Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is mild - to - moderate cardiomegaly . The thoracic aorta is tortuous . There is a retrocardiac opacity which could represent atelectasis or pneumonia in the correct clinical setting . The right lung is grossly clear . There is no pneumothorax or pleural effusion . There is no acute osseous abnormality .
    OUTPUT:
    
1 . Retrocardiac opacity most consistent with atelectasis , although pneumonia can not be excluded in the correct clinical setting . 2 . Cardiomegaly with a tortuous thoracic aorta .