Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP portable view of the chest . There is a left lower lung opacity , decreased from prior study , with mild elevation of the left hemidiaphragm . This may represent pneumonia . The previously seen right basilar opacity has improved . No definite pleural effusion is identified . No pneumothorax . Low lung volumes .
    OUTPUT:
    
Residual bibasilar airspace opacities , most likely represent improving aspiration pneumonia .