Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Left - sided pacemaker device is again noted with leads terminating in the right atrium and right ventricle , unchanged . Mild to moderate cardiomegaly is again noted . Mediastinal and hilar contours are unchanged . Low lung volumes persist . There is no pulmonary vascular congestion . Patchy bibasilar opacities likely reflect areas of atelectasis . No pleural effusion or pneumothorax is present . No acute osseous abnormalities identified .
    OUTPUT:
    
Low lung volumes with probable bibasilar atelectasis .