Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is moderately enlarged . Mild unfolding is noted along the thoracic aorta . Central pulmonary arteries are mildly prominent . The azygos vein also appears mildly enlarged , although there is no evidence for frank pulmonary edema . However , the lateral view suggests a patchy posterior retrocardiac opacity , most likely within the left lower lobe which is not specific as to etiology . There is no pleural effusion or pneumothorax . Mild degenerative changes are noted along the thoracic spine .
    OUTPUT:
    
Patchy posterior opacity which is nonspecific ; differential considerations include pneumonia in the appropriate clinical setting , although atelectasis may explain the finding . Cardiomegaly and slight vascular prominence without frank pulmonary edema .