Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes remain low . There is mild cardiomegaly with left ventricular predominance . The mediastinal and hilar contours are unchanged , with mild calcification of the aortic knob . The pulmonary vascularity is not engorged . There has been slight interval improvement in aeration of the left lung base , with minimal residual streaky opacities in both lower lung bases likely reflecting atelectasis though aspiration or infection can not be completely excluded . No pleural effusion or pneumothorax is identified . There are multilevel degenerative changes of the thoracic spine along with a mild to moderate dextroscoliosis . Humeral prosthesis on the right is noted .
    OUTPUT:
    
Slight interval improvement in aeration of the left lung base with persistent residual patchy opacities at the lung bases which could reflect atelectasis . Infection or aspiration is not completely excluded .