Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is mild cardiomegaly . Low lung volumes exaggerate the hilar and mediastinal contours with crowding of the pulmonary vasculature . There may be a small left pleural effusion . There is no evidence of pneumothorax . Note is made of an opacity of the left lung base and medial right lung base which may represent atelectasis , although aspiration or pneumonia should be considered . The visualized osseous structures are unremarkable .
    OUTPUT:
    
Opacity at the left lung base and medial right lung base , may be secondary to atelectasis , however an acute infectious process can not be excluded . Clinical correlation is advised .