Utility of lung ultrasound in assessing severity of interstitial lung diseases: correlation with high-resolution computed tomography and spirometry findings.

Abstract

Interstitial lung diseases (ILDs) constitute a diverse category of diffuse parenchymal lung disorders whose diagnosis and monitoring are challenging due to complex clinic-radiological profiles and the risks of serial high-resolution computed tomography (HRCT). Lung ultrasound (LUS) has potential to become an easily available, non-ionizing substitute, though its comparative performance against HRCT and spirometry in severity assessment has been inadequately studied. We conducted a cross-sectional study of 52 adult ILD outpatients enrolled over one year, excluding those with cardiac failure, pulmonary tuberculosis, neoplasia, pregnancy, or acute ILD exacerbation. Each patient underwent LUS using a linear probe to determine total B-line score, total positive chest areas with ≥5 B-lines, and pleural line abnormalities; HRCT was scored by the Warrick system, and spirometry measured forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). There was a substantial correlation (r=0.75, p<0.001) between the Total B-line score (mean 39.3±15.3) and the Warrick score (11.94±5.09) and the Warrick score and total positive chest area score (r=0.77, p<0.001). Notable unfavorable associations were observed between LUS B-line score and FVC (r=-0.75, p=0.00) and FEV1 (r=-0.73, p=0.00). LUS demonstrated sensitivity of 97.9% and diagnostic accuracy of 94.2% compared with HRCT, though specificity was moderate (60%). These findings indicate that LUS closely mirrors HRCT and spirometry in assessing ILD severity. Given its high sensitivity, safety profile, and accessibility, LUS may serve as a valuable adjunct for routine evaluation and follow-up of ILD patients, particularly where repeated HRCT is impractical. Further large-scale, prospective studies are required to validate standardized LUS scoring and establish its role in guiding ILD management.