Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A frontal upright view of the chest was obtained portably . Low lung volumes result in bronchovascular crowding . Increased density at the left lung base is unchanged from ___ . A small focus of linear atelectasis is seen in the lingula . The remainder of the lungs is clear . There is no substantial pleural effusion . No pneumothorax . Heart size is normal . The mediastinal silhouette and hilar contours are normal allowing for lung volumes . No upper abdominal or osseous abnormality is identified .
    OUTPUT:
    
Mildly increased opacity at the left lung base is likely atelectasis , but could represent aspiration or pneumonia in the appropriate clinical setting .