The usefulness of transthoracic ultrasound in the evaluation of lung diseases has been highlighted in the past decades. The aim of our study is to determine the diagnostic value of lung ultrasound in the detection of interstitial pulmonary fibrosis in patients with a rheumatic disease. Furthermore, we studied the possible correlation between the underlying disease and the frequency of pathological ultrasound findings.
A sample of 45 consecutive patients with RA (n=25), SSc (n=14) and SLE (n=6) and 40 healthy volunteers were enrolled into the study. Every study patient underwent both, lung sonography and HRCT. The following ultrasound findings were documented in each study patient: B- lines, subpleural nodes and irregularities of the pleura. HRCT was analysed by an experienced radiologist blind to sonography findings.
Twenty-eight percent of the RA cohort, 64% of the SSc patients and four out of 6 SLE patients showed ILD on HRCT. Pathological ultrasound patterns were significant more frequent in the ILD group than in the non-ILD group (comet tail artifacts/B-pattern: 100% vs. 12%, p<0.001; subpleural nodes: 55 % vs. 17%, p=0.006; thickenings of the pleural line: 95% vs. 12.5%, p<0.001). Subpleural nodes were present in 100% of the RA patients vs. 22% the SSc patients (p=0.003) and 50% of the SLE patients (p=0.049) with ILD. An irregular pleural line>3 mm was documented in 100% of SSC and SLE patients with ILD, vs. 86% of ILD patients suffering from RA (p=ns).
Transthoracic ultrasound of the lung might be a sensitive non-invasive tool to observe early stage interstitial lung disease in rheumatic diseases.