finding on reference CT, with no false positives. Plain x-ray had sensitivity 79%, specificity 89%. The radiation dose of ULCT was the same or lower than plain x-ray. ULCT is more expensive than x-ray. It also may or may not change management to find a small pneumothorax, hemothorax, or a couple rib fractures, but it depends. Might it be best to use ULCT instead of CXR in patients for whom we want to screen but not do a full trauma CT chest?
Here are two example images from the supplemental material.
Minor Blunt Thoracic Trauma in the Emergency Department: Sensitivity and Specificity of Chest Ultralow-Dose Computed Tomography Compared With Conventional Radiography. Ann Emerg Med. 2019 Jun;73(6):665-670. doi: 10.1016/j.annemergmed.2018.11.012. Epub 2019 Jan 18.
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