What does this mean... Cardiac silhoutte within normal limits. Hilary and mediastinal structures appear unremarkable. linear streaks both lung bases which may represent linear scarring or less likely linear atelectasis. No consolidation or effusion seen. The osteosarcoma structures appear grossly intact. Bibasilar linear streak scar versus atelectasis. Clinical correlation. No evidence of acute cardiopulmonary disease, communicable disease or tuberculosis.