Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Patient is status post coronary artery bypass graft surgery . Lung volumes are low . Within the limitations of technique , the cardiac , mediastinal and hilar contours appear stable . There is no pleural effusion or pneumothorax . Widespread interstitial abnormality appears similar allowing for differences in technique . A large nodule in the left upper lobe is vaguely visible on radiography in the periphery of the left upper lung .
    OUTPUT:
    
Stable extensive background abnormalities , but no definite evidence of acute cardiopulmonary disease .