Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Evaluation on the lateral radiograph is limited by positioning . Lung volumes are somewhat low , causing some bronchovascular crowding . No significant pleural effusion is seen . Patchy opacity in the posterior lower lobe lobe likely represents atelectasis . The heart size is normal .
    OUTPUT:
    
Patchy left basilar opacity , probably due to atelectasis .