Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Moderate cardiomegaly is re- demonstrated . The mediastinal contour is similar with atherosclerotic calcifications noted at the aortic knob . The pulmonary vasculature is not engorged . Retrocardiac opacity may reflect atelectasis though infection is not excluded , and findings are not substantially changed since the previous radiograph . Blunting of the left costophrenic sulcus also suggests a small left pleural effusion . No pneumothorax is identified . Marked degenerative changes are seen involving both shoulders .
    OUTPUT:
    
Retrocardiac opacity may reflect atelectasis or infection , not substantially changed in the interval . Trace left pleural effusion .