Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volume is low . There is no focal consolidation , pneumothorax or pleural effusion . Cardiac silhouette is exaggerated by low lung volumes . There is a mild diffuse interstitial abnormality which is similar to ___ .
    OUTPUT:
    
No radiographic evidence of pneumonia . Interstitial abnormality , could be chronic . Alternatively mild heart failure . Depending upon clinical circumstances , CT scanning may be appropriate for differentiation .