Purpose: The aim of our study was to assess the serial high-resolution CT findings and their correlation with the results of pulmonary function tests in patients with progressive systemic sclerosis (PSS) and interstitial pneumonia.
Method: The study included 40 patients with symptoms or signs of PSS and interstitial pneumonia, who underwent serial high-resolution CT scans (mean follow-up period 39 months). Seventeen patients simultaneously had serial pulmonary function tests (mean follow-up period 40 months). On high-resolution CT, the pattern and extent of parenchymal abnormalities were retrospectively analyzed. Serial changes on high-resolution CT were correlated with the changes of pulmonary function tests.
Results: On initial CT, areas of ground-glass opacity (mean +/- SD extent 17.7 +/- 12.3% in all patients), irregular linear opacity (4.4 +/- 4.4% in 36 patients), small nodules (3.9 +/- 12.5% in 28), consolidation (1.9 +/- 4.2% in 13), and honeycombing (1.9 +/- 3.8% in 12) were seen. The total disease extent (p = 0.042) and extents of ground-glass opacity (18.9 +/- 15.5%; p = 0.04) and honeycombing (5.0 +/- 7.2%; p = 0.002) increased significantly on follow-up CT. Both forced vital capacity (from 2.4 +/- 0.4 to 2.0 +/- 0.4 L; p = 0.002) and forced expiratory volume in 1 s (from 2.0 +/- 0.4 to 1.6 +/- 0.3 L; p = 0.013) decreased significantly on follow-up examination. The increase in the extent of honeycombing on CT correlated significantly with the decrease in diffusing capacity for carbon monoxide (r = -0.411, p = 0.049).
Conclusion: In patients with PSS and interstitial pneumonia, the overall extent of disease and extents of honeycombing and ground-glass opacity increase significantly on follow-up CT. Increase of honeycombing correlates well with decrease of diffusing capacity for carbon monoxide.