Utility of chest CT after a chest X-ray in patients presenting to the ED with non-traumatic thoracic emergencies

Chest radiography is the initial choice for thoracic imaging. However, the wide availability of computed tomography (CT) has led to a substantial increase in its use in the emergency department (ED). We evaluated the utility of chest CT after a chest X-ray in patients presenting to the ED with non-traumatic thoracic emergencies, and determined if the diagnosis and management decision changed after CT. The study enrolled 500 consecutive patients with both chest X-rays and CT who presented to the ED with non-traumatic complaints. Chest X-rays and CT images obtained within 12h before any definitive treatment were randomly evaluated in consensus by two radiologists blinded to the clinical information. The chest X-ray and CT image findings were concordant in 49.2% of the 500 patients and this concordance was negatively correlated with patient age. Leading diagnosis and management decisions based on the chest radiograph changed after CT in 35.4% of the study group and this finding was also correlated with age. In 55% of 205 patients, pneumonic infiltrations were undiagnosed with radiography. Pulmonary edema was the most specific (93.3%) and sensitive (85.4%) radiography finding. Posteroanterior chest radiographs taken in the upright position had higher concordance with CT than anteroposterior (AP) radiographs taken in the supine position. Chest CT may be an appropriate imaging choice in patients presenting to the ED for non-traumatic reasons, particularly for elderly patients and when the radiograph is taken with the AP technique in a supine position. •Findings of chest radiographs and CT images were concordant in 49.2% of 500 patients.•Leading diagnosis and management decisions changed after CT in 35.4% of patients.•In 55% of 205 patients, pneumonic infiltration was undiagnosed with radiography.•Pulmonary edema was the most specific and sensitive finding of radiography.