Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear stable . Lung volumes are low . There is no pleural effusion or pneumothorax . There is new retrocardiac opacification which is fairly streaky in nature . Elsewhere , the lungs remain clear . There is very mild S shaped curvature to the visualized thoracolumbar spine .
    OUTPUT:
    
New left lower lobe opacity with morphology more suggestive of atelectasis than pneumonia although infection of lower airways or bronchopneumonia is not excluded .