Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Increased interstitial markings are seen bilaterally . Retrocardiac opacity is noted likely secondary to atelectasis . There is no effusion . Moderate cardiomegaly is unchanged . Tortuosity of the thoracic aorta which is moderately calcified is noted . Degenerative changes seen at the shoulders . No acute osseous abnormalities .
    OUTPUT:
    
Interstitial edema . Retrocardiac opacity , likely atelectasis noting that infection can not be entirely excluded .