Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Study is somewhat limited due to patient rotation and the patient 's chin projecting over and obscuring the lung apices . Lung volumes are low . The heart remains mildly enlarged with a left ventricular predominance . The aorta is tortuous . There is no pulmonary vascular congestion . Mediastinal and hilar contours are stable . There has been interval improvement in aeration of the right lung base , but persistent patchy opacities are seen within the left lung base . No large pleural effusion is seen , but a small left pleural effusion can not be completely excluded . No pneumothorax . No acutely displaced fractures are seen . A remote right - sided rib fracture is noted .
    OUTPUT:
    
Patchy bibasilar airspace opacities , with interval improvement in aeration of the right lung base . Findings likely reflect atelectasis though infection or aspiration can not be completely excluded . No pneumothorax .