Sarcoidosis with pulmonary fibrosis: CT patterns and correlation with pulmonary function

OBJECTIVE. The purpose of our study was to identify CT patterns of pulmonary fibrosis in patients with sarcoidosis and to correlate these patterns with pulmonary function tests. MATERIALS AND METHODS. We conducted a retrospective review of CT scans of 80 patients with proven sarcoidosis and evidence of fibrotic changes on chest radiographs. RESULTS. Three main CT patterns were identified: bronchial distortion (n = 38, 47%), mainly central; honeycombing (n = 23, 29%), mainly peripheral; and linear (n = 19, 24%), mainly diffuse. In most cases, a pattern was clearly identified as shown by the good agreement between observers (kappa = 0.87). Nodules were significantly associated with the linear (87%) and distorted (71%) patterns, but not with the honeycomb pattern (35%). The honeycomb pattern was most often associated with restriction and decreased lung diffusing capacity for carbon monoxide. Patients with bronchial distortion had lower expiratory airflow rates. The linear pattern was generally associated with the least functional impairment. CONCLUSION. CT may be a useful tool for defining subgroups of patients with fibrotic pulmonary sarcoidosis. CT reveals three main patterns that may reflect different distributions of fibrotic lesions in the lung with different functional pulmonary impairments. The persistence of active pulmonary lesions suggested by the presence of nodular lesions was often associated with linear and distorted patterns.