Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single semi-erect frontal view of the chest was obtained . The right lung is clear . Patchy left base opacity most likely represents atelectasis , though underlying aspiration is not entirely excluded . No pleural effusion or pneumothorax is seen . No pulmonary edema is seen . The cardiac silhouette is top normal . The aorta is calcified and tortuous .
    OUTPUT:
    
Patchy left base opacity most likely represents atelectasis , although underlying aspiration not excluded .