Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is top - normal , unchanged . Cardiomediastinal silhouette and hilar contours are unremarkable . Chronic scarring at the left lung base with a juxta phrenic peak is unchanged . Compared to the recent prior examination , there is mildly increased , subtle density at the bilateral left greater than right lung bases . No pleural effusion or pneumothorax .
    OUTPUT:
    
Mildly increased density at the lung bases compared to the recent prior examination which may represent pneumonia or aspiration . Dependent pulmonary edema is a less likely consideration .