Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lungs are clear without focal consolidation , effusion , or edema . Cardiac silhouette is within normal limits . Enlargement of the left hilum is felt to be due to pulmonary artery enlargement . Chronic changes of the posterior left fourth and fifth ribs are noted . Small median sternotomy wires are noted .
    OUTPUT:
    
No acute cardiopulmonary process , no focal consolidation . Apparent enlargement of the pulmonary artery , involving the main and left . Correlate with patient 's history ( given remote prior sternotomy changes ) .