Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Linear left basilar opacity is likely due to atelectasis given low lung volumes on the current exam . Calcific density again projects over the left upper lung laterally . The lungs are otherwise grossly unremarkable . The cardiomediastinal silhouette is stable . Median sternotomy wires and mediastinal clips again noted .
    OUTPUT:
    
Left base opacity likely due to atelectasis given low lung volumes . No central venous line identified .