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

OBJECTIVE. The purpose of our study was to identify CT patterns of pulmonar y fibrosis in patients with sarcoidosis and to correlate these patterns wit h pulmonary function tests. MATERIALS AND METHODS. We conducted a retrospective review of CT scans of 8 0 patients with proven sarcoidosis and evidence of fibrotic changes on ches t radiographs. RESULTS. Three main CT patterns were identified: bronchial distortion (n = 38, 47%), mainly central; honeycombing (n = 23, 29%), mainly peripheral; an d linear (n = 19, 24%), mainly diffuse. In most cases, a pattern was clearl y identified as shown by the good agreement between observers (kappa = 0.87 ). Nodules were significantly associated with the linear (87%) and distorte d (71%) patterns, but not with the honeycomb pattern (35%). The honeycomb p attern was most often associated with restriction and decreased lung diffus ing capacity for carbon monoxide. Patients with bronchial distortion had lo wer expiratory airflow rates. The linear pattern was generally associated w ith 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 re flect different distributions of fibrotic lesions in the lung with differen t functional pulmonary impairments. The persistence of active pulmonary les ions suggested by the presence of nodular lesions was often associated with linear and distorted patterns.