Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There are low lung volumes , and crowding of normal bronchovascular structures . The cardiomediastinal silhouettes are grossly stable , possibly with mild cardiomegaly . Left lower lung opacity may represent atelectasis , however pneumonia or aspiration pneumonitis post be considered in the appropriate clinical setting . Right cardiophrenic angle opacity likely reflects crowding of normal bronchovascular structures . There is no pulmonary vascular congestion or pulmonary edema . There is no pneumothorax . Difficult to exclude a small left pleural effusion . No right pleural effusion .
    OUTPUT:
    
Low lung volumes . Left lung opacity may represent atelectasis versus pneumonia or aspiration pneumonitis in the appropriate clinical setting . Possible small left pleural effusion .