Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Opacity seen in at the left base laterally which may be due to atelectasis . Elsewhere , the lungs are clear given relatively low lung volumes . Cardiac silhouette is top - normal based on technique . Tortuosity of the descending thoracic aorta is noted . Radiopaque densities project over the left upper quadrant , incompletely assessed .
    OUTPUT:
    
No definite acute cardiopulmonary process .