Diagnostic value of lung ultrasound versus chest CT in COVID-19

Lung ultrasound demonstrates a high diagnostic value in the assessment of lung diseases.

Aim. To determine the diagnostic accuracy of lung ultrasound compared to chest computed tomography (CT) in the diagnosis of lung changes in COVID-19.

Materials and methods. The retrospective study included 45 patients (28 men) aged 37 to 90 years who underwent polypositional lung ultrasound with an assessment of 14 zones. The study compared lung echograms with chest CT data in assessing the prevalence of the process and the nature of structural changes. The diagnostic accuracy, sensitivity, and specificity of lung ultrasound in comparison with CT scans were determined, 95% confidence intervals (CI) were calculated.

Results. In 44 patients (98%), CT revealed pathological changes with subpleural localization in both lungs. Of these, in 30 cases, the inflammation was limited only to the subpleural parts, and in 14 cases, the changes spread to the basal parts of the lungs, while ultrasound revealed changes at the depth of the lesion no more than 4 cm. The lesion of 10–11 zones according to lung ultrasound corresponds to CT 1–2 degrees, the lesion of 13–14 zones — CT 3–4 degrees. The sensitivity of ultrasound to detect lung changes of various types was ≥ 92%. The highest sensitivity of 97.9% (95% CI: 92.8–99.8%) was determined for small consolidations on the background of interstitial changes (degree 1A+, 1B+), which corresponded to “crazy-paving” pattern on CT. The specificity depended on the nature of the changes and varied from 46.7 to 70.0%. Diagnostic accuracy was ≥ 81%, the maximum values of 90.6% (95% CI: 85.6–94.2%) were obtained for moderate interstitial changes (grade 1A) corresponding to ground-glass opacity (type one) according to CT data.

Conclusion. The sensitivity of ultrasound to detect lung changes in COVID-19 is more than 90%. Lung ultrasound has some limitations: inability to determine the prevalence of the process clearly and identify centrally located areas of changes in the lung tissue.