Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views chest demonstrate decreased lung volumes . There is dense left retrocardiac opacity which may represent atelectasis , infection or aspiration . There is blunting of the left costophrenic angle which may represent a small pleural effusion . No pneumothorax is identified . The right hilum is prominent but stable compared to multiple prior radiographs . The aorta is ectatic and tortuous and the heart is mildly enlarged . There are degenerative changes in the thoracic spine .
    OUTPUT:
    
1 . Left retrocardiac opacity could represent atelectasis , infection or aspiration . 2 . The left costophrenic angle is blunted . A small left pleural effusion is not excluded .