Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Low lung volumes bilaterally are unchanged since ___ . Markedly limited evaluation of lung bases with bilateral basilar heterogeneous opacities representing atelectasis or possible pneumonia . No new focal opacity . Cardiac silhouette is obscured by the elevated diaphragms . Lung apices are obscured by patient 's chin positioning limiting assessment for apical pneumothorax . Moderate degenerative disease of the left shoulder . Additional visualized bones are unremarkable .
    OUTPUT:
    
1 . Unchanged low lung volumes . 2 . Markedly limited evaluation of lung bases with bilateral basilar opacities is likely basilar atelectasis however may represent pneumonia in the appropriate clinical setting .