Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Low lung volumes are present , and when combined with supine technique , result in widening of the superior mediastinum . Heart size is likely unchanged . Streaky bibasilar opacities are more pronounced in the retrocardiac region , and could reflect areas of atelectasis though infection or aspiration is not completely excluded . No large pleural effusion or pneumothorax is present . There is no pulmonary vascular congestion . No acute osseous abnormality is identified .
    OUTPUT:
    
Low lung volumes and supine technique likely explain the mild superior mediastinal widening . Bibasilar streaky opacities may reflect atelectasis though infection or aspiration can not be excluded .