Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are reduced compared to the previous exam . This accentuates the size of the cardiac silhouette which is likely within normal limits . The aortic knob is calcified . There is crowding of bronchovascular structures but no pulmonary edema is present . Mediastinal and hilar contours otherwise are unremarkable . Patchy bibasilar airspace opacities could reflect atelectasis but infection can not be excluded . There is no pleural effusion or pneumothorax identified . Degenerative changes are seen within the imaged thoracolumbar spine .
    OUTPUT:
    
Low lung volumes with patchy bibasilar airspace opacities likely reflecting atelectasis but infection can not be excluded .