Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is increased opacification of a medial left lung base which is likely due to atelectasis . There is no evidence of pneumonia or pulmonary edema . No large pleural effusion is evident . Cardiomediastinal and hilar contours are within normal limits . There are calcifications of the aortic knob .
    OUTPUT:
    
No overt signs of pneumonia or CHF