Accuracy of lung ultrasound for the diagnosis of consolidations when compared to chest computed tomography

Objectives: Despite emerging evidences on the clinical usefulness of lung ultrasound (LUS), international guidelines still do not recommend the use of sonography for the diagnosis of pneumonia. Our study assesses the accuracy of LUS for the diagnosis of lung consolidations when compared to chest computed tomography (CT).

Methods: This was a prospective study on an emergency department population complaining of respiratory symptoms of unexplained origin. All patients who had a chest CT scan performed for clinical reasons were consecutively recruited. LUS was targeted to evaluate lung consolidations with the morphologic characteristics of pneumonia, and then compared to CT.

Results: We analyzed 285 patients. CT was positive for at least one consolidation in 87 patients. LUS was feasible in all patients and in 81 showed at least one consolidation, with a good inter-observer agreement (k = 0.83), sensitivity 82.8% (95% CI 73.2%-90%) and specificity 95.5% (95% CI 91.5%-97.9%). Sensitivity raised to 91.7% (95% CI 61.5%-98.6%) and specificity to 97.4% (95% CI 86.5%-99.6%) in patients complaining of pleuritic chest pain. In a subgroup of 190 patients who underwent also chest radiography (CXR), the sensitivity of LUS (81.4%, 95% CI 70.7%-89.7%) was significantly superior to CXR (64.3%, 95% CI 51.9%-75.4%) (P<.05), whereas specificity remained similar (94.2%, 95% CI 88.4%-97.6% vs. 90%, 95% CI 83.2%-94.7%).

Conclusions: LUS represents a reliable diagnostic tool, alternative to CXR, for the bedside diagnosis of lung consolidations in patients with respiratory complains.