Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Two frontal chest radiographs were obtained with patient positioned upright . In comparison to two days ago , there is slight improvement in lower lung aeration . There is elevation of the right hemidiaphragm . No definite signs of pneumonia or CHF . There may be a tiny residual right pleural effusion . Cardiomediastinal silhouette is stable . Bony structures are intact . There is no free air below the right hemidiaphragm .
    OUTPUT:
    
Possible tiny right pleural effusion . Low lung volumes . No definite signs of pneumonia or CHF .