Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is obscuration of the left hemidiaphragm , though this is not significantly changed from ___ . There may be some increased atelectasis in the left lung base . There is new retrocardiac opacity suggesting pneumonia . The patient is status post median sternotomy . A prosthetic aortic valve is again noted . The cardiac silhouette is top normal in size , and unchanged compared with prior . The mediastinal contours are notable for surgical clips and calcification of the aortic knob . The pulmonary vasculature is normal .
    OUTPUT:
    
Chronic left basal opacity likely reflects atelectasis which may be slightly worse in the interval , with new retrocardiac opacity consistent with pneumonia . This change in the original read was discussed with Dr . ___ at 7 : 40 am by phone .