Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low with secondary bronchovascular crowding . There is retrocardiac opacity , more conspicuous on the current exam , potentially atelectasis . Cardiac silhouette grossly stable given technique . No acute osseous abnormalities .
    OUTPUT:
    
Low lung volumes which likely account for retrocardiac opacity , likely atelectasis . No definite acute cardiopulmonary process .