Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear stable , including mild to moderate cardiomegaly and a tortuous appearance to the aorta . Widening of upper mediastinal contours is apparently due to tortuosity of the great vessels and also unchanged . As better depicted on the lateral view there is an opacity in the posterior left lower lobe that is streaky and has increased but noting decreased lung volumes on the lateral view on this study . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
Posterior basilar opacity which appears more prominent although likely due to persistent atelectasis accentuated by low lung volumes . Follow - up radiographs could be considered , however , if clinical findings raise concern for developing pneumonia .