Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There are low lung volumes with bronchovascular crowding at the lung bases . Ill - defined densities noted particularly in the retrocardiac left lower lobe . No further consolidation or edema is evident . The mediastinum is unremarkable . The cardiac silhouette is within normal limits for size . No effusion or pneumothorax is noted . The visualized osseous structures are unremarkable .
    OUTPUT:
    
Density at the lung bases , particularly in the left lower lobe is presumed atelectasis given volume loss . However , an early developing pneumonia can not be entirely excluded . Repeat with improved depth of inspiration would be helpful , otherwise empiric treatment with short interval followup .