Fig. 2From: Serum KL-6 levels reflect the severity of interstitial lung disease associated with connective tissue diseaseSerum KL-6 levels of ILD patients according to semiquantitative CT grades. CT, computed tomography; grade 1, 0–25% involvement of ILD on chest CT; grade 2, 26–50%; grade 3, 51–75%; grade 4, 76–100%Back to article page