Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is mildly enlarged . Mediastinal and hilar contours are unremarkable . Atherosclerotic calcifications are noted at the aortic knob . Pulmonary vasculature is normal . No focal consolidation , pleural effusion or pneumothorax is present . Lung volumes are slightly low with mild patchy opacity noted in the left lung base . No acute osseous abnormalities visualized .
    OUTPUT:
    
Low lung volumes . Mild patchy opacity in the left lung base may reflect residual pneumonia or atelectasis .