Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: In the retrocardiac area , there is increased opacification , which may be due to a slight increase in size of the vessels or atelectasis , though in the proper clinical setting , a pneumonia can not be completely excluded . At the right apex , the known pulmonary nodule is difficult to visualize , though a vague opacity is present . The lungs are otherwise clear without new nodules . There is no pulmonary edema , pleural effusion , or pneumothorax . Minimal apical scarring is present . The cardiomediastinal silhouette is normal .
    OUTPUT:
    
1 . Increased retrocardiac opacification could be due to vessels or atelectasis , though in the proper clinical setting , an early pneumonia can not be completely excluded . 2 . Right apical pulmonary nodule is difficult to visualize , and better characterized on the recent PET - CT .