Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mild calcification of the aortic knob is present . The pulmonary vascularity is not engorged . Hilar contours are unremarkable . Relative lucency within the right lung base likely reflects bullous emphysematous changes . Linear opacities within the left lung base may reflect scarring or subsegmental atelectasis . The patient 's forearm obscures visualization of the left costophrenic angle . No large pleural effusion or pneumothorax is identified . There are no acute osseous abnormalities .
    OUTPUT:
    
Somewhat limited exam . Bullous emphysema . No acute cardiopulmonary process .