First, the sensitivity of a diagnostic test can be greatly affected by the context in which it is used. The reader should consider the conditions in which such relatively low sensitivities were obtained (eg, a stressful examination in the ED, the patient immobilized on a vacuum mattress with no possible exploration of the posterior areas, the raised probability of concomitant thoracic lesions in the same patient, and possible subcutaneous emphysema). In addition, the physicians in charge of the patients and the ultrasound operators were asked to write their diagnoses according to a probability diagnostic scale prior to the thoracic CT scan. We then expressed the diagnostic performance of each modality in terms of its area under the receiver operating characteristic curve and not in terms of its sensitivity alone. To our knowledge, our study was the first to estimate and compare the areas under the receiver operating characteristic curves of thoracic ultrasonography after trauma.